Model Engine Maker

Engines => Your Own Design => Topic started by: Vixen on October 25, 2017, 02:04:21 PM

Title: By Jupiter
Post by: Vixen on October 25, 2017, 02:04:21 PM
I have been given the unexpected opportunity to take over the build of this magnificent 1/3 scale replica of a Bristol Jupiter VIII FS radial engine. The engine is the work of Dan Robbin, but could easily have been the work of Faberge, it is a jewel, it is so exquisitely made.

Have a look at Dan's website, to see what I mean  www.danrobin.org/Jupiter/The_Project.html

At 1/3 scale the Jupiter is huge, with a displacement of approx 840cc. My first Mini had an engine of that capacity.

Here is the 840cc 1/3 scale Bristol Jupiter alongside one of my 360cc 1/4 scale Bristol Mercury radials.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060958.jpg)

                                       "Happiness, is a pair of big Bristols"



What a responsibility to take on, the completion of this engine

Mike
Title: Re: By Jupiter
Post by: Jo on October 25, 2017, 02:06:05 PM
 :cartwheel:  :cartwheel:   :whoohoo:  :cartwheel:  :cartwheel:  :pinkelephant:  ::)  :whoohoo:  :whoohoo:

Pleased it is safe and sound with you Mike, time to  :wine1:

Jo
Title: Re: By Jupiter
Post by: Ye-Ole Steam Dude on October 25, 2017, 02:30:06 PM
Great web site and amazing work.

Thomas
Title: Re: By Jupiter
Post by: Vixen on October 25, 2017, 02:50:22 PM
Some of the 'next page' links on   www.danrobin.org/Jupiter/The_Project.html  are not working. 

You should click the headings/topics on the top of the opening page to see everything

Mike
Title: Re: By Jupiter
Post by: b.lindsey on October 25, 2017, 03:23:13 PM
A beautiful engine Mike. How much is left to be done to finish it up??

Bill
Title: Re: By Jupiter
Post by: Vixen on October 25, 2017, 03:40:18 PM
Bill
All the ignition, twin magnetos, most of the fuel mixture plumbing and lots of little bits. The engine is only loosely assembled so will eventually need a full strip and final assembly. At my rate of progress, perhaps two years (or more) before it runs. Meantime, It will be displayed on behalf of Dan Robbin at our shows in UK.

I expect the Mercedes Benz W165 Grand Prix engine to take a back seat for a while, but I will continue to post 'progress' on the W165, until the posts are up to date with the actual build.
'
I have posted this in the Engines Showcase, but that says'no builds' . I don't think I should post in 'Your own Design' because it is Dan's work not mine. Any ideas where the build completion log should go?

Mike
Title: Re: By Jupiter
Post by: b.lindsey on October 25, 2017, 03:48:23 PM
Mike, i would assume perhaps "Engines from Plans" or "From Castings" if castings were involved.

Bill
Title: Re: By Jupiter
Post by: Jo on October 25, 2017, 04:25:55 PM
We will put it in "Your Own Design" and recognise that the Designer was actually Bristol and Danny/you are only reproducing a copy of it just a little smaller  ;)

And it would be good to put Danny's part of the build log in here as well  8)

Jo

Title: Re: By Jupiter
Post by: Jasonb on October 25, 2017, 08:09:31 PM
That should keep you out of mischief for a couple of weekends at least Mike ;) I do remember looking at Dan's site before but can't recall how or why I was there and good to see what can be done on just a Myford without a DRO in the form of the BR2.

Are you able to say whey he did is not able to see the project through to it's completeing?

J
Title: Re: By Jupiter
Post by: Vixen on October 25, 2017, 08:25:24 PM


Sorry, Jason  I am sure you will understand that I cannot reveal that on an open forum.

Dan's Bentley BR2 was awarded a Gold Medal at the 2002 MEX. Not bad for a self trained guy with only a Myford. The Bridgeport came later, so he could build the Jupiter. The Jupiter engine would have deserved a Diamond Medal, if there were such a thing.

Mike
Title: Re: By Jupiter
Post by: Jasonb on October 25, 2017, 08:38:30 PM
Thank's Mike, totally understand.
Title: Re: By Jupiter
Post by: Vixen on October 28, 2017, 01:07:28 PM
I would like to restart the build of the Bristol Jupiter by making the induction elbows and pipes located at the rear of each cylinder. The vertical pipe should be straightforward, it is a perfectly round thin wall tube. It is the tubular Vee shaped casting at the top which represents the challenge. There are three flanges and two 90 degree tubular bends. The bends transition from circular near the cylinder head to oval where they intersect.

(http://lister-engine.com/coppermine/albums/userpics/10013/cylinder_head_back.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/cylinder_head__top-rear.jpg)

These are photos of a preserved Jupiter engine located at the RR Heritage Trust Museum in Filton.

The inlet casting looks deceptively simple at first, but contains many potential problem areas and a total of nine are required.

I considered machining from solid on my CNC mill. I have used this technique many times as some of you will have seen on by Mercedes Benz GP engine build log. There will be problems with the overhang of the flanges and the internal curve, preventing access of the cutter. I guess only about 75% of the surface can be reached with the cutters. This will therefore require considerable hand work with the Dremel and hand files. It will also take a considerable amount of computer time and some cleaver geometry to generate the tool paths in 2.5 axes. Once 'good' tool paths have been proven, the complex machining and hand working would need to be repeated nine times.

How much easier it would be to hand carve a single master pattern and core and use a foundry to cast the nine manifolds. I can see there would be big problems with sand casting. The split line would need to bend through 90 degrees to follow the widest part of the two elbows, draft angles would be a problem as would core location to ensure a 2mm wall thickness. A certain amount of hand working would also be required but as much as with the all machined approach. I am not sure sand casting could give the casting the finesse I am looking for.

Lost Wax casting may be the answer. I know it will produce casting with the required accuracy, detail and finesse. I used this technique to produce similar inlet manifold casting for my 1/4 scale Bristol Mercury radial engine. I made silicon rubber molds off the master patterns into which to inject the wax, I used a soluble wax for the core. The soluble core was dissolved out in cold water and the finished wax sent of the the foundy for investment and casting. Alas, the company I used has closed down, as have so many others.

This is where I need to ask all the MEM European members for help. Do any of you know the name and contact details for a Lost Wax foundry which would be willing to work with and produce a small batch of castings for a hobbyist at an affordable price? I have found some industrial companies who are only interested in industrial quantities and who are not prepared to even talk to hobbyist.

Thanks for your help and understanding

Mike
Title: Re: By Jupiter
Post by: Jasonb on October 28, 2017, 01:18:00 PM
You could contact Adam at CRO fittings, he has a small stand at Guildford. If you give him your CAD drawing then he can get the part wax printed and cast, he mostly does his own stuff but I think may be willing to do custom jobs, I think Jo has talked to him more about this.

http://www.crofittings.co.uk/

There is also Abby Castings who could probably do it.

http://www.abbeycasting.co.uk/

There is also the chap who goes by the name Abbey on the forums who is Union Steam

http://www.unionsteammodels.co.uk/

Failing that G&M tools did have a nice little flame fast crucible furnace for sale ;)

J

PS what sort of sizes are these bits as that can sometimes limit who you can go to as it has to fit their flasks, maybe a couple of pics of the engine with something next to it would help give us an idea of the engines size.

PPS did you ever get a price back for the remaining 3D printed material on your list?
Title: Re: By Jupiter
Post by: Vixen on October 28, 2017, 01:40:30 PM
Hello Jason,

I guessed you would be the first to reply. Thanks for the advice. I will follow up on each of those leads.

I would prefer to produce the waxes myself. It should mean less outside work to pay for and I can be satisfied with the waxes before it is invested. Each inlet manifold measures a bit under 2.5" x 1.5" x 1.5".

I have a gas fired melting furnace but it is the burn out furnace which is the killer. Temperature stable at about 600*C for twelve hours.

Yes I have the full range of prices from Sculpteo and must find the time to update the information on the forum. Bottom line is: "if you want accuracy, you cannot afford it and if you want affordability, then you wont get accuracy". I will update the information soon..... promise

Thanks again

Mike
Title: Re: By Jupiter
Post by: Vixen on October 28, 2017, 02:04:08 PM
Here is a photo to give you all an idea of the size and weight of the 1/3 scale Bristol Jupiter.

Mike

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060964.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060965.jpg)

Title: Re: By Jupiter
Post by: Jo on October 28, 2017, 02:29:43 PM
I wondered how long it was going to take to recover from the "welcome to the family Jupiter" celebrations  :wine1: :Lol:



Adam has his lost waxes done in Aussie as it is cheaper. He sends them the drawing file, they do a high quality 'wax' print and then they cast them before posting them round the globe. The quality of the finished pieces speaks for themselves  ::) Yes he will get items done for customers but he normally does bronze, you will have to ask about ali.


My supplier has the ability to do diecast goodies in his garden (he just needs the motivation). Have you thought of doing them as Diecast? And you know Mike Coles does Ali castings, he may have other suggestions. I wonder if you could do ali castings similar to how they make chocolate easter eggs  :noidea:


If only you had asked yesterday  :facepalm: .... the SMEE are had their rummage sale today and someone there may have had other suggestions.

Tangler has a nice stable furnace which might be suitable for the burn out  ;)


Is the original Ali or should it be some sort of Nickel/steel?

Jo

P.S. Don't forget to take it to the Bristol show next year so you can use it to make friends with the works boys you never know what they may be able to come up with.

Title: Re: By Jupiter
Post by: Ye-Ole Steam Dude on October 28, 2017, 03:08:16 PM
WOW and outstanding. Hard to believe the effort that went into that engine. Just beautiful. Being an old pilot and spending a lot of time out at the "grass airport", nothing like hearing a radial engine running. One of the local crop dusters or a friend of mine that had a twin Beachcraft D-18.

Thanks for sharing,
Thomas
Title: Re: By Jupiter
Post by: Jasonb on October 28, 2017, 05:07:08 PM
As you are likely to put a black finish on the parts does the material matter?

Jo Does Adam have the casting done here or is the whole lot done down under?

Regarding the first photo, I think you will find it more common to strap the engine to your back when Motor paragliding ;)
Title: Re: By Jupiter
Post by: Vixen on October 28, 2017, 05:33:53 PM
I would always prefer to see well finished, naked material on a model replica, not something hidden by coats of paint and filler. My personal view.

Sculpteo and some of the  3D print houses also offer lost wax casting in various materials. Sounds like the sort of service Adam uses. Sculpteo 3D print the wax, invest it then cast it , all done in house. They were very cagey about shrinkage allowances and would not give any guidance as to what to expect and how to compensate. Said it would end up with 3 to 4 % error, Plus or Minus and I needed to try one and see. They are mostly used for making jewelry rather than precision engine parts. If I needed precision, they advised the mega expensive Laser sintered metal powder route.

Think you are right about paraglider motors

Mike
Title: Re: By Jupiter
Post by: Jasonb on October 31, 2017, 07:57:46 AM
One more lead that Neil on ME suggested, looks like they will cast from your own waxes and do Aluminium

http://justcastings.co.uk/what-we-do/casting/
Title: Re: By Jupiter
Post by: Vixen on October 31, 2017, 11:54:44 AM
Thanks for that link Jason. Justcastings (Jc) look ideal and I will get in touch with them today.

Interestingly, Jc are in Hatton Gardens, the jewelry making district of London, I have also made contact with another jewelry maker in the Brimingham jewelry district. Both firms are happy with casting aluminium and working small quantities.

Only CRO have responded from your original list. They can offer to print a wax from a 3D model. The wax will be printed in New Zealand and shipped back to UK for the foundry work. They can only offer brass/bronze in NZ. Sounds very much like the Sculpteo situation to me.

I will keep you all updated, as finding a good foundry for lost wax casting may be of interest to other MEM members

Title: Re: By Jupiter
Post by: Vixen on December 03, 2017, 01:06:34 PM
I have found from Jason's list, a lost wax foundry who are affordable and willing to work from master patterns rather than printing a 3D model.

I have made a start on the master patterns. There are two required. The first is the core pattern, the pattern will be encased in silicon rubber mold, so that the soluble wax core can be made. The second pattern defines the outside shape and is similarly encased in silicon rubber to form the wax mold. The soluble wax core core is placed inside the outer silicon mold, the wax is injected and the soluble wax dissolved out with water. The wax shell is then invested in a special plaster, given 12 hours in the burnout furnace before the aluminium is pored. A vacuum is applied during the pore to ensure a total fill of the cavity.

These days, I make all my patterns out of acrylic sheet, also known as Pespex or Plexiglass. The pattern is built up from a number of 3mm thick layers of acrylic sheet which are milled to shape on my Emco F1. The layers are solvent welded together using Tensol No 12 cement. The rough pattern halves are then filed to shape and sanded smooth with Wet-n Dry paper.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060966.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060967.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060968.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060970.jpg)

I made up a simple jig to bevel the joint faces between the two elbows. The pattern parts were roughly filed to the bevel angle and finished by pulling a strip of Wet-n Dry between the jig and the pattern.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060971.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060973.jpg)

When both halves have been beveled to the correct angle, they can be cemented permanently together using the same jig.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060974.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060976.jpg)

More on the Inlet Manifold pattern making to follow in the next installment

Mike

Title: Re: By Jupiter
Post by: steamer on December 03, 2017, 01:39:35 PM
Thanks for sharing that!    Nice work!

Dave
Title: Re: By Jupiter
Post by: Jasonb on December 03, 2017, 03:53:28 PM
Good to hear one of those links could sort you out Mike, out of interest which one was it?

I'd not heard of the soluble wax before but sounds the ideal way to core a wax and be able to get the core out without damage to the wax or having to do it as two halves. Just hope those lugs on the manifold come out of the silicon OK.

J
Title: Re: By Jupiter
Post by: Vixen on December 03, 2017, 04:15:00 PM
Hi Jason

Out of the list of potential lost wax foundries you provided, I feel most comfortable with, having talked at length with Richard at Abbey Castings. http://www.abbeycasting.co.uk/

Just Castings are in reserve, just in case. http://justcastings.co.uk/what-we-do/casting/

I have used soluble wax on several occasions to core lost wax castings. A typical soluble wax is available on e-bay at https://www.ebay.co.uk/itm/Water-Soluble-Wax-used-in-lost-wax-casting-jewellery-jewellers-silversmithing/221919526624?hash=item33ab6f3ee0:g:ih0AAOSwYHxWJ6~3

It is important to use wax which is soluble in cold tap water and not to try and speed things up by warming the water. The investment wax softens at around 70*C to 80*C and is runny liquid by 100*C. Even the warmth of your fingers can mark the investment wax if you handle it for too long. Always a good idea to cool it in tap water from time to time.

I have decided not to attempt to add the lugs for the spark leads to the casting. They are be screwed in place afterwards.

Mike
Title: Re: By Jupiter
Post by: Vixen on December 08, 2017, 07:47:11 PM
The patterns for the soluble wax core and main wax have been completed and given their first coat of primer. It's amazing how the small blemishes show up, but nothing that cannot be fixed with some knifing filler. The base and cylinder flanges were machined in acrylic and cemented in place.

Next things to be made will be the silicon rubber molds into which the soluble wax is injected to create the core The wax core is then positioned within the main mold and the hard red wax injected, it surrounds the soluble wax core. The soluble wax is dissolved out in cold water leaving the thin shell of the inlet manifold which is then sent to the foundry for investment and casting.

Mike

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060985.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060984.jpg)
Title: Re: By Jupiter
Post by: Jasonb on December 08, 2017, 07:51:44 PM
Looking good :)
Title: Re: By Jupiter
Post by: Vixen on December 12, 2017, 05:01:09 PM
The next task was to mix and pour the silicon resin into the mold boxes.  It is a 24 hour cure and one always worries that something will go wrong, that it will not set-off, and you have to sort out a very expensive sticky mess. The first photo shows some kitchen chemistry, I mixed 600ml of silicon resin plus 10% catalyst for the two molds. The next two photos show the two fully cured molds after they were cut open to remove the pattern pieces. The rough jagged cut is intentional as it aligns the two halves better than a smooth cut. There are also three plastic dowels to align each mold. The final photo shows the core pattern sitting inside the main mold, there is about 2mm clearance (wall thickness) all around the core. I have some soluble wax on order to make the nine cores. It is expensive, so I waited to see if the molds were good before I ordered the soluble wax. Now I am thinking about the big manifold between the carburetor and the induction spiral.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060986.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060989.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060992.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060993.jpg)


Title: Re: By Jupiter
Post by: mikecole7 on December 12, 2017, 07:11:24 PM
Well done Mike your work is brilliant, It will great to see it at the Bristol show

    Mike

Title: Re: By Jupiter
Post by: Jasonb on December 12, 2017, 07:32:42 PM
They came out quite nicely. Do you use any form of vacuum degassing? I did notice some bubbles in the moulds. I know from when I used to paint model figures which were mainly cast in PU resin using silicon moulds that vac degassing was always advised both when making the mould and also casting the PU figures.
Title: Re: By Jupiter
Post by: Vixen on December 12, 2017, 07:45:04 PM
Thanks Mike,

When I saw the valve gear on top of your Scorpion, I was envious. So when the 1/3 scale Jupiter became available, I could not resist.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1060995.jpg)

Here is the 3% oversize inlet manifold pattern against the Jupiter cylinder head so it does not quite fit.  Lots of interesting valve gear on the Jupiter

Looking forward to the Bristol show in August, also hope they can do something at Guildford but on a smaller scale than before

Mike

Title: Re: By Jupiter
Post by: Vixen on December 12, 2017, 07:50:05 PM
Hello Jason,

The silicon resin is heavy and quite runny. It is a 24 hour cure so the air bubbles, which are inevitable when you stir the mix, have time to rise to the surface. The molded surface is clean but there are some bubbles under the top surface of the mold box. If I had a bell jar and a vacuum pump, I would use them, but unfortunately.........

Mike
Title: Re: By Jupiter
Post by: Vixen on January 18, 2018, 12:27:47 PM
Before christmas I completed the two silicone rubber moulds for the core and main waxes. The time has come to get serious and create the wax models before sending them to the foundry for the hot work.


(http://lister-engine.com/coppermine/albums/userpics/10013/P1070002.JPG)

This first photo shows my 'kitchen chemistry' approach to melting and injecting the wax into the moulds. My wax injection pump is a modified cookie maker which has quick connect bayonet end caps at each end. I made up a new aluminium piston with an O-seal piston ring and a conical nozzle. The wax inside the cylinder is heated in a Bain Marie style water heater made from an old coffee tin. This ensures the wax temperature remains constant and never exceeds 100*C.


(http://lister-engine.com/coppermine/albums/userpics/10013/P1070001.JPG)

Here you can see the 9 soluble wax cores and the silicone core mould


(http://lister-engine.com/coppermine/albums/userpics/10013/P1070005.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070006.JPG)

Here is the core wax positioned inside the main silicone mould after the red (non-soluble) wax has been injected and allowed to cool.


(http://lister-engine.com/coppermine/albums/userpics/10013/P1070010.JPG)

The waxes are placed in cold water overnight to dissolve out the soluble wax core. The wax model is now ready to send to the foundry for the hot work. At the foundry they add wax runners and risers to my waxes before placing them in a casting flask filled with special investment plaster. The wax in burned out of the casting flask in an oven at red heat before being transferred to a vacuum caster where the molten aluminium is drawn into the flask.


(http://lister-engine.com/coppermine/albums/userpics/10013/P1070033.JPG)

I sent two sample waxes to 'Just Castings Ltd' a specialist foundry located in the famous Hatton Garden Jewelry district in London. So I now proudly say that I have two lost wax inlet manifolds cast by a jeweler by Royal Appointment to Her Majesty. They kindly added a few candy sweeteners with the order, to soften the blow of the cost.  The cost of an individual casting is not that bad, but nine castings to which must be added the dreaded 20% VAT tax, is a different story.


(http://lister-engine.com/coppermine/albums/userpics/10013/P1070030.JPG)

Here we can see the different stages. The master patterns for the manifold and the core, the finished wax model and the final investment cast item in aluminium. Sometimes there is no substitute for an expensive bespoke casting, when the internal shape cannot be machined out of the solid.

Title: Re: By Jupiter
Post by: Ramon on January 18, 2018, 01:03:33 PM
Expensive they might have been Mike but what a result from all the input you have put in to get the finished item. Way beyond my best intentions, that's model engineering at it's best - well done indeed :praise2:

Tug


Title: Re: By Jupiter
Post by: b.lindsey on January 18, 2018, 01:15:02 PM
Most impressive Mike (excellent pictures also) and the results speak for themselves. Somehow I'm thinking the two candies didn't soften the cost a lot but it was a nice gesture none the less.

Bill
Title: Re: By Jupiter
Post by: Jasonb on January 18, 2018, 01:25:23 PM
They look to have turned out really well Mike, good to know the company were able to do them.

Couple of questions:

1. Were you able to indicate where the runners should be attached? If so I assume they went onto one of the mating surfaces that is going to be lightly machined.

2. What is the dimensional accuracy like as that was a big issue with the printed options?

Lastly, don't let Jo get hold of your silicon and wax supplies otherwise her castings may start to multiply ;)

J
Title: Re: By Jupiter
Post by: Vixen on January 18, 2018, 01:46:40 PM
Hello Jason

'Just Castings' were one of the foundries on your list of suggested suppliers. They were the only people to show any 'real' interest in the job. Most of the others did not bother to respond to e-mail questions. They are a professional outfit, they cast various metals (mostly precious metal) every day of the week and are incredibly well equipped to do the work. They are not a 'hobby' foundry.

I did indicate where I thought the runners and risers should go. I used the end flanges for the wax injection, you can see the stub ends on the red wax model. JC did it differently, they attached the runner to the outer curved surface, in full view. It turns out that they knew best (that's always a good sign) and their position for the runners was easy to cut off and file smooth. I was having some problems with the wax not completely filling the cylinder flange bosses. JC showed me how to build up the wax using a knife blade heated in a candle flame. The additional wax can be carved to shape once it has cooled.

I made the Master patterns 3% oversize to compensate for the various shrinkages. The finished casting ended up about 1% under size. Not a problem as I will drill and counter drill the flanges using a drilling jig plate, so the bolt holes will line up perfectly.

Jo or anyone else are more than welcome to make use of the silicone moulds to make their own waxes.

Mike
Title: Re: By Jupiter
Post by: mikecole7 on January 18, 2018, 01:48:25 PM

       Brilliant as usual Mike, I'm still having trouble working out the last casting stage.
       Really great work.

      Mike
Title: Re: By Jupiter
Post by: Jo on January 18, 2018, 02:01:53 PM
Looks very nice Mike  8)


       Brilliant as usual Mike, I'm still having trouble working out the last casting stage.
 

Maybe we should get him to bring it all along to Bristol so he can show all the members of ICEBG and we can all fondle his castings ;D

Jo

P.S. Still reading the Bentley book... might have to get Eric to pull his finger out and cast the required exhausts for that just in case I find the need  :embarassed:
Title: Re: By Jupiter
Post by: Vixen on January 18, 2018, 02:19:55 PM
Hi Jo,

Good idea, I will bring the master patterns, moulds and some waxes to Bristol. I did similar (smaller) inlet manifolds for the 1/4 scale Mercury. I will bring them as well and you can get to fondle all those castings as well.

I promise not to tell Uncle Eric how much the Jupiter castings cost, otherwise he may get BIG ideas for casting the Bentley manifolds. I think he may have done the castings for Dan's Gold Medal winning Bentley from the same set of dies.

Keep safe

Mike
Title: Re: By Jupiter
Post by: Dave Otto on January 19, 2018, 12:19:34 AM
Hi Mike

Thanks for the update, the manifolds turned out very nice. It is nice to know that this can be done with out an expensive wax pot.
Do you put the silicone mold in any kind of support structure when you inject the wax into it? It seems that just holding in your hand that the wax may want to squirt out of the part line?
Also I was wondering if you have any issues with air bubbles in the wax?

Dave
Title: Re: By Jupiter
Post by: Vixen on January 19, 2018, 09:23:23 AM
Hello Dave,

Half the fun is making do with what is available. I would love to own an expensive wax pot and a vacuum bell jar but I cannot justify the expense for so few castings.

The silicone mould is quite flexible so I support it in a four sided box, actually four separate plates and rubber bands, while I inject the wax. The secret seems to be to get the wax to a high temperature which makes it thin and runny, then there is less tendency to hydraulic the two parts of the mould appart.

When you make a batch of waxes, it gets into a one hour cycle. Inject wax, allow to solidify, open mould, clean up, reassemble mould and inject again. I found it better to keep the molten wax at temperature in the Bain Marie all the time. I can remove the handle and stand the cylinder full of wax, vertically in the simmering water pot. This has the added advantage of keeping the metal nozzle at temperature, so The wax does not cool and solidify in the nozzle during injection.

For the test samples I used some old, several times, recycled wax. It was contaminated and full of minute air bubbles. The resulting casting had a rougher surface which needed extra work to clean up and smooth off. Now that I know the process works, I will use virgin wax for the 'production' run.

I did have a problem with the wax not always completely filling the flange boss cavities. JC showed me how to build up the wax using a knife blade heated with a candle flame. The excess wax is easily carved to shape once it cools. It is always better to have too much metal in the casting than too little.

Here are some photos of one of the inlet manifolds roughly in position behind the cylinder head. The black delivery tube is some undersize plastic pipe from the scrap box. I have found some 22mm diameter, thin wall aluminium tube to make the real delivery pipes. The Bristol radial engines of this era were designed with style.

Mike

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070036.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070034.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070035.JPG)

Title: Re: By Jupiter
Post by: Dave Otto on January 20, 2018, 12:22:42 AM
Hi Mike

Thanks for the additional information, do you think it would be possible to preheat the silicone mold to help the incomplete filling problem? It seems that you could put the mold in an oven and bring the temp up quite a bit above ambient to keep the wax from freezing so quickly?

I'm not sure what I would make but I would sure like to give this a try sometime.

Dave
Title: Re: By Jupiter
Post by: Jasonb on January 20, 2018, 07:21:55 AM
Possibly air getting trapped in the bosses, a small vent would allow that out and the wax that enters the vent can just be trimmed off. A simple "Vee" cut with a scalple would form the vent in one of the mould faces.
Title: Re: By Jupiter
Post by: Vixen on January 20, 2018, 12:10:45 PM
Hi Dave and Jason

Thanks for your helpful suggestions, it is gratifying to know someone out there is interested.

Jason, the problematic flange boss is in the lower half of the mould, surrounded by the greatest mass of silicone. The boss in the top half where air would collect appears unaffected. The wax casting has all the characteristics of a chilled pour rather than bubble entrapment. I believe Dave is near the mark with his suggestion of pre-heating the silicone mould.

There are several grades of wax, I am using the 'red' wax, intended for injection moulding. The wax does not have a distinct melting or freezing point. At room temperature 20*C, it is a rigid solid. At 40 to 50*C it softens like putty. At 60 to 70* it flows like a paste. Above 80* C it is a slush and near 100*C it is a free flowing liquid. I have found that it is also a poor conductor of heat, so takes forever for the solids to melt into the surrounding liquid wax. I found it necessary to maintain the wax, all day, in the molten condition and to avoid adding fresh wax to the melt.

Producing the batch of nine waxes was an epic in itself. It required a complete take over of the good ladies kitchen and all it's facilities. Wax melting and conditioning started soon after breakfast. The first wax was produced just after lunch and the one hour, inject, cool, clean, rebuild mould, cycle began. The first moulds were injected with the silicon moulds at room temperature. The first waxes were the best quality.

Operations had to stop when the time came for the evening meal to be prepared. When the hostilities were over, I was able to continue, I wanted to complete the whole batch of nine in one day to avoid consuming a following day as well. I tried to reduce the one hour cycle time by cooling the injected wax mould in the fridge. It did take about 15 minutes off the cycle time. It was past midnight when the last wax was completed. It was only the next day when I discovered that the last few waxes were cast 'short'. So I tend to agree with Dave, a warmer silicone mould should prevent premature wax cooling and shrinkage. Will try harder next time and only attempt a smaller batch.

Dave, if there is no other alternative, then try lost wax. It is an exercise in frustration, time and expense. It's like opening your wallet and asking the man to take out whatever he wants. The patterns were made from materials in the shop, but took a long time to make. The two silicone moulds consumed £30 of material. The nine soluble wax cores consumed £25 of wax. The red injection wax was a further £20. The cost of each individual aluminium casting was £31 plus the dreaded 20% VAT tax. Not an undertaking for the faint hearted. If there is an alternative, use it.

Cheers

Mike
Title: Re: By Jupiter
Post by: Ian S C on January 20, 2018, 01:05:04 PM
Probably not relevent to the subject here, but I have read of manifolds being made by electro depositing copper on a wax form, I think the flanges were silver soldered on after the elbow was formed. Your method seems a much better (more expensive) method, the engine you have chosen  sets a high standard to follow.
Ian S C
Title: Re: By Jupiter
Post by: Jim Nic on January 20, 2018, 01:11:26 PM
", it is gratifying to know someone out there is interested."
It's not that I'm not interested, it's that I am agog at the the skill shown and the lengths gone to (not to mention the apparent expense) to produce just one part of a model. 
I have no knowledge of the process so have nothing to contribute except admiration, so please keep up the story.
Jim
Title: Re: By Jupiter
Post by: kvom on January 20, 2018, 01:20:37 PM
Very impressive engine and a daunting prospect to take over.  Hopefully these manifolds are the hardest part.
Title: Re: By Jupiter
Post by: Vixen on January 20, 2018, 02:41:31 PM
Ian  Electrodeposited copper over wax was used to form the inlet manifolds and water jackets of several engines during the 'Great War'. To me it was yet another unknow technique for which I am not equipped. I had done some small scale lost wax castings before and had some basic equipment. Better the devil etc.

Incidentally, we are planning a visit to NZ next Christmas to see our son. He spent last year helping rebuild Ch.Ch after the big shake. We would love to meet up with you and other members while we are down that way.

Jim  I do not mind going to great lengths to produce a fine replica engine but would have prefered less expense.

Kvom, It would be nice to think these manifolds were the hardest part but I fear the water heated manifold between the engine and the carburetor and also the induction spirol will present their own challenges. Was it President Kennedy who said, "We don't choose do it because it is easy etc."

Same could be said for your Colibri, nice work.

Cheers

Mike
Title: Re: By Jupiter
Post by: kvom on January 20, 2018, 06:08:31 PM
Thanks, but the Colibri presents no real difficulties beyond the size of the parts as far as constructing it goes.  The real question is how well it will run with metal parts vs. wood.  Are you planning to finish your small scale plastic version?  I considered reducing the size myself but wasn't sure I could find the proper shoulder heim joints.
Title: Re: By Jupiter
Post by: Fugell on January 24, 2018, 09:17:09 AM
Best of luck and keep us posted Mike. That's a marvelous engine.
Title: Re: By Jupiter
Post by: Vixen on January 24, 2018, 12:28:02 PM
I took advantage of the milder weather and ventured out into the workshop to fabricate the parts for an engine running / display / build stand. I was always fearful that the Jupiter could and would eventually topple over in the wooden stand. Besides it could not be doing the valve gear for the bottom two cylinders any good with the weight of the full engine bearing on the valve gear,  The steel tubes were recycled from an old high stool, the bends were neat and in just the right place for this engine stand. I have provision for adding extra side bars, if required, to hold the engine down while it is running. I disposed of our welding gear some time ago (I never could achieve a neat cosmetic weld), so called in our friendly local mobile welder to do the job. He turned up in a white van, with a fully equipped welding workshop in the back. MIG, TIG, Plasma, compressor, grinders, argon, Co2,  mixed gas cylinders: the full works. It took him half an hour on the drive to do the welding and a further two hours to talk about engines.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070037.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070041.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070038.jpg)

You can also see the Flight Case I built to store and transport the Jupiter. As you can imagine, I was not able to find a case of the right size, so I bought a second-hand guitar Flight Case from some failed rock and roll star, off E-bay. It was all the wrong shape but provided all the materials and fittings I would need. I dismantled it completely, cut the panels to my bespoke size and reassembled it. All I am awaiting is the four new fold flat carrying handles, they are coming on the slow boat from China.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070024.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070025.jpg)

Mike
Title: Re: By Jupiter
Post by: Roger B on January 24, 2018, 01:42:08 PM
Ian  Electrodeposited copper over wax was used to form the inlet manifolds and water jackets of several engines during the 'Great War'. To me it was yet another unknow technique for which I am not equipped. I had done some small scale lost wax castings before and had some basic equipment. Better the devil etc.

I'm also following along and learning  :)  :wine1:

One of my previous employers used to make high precision waveguides for linear accelerators by machining the 'space' out of aluminium, electro depositing the copper and then melting out the aluminium.
Title: Re: By Jupiter
Post by: Jo on January 24, 2018, 01:51:18 PM
Looks like better welding than I can do  :)

Jo
Title: Re: By Jupiter
Post by: Admiral_dk on January 24, 2018, 09:05:53 PM
Great stand for a Fantastic Engine  :praise2:

Nice flight case too - but here I can't help myself, from my line of work nowadays, as I'm in the music business - the case should be filled with foam, to make sure that it doesn't rattle inside the box (you probably thought of this already).
I can think of two ways to do this - either the "easy way" as in a former thread here (or was it HMEM  :noidea: ) - wrap the engine in plastic film, and "cast" the foam around it, or get a full block of the stuff and "cut the engine out of it" and glue the rest into the case. The thread was about making drawers for tools - I think it was Achim - but I might remember this wrong ....

The last is apparently also easy with the right tools. The father of my Boss makes high quality flight cases and he spend a few thousand Pounds on the tool to do so .....

Nice to see you back here with more projects Tug  :popcorn:

Best wishes

Per
Title: Re: By Jupiter
Post by: crueby on January 24, 2018, 09:14:22 PM
Great stand for a Fantastic Engine  :praise2:

Nice flight case too - but here I can't help myself, from my line of work nowadays, as I'm in the music business - the case should be filled with foam, to make sure that it doesn't rattle inside the box (you probably thought of this already).
I can think of two ways to do this - either the "easy way" as in a former thread here (or was it HMEM  :noidea: ) - wrap the engine in plastic film, and "cast" the foam around it, or get a full block of the stuff and "cut the engine out of it" and glue the rest into the case. The thread was about making drawers for tools - I think it was Achim - but I might remember this wrong ....

The last is apparently also easy with the right tools. The father of my Boss makes high quality flight cases and he spend a few thousand Pounds on the tool to do so .....

Nice to see you back here with more projects Tug  :popcorn:

Best wishes

Per
A few weeks ago someone showed me that thread, its for casting fitted drawer liners for tools and such. Here is a link to it on MadModder:
http://madmodder.net/index.php?topic=4770.0
Title: Re: By Jupiter
Post by: Vixen on January 24, 2018, 10:05:12 PM
Hi Per and Chris

I was proposing to secure the engine stand to the lower half of the Flight Case with clamps. I did not know how I was going to constrain the engine within the top half of the case to stop it shaking about. Now I know how to do it.

Thanks to you both.

Since the photos were taken I have fitted 8 ball corners to the Flight Case.

Mike
Title: Re: By Jupiter
Post by: Vixen on February 09, 2018, 01:43:46 PM
Another four inlet manifolds have arrived from my Hatton Gardens jewellers. If anything, these four are nicer than the first pair with almost no fettling required, except for the obvious removal of the casting feeder. The foundry cleverly positioned the feeder to make it easy to cut off and file smooth. I will order the final batch of three inlet manifold castings out of next months allowance. Just Castings Ltd do the lost wax castings very quickly and efficiently. One week from posting the waxes to delivery of the castings by recorded delivery. And they send candies every time.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070046.jpg)


I have made this drilling fixture to hold the castings accurately, while I drill the bolt holes in the flange. I will wait untill all nine castings are available and do them as one big batch

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070047.jpg)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070048.jpg)


While all the inlet manifold casting work has been going on, I have been busy making 18 exhaust stubs for the opposite side of the cylinder heads. The flange was milled from mild steel plate, the tubular part from 16mm diameter steel tube. I made a swaging tool, right of photo,  to expand the tube into a recess milled in the rear face of the flange. Not looking forward to making all those 8BA studs. 18 x 4 = lots of tedium.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070045.jpg)

Mike
Title: Re: By Jupiter
Post by: Jo on February 09, 2018, 01:47:55 PM
I can tell you have been bitten by the Jupiter bug Mike  ;)

And they send candies every time.

That is to help you get over the shock of the cost  ::)

Jo
Title: Re: By Jupiter
Post by: Jasonb on February 09, 2018, 01:57:04 PM
. And they send candies every time.
That explains why you are order in them in several batches.

Exhaust stubs look good too.

J
Title: Re: By Jupiter
Post by: Vixen on February 09, 2018, 02:02:31 PM
I can tell you have been bitten by the Jupiter bug Mike  ;)
Jo

Radial engines have always been my first love. And you know I have a 'thing' about big Bristols >:D >:D

Mike
Title: Re: By Jupiter
Post by: Myrickman on February 13, 2018, 10:33:58 PM
Wow Mike, I certainly learned a bunch about investment casting from your posts. The part about using the water soluble wax  was very educational and is filed away for future use.  With hardware like those radials, perfection is the only option; you certainly did them proud. Bravo. Paul
Btw, if you evacuate the silicone resin to say 27" vacuum until it froths and collapses, you can get 100% pore free mold castings. I'd venture to say on the wax casting that evacuating it in the filled state  would also help those pesky air pockets.
Title: Re: By Jupiter
Post by: Chipswitheverything on February 14, 2018, 08:54:30 AM
Just been enjoying the re-reading of this post all the way through, Mike.  The work described, and the components that have resulted, are absolutely remarkable, almost beyond what most of us conceive of as model engineering.
 Probably unlikely ever to be tackled by many, but your very clear explanations and detailed photos are fascinating, and give more than a glimpse as to where model engineering can be taken, beyond the machining type of processes that are generally familiar to us.     Dave
Title: Re: By Jupiter
Post by: Vixen on February 14, 2018, 10:18:58 AM
Thanks guys.

I am pleased to have you following along on this journey. Lost wax casting goes way back in history to Egyptian and Babylonian days and perhaps beyond.

Lost wax casting will never be the first choice in a machine shop, but there are some shapes which are near impossible to machine from a solid billet or make from a simple sand casting. Sometimes lost wax castings are the only option. I have tried 'to show every step of the journey, from carving the basic pattern, through the silicon mould making and wax injection processes. After that comes the 'hot work' and I found it best to give that to the professionals. Despite the help from the foundry, I still feel I have made the inlet manifolds all by myself.

I have enjoyed creating these castings, making do with what's available and then recording the process for other MEM members to follow and perhaps, one day, to try for themselves. That's the great thing about MEM, the openness with which members pass on experience and lessons learned (often the hard way). I feel it is important to share this knowledge and  experience, the successes and the failures.

I am sure the quality of the moulds and wax injection would improve if I had a vacuum degassing chamber and pump. They are expensive items and I cannot justify the cost for a limited number of lost wax castings. I have to live with the problem of air bubbles.

Mike

Title: Re: By Jupiter
Post by: Vixen on February 23, 2018, 12:58:23 PM
I am still awaiting the final three inlet manifold casting from the 'Just Castings' foundry in Hatton Gardens London

In the mean time, I made a start on the pattern making for the induction manifold which sits between the triple barrel up draft carburetor and the rear of the engine. It is in effect three separate 90* bends all in one casting. There is an added complication as there is a hot air heating pipe running from side to side. This was intended to heat the incoming mixture and prevent iceing at altitude. Here is a photo from the manual. I think this one will be a challenge.

(http://lister-engine.com/coppermine/albums/userpics/10013/CAP1.jpg)


I started with the three core patterns for the three independent internal passages. You can see how I made them from the photos. I started by milling out and cementing together a pile of 5mm perspex laminates. The laminates and the cylindrical core print extensions were assembled in a simple jig to ensure correct alignment. This jig will also be used again to make the outer pattern.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070050.JPG)


They were then roughly carved and filed to shape in the jig, at this stage reminded my of a handful of conkers (chestnuts).

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070053.JPG)


I then carefully smoothed them with 'wet n dry' paper and applied a coat of primer paint. Suddenly, they started to look obscene, like a row of old grey ladies doing the Can Can.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070058.JPG)
(http://lister-engine.com/coppermine/albums/userpics/10013/P1070057.JPG)

Mike
Title: Re: By Jupiter
Post by: fumopuc on February 23, 2018, 07:19:45 PM
Hi Mike, always a pleasure to follow your projects.
Title: Re: By Jupiter
Post by: zeeprogrammer on February 23, 2018, 11:52:08 PM
All of this is way beyond me but I sure enjoy following along and learning.  :ThumbsUp:
Title: Re: By Jupiter
Post by: crueby on February 24, 2018, 03:29:03 AM
Wow, that is some impressive sculpting!


 :popcorn: :popcorn:
Title: Re: By Jupiter
Post by: Vixen on February 24, 2018, 11:58:37 AM
Hi there,

Thanks for following along and posting your comments. Always welcome.

The Bristol Jupiter is full of challenges, which constantly push the envelope into those distant corners not frequently visited by model engine makers. I am trying to record my pattern making and lost wax activities in the hope that one day one or two of you (Zee?) will say "I need to do some of that and I remember Mike showed how it could be done".

These days,  perspex (acrylic) is my prefered pattern making material. It can be used for sand casting or lost wax patterns. Acrylic sheet is readily available to buy on the net. It cuts easily and machines beautifully. Laminates can be cemented together rigidly with Tensol no 12 cement. The laminated blocks are very easy to carve with rotary files and rifler files; provided they are SHARP and you keep the speed down. I have discovered the best way to carve the acrylic block is to use light pressure and a series of long sweeps, with the Dremel at it's lowest speed setting. This removes the material in a controlled manner with little tendency to dig in or groove. These are my weapons of choice.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070067.JPG)

Sharp files, both rotary or hand, are most important. Files which have tasted steel of have been allowed to rub against each other quickly become useless, they rub and melt the plastic instead of producing fine dust. The same is true for any files in the workshop especially those used to work brass and bronze. However, I am sure must of us, myself included, still throw most our files into a draw rather than store them properly. When I buy new files, which I do regularly, I always avoid those sold loose in a box, I look for files individually wrapped in brown paper.

Mike
Title: Re: By Jupiter
Post by: petertha on February 25, 2018, 12:30:07 AM
At my rate of progress, perhaps two years (or more) before it runs. Meantime, It will be displayed on behalf of Dan Robbin at our shows in UK.
I expect the Mercedes Benz W165 Grand Prix engine to take a back seat for a while, but I will continue to post 'progress' on the W165, until the posts are up to date with the actual build. Mike

What an incredible piece of work! I'm thrilled to see your posts & work on this new project, but at the same time will miss the W165 updates. I guess there is only so much Mike to go around :)

Maybe I missed them, but do you have a build post/series on your own radial?
Title: Re: By Jupiter
Post by: Dave Otto on February 25, 2018, 01:02:52 AM
Hey Mike, I'm still here, enjoying following along with your lost wax pattern making part of this project.

Dave
Title: Re: By Jupiter
Post by: Vixen on February 28, 2018, 04:25:40 PM
Both JasonB and Myrickman have commented about the presence of air bubbles in the silicon rubber moulds and possibly also in the wax itself. So far I have been lucky and the bubbles have not yet caused a problem, but ithey could, one day.

I looked at commercial degassing systems; way too expensive at 200 to 300 £, $, Euro. So instead of indulging in more cheque-book engineering, I had a look at what could be done with a little ingenuity.  Ingenuity is, afterall, the root of the noun 'Engineer'.

The first experiment was to remove the inlet filter from my shop air compressor and fit a hose adapter. It worked, it pulled a deep vacuum. Unfortunately, it also sucked the oil mist out of the sump and dumped it the reservoir tank. It was clear I needed a oil-free vacuum pump. A search on e-bay turned up an inexpensive 12 volt truck sized tyre (tire !!!) inflator for less than £12 delivered. The pump was rated at a whopping 35 L/min and 150psi, which might be a bit optimistic.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070059.JPG)


I did not actually want a pressure pump, so I dismantled it to locate the inlet valve. The inlet valve was found to be a steel reed valve mounted on the top of the piston. There was no way of connecting to the inlet with the reed valve in it's current position, so I drilled some holes in the cylinder head and repositioned the reed valve. See the before and after shots below.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070060.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070062.JPG)


The inlet port in the piston was sealed with a screw in plug and a hose barb was screwed into the cylinder head.  Voila, I now have a low cost vacuum pump which works. I do not have a vacuum gauge, so I cannot tell you how many inches of mercury,  but it sure sucks well. It also has the advantage that it is still capable of inflating tyres.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070061.JPG)


I still needed a vacuum chamber for degassing. So it was back to some kitchen chemistry for this. I obtained an ancient aluminium steam pressure cooker. It was robustly constructed with a domed aluminium lid, held down by a handwheel and a stout strongback. The aluminium lid was replaced with a see-through lid made from 8mm polycarbonate (a recycled police riot shield). A sheet of 3mm sticky back nitrile rubber was cut to shape and forms the vacuum seal.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070064.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070072.JPG)


I would have prefered to use a thicker piece of polycarbonate for the lid but none was available. Hopefully, there may not be too much of a problem with the lid bowing inwards because the handwheel and the strongback can be used both to energise the rubber seal and then support the lid to prevent excessive bowing. We will see!!

Total cost of my DIY degassing rig.... less than £15. I hope it works.

Mike

Title: Re: By Jupiter
Post by: Roger B on February 28, 2018, 06:14:32 PM
Looks good to me  :ThumbsUp:  :ThumbsUp: I'm glad to see the happy mug is there and that your garden is not under two feet of snow  :)
Title: Re: By Jupiter
Post by: MMan on February 28, 2018, 08:45:05 PM
Gotta ask, where did you find  a secondhand riot shield?

I hadn't realised they were 8mm thick either.

Best regards,

Martin.
Title: Re: By Jupiter
Post by: Vixen on February 28, 2018, 08:56:44 PM
Gotta ask, where did you find  a secondhand riot shield?


Years ago, bought at Harry Pounds scrap yard on the way into Portsmouth. Knew it would come in useful one day

(Or perhaps it was on the side of the road after a Southampton v Portsmouth football match............. Can't remember)

Mike
Title: Re: By Jupiter
Post by: Brian Rupnow on March 01, 2018, 01:23:02 AM
Mike--You are doing some marvelous work there. I understand the science behind what you are doing, but the practical application is way beyond my skill set. Thank you for the great pictures and documentation.--Brian
Title: Re: By Jupiter
Post by: petertha on March 01, 2018, 07:21:00 AM
Looks like you have it nailed

I used to do quite a bit of composite work (high performance RC models, molds & such). I already had a vacuum pump for bagging & read about people reconditioning kitchen pots with gaskets & such. Eventually I landed on some ebay suppliers, likely Asian made & re-distributed. I bought one like below & they are dead simple plug & play. Depending on your molding fluids (resins, urethanes, silicones...) you likely have to allow for the bulk foaming effect. It rises like a sponge, then collapses into a bubble free degassed mix, which is what you want. Also its nice (mandatory?) to have a relief valve & see through lid. I've attached video below. Particularly with faster cure time mixtures, you want to get your goop properly mixed, straight into the chamber, de-gas & commence application. The more viscous the mixture, the higher propensity to hold bubbles. If you don't mix the A&B properly trying not to create bubbles , you have bigger headaches.

https://www.ebay.ca/itm/BACOENG-2-Quart-Mini-Stainless-Steel-Extraction-Degassing-Vacuum-Chamber/162328539488?hash=item25cb88f160:g:i-oAAOSwmRFaZVVf

There are decent vac pumps out in ebay land too. Yes the oil is something to be aware of, depending on the specific compressor & how you've rigged it, any carryover as small vapor mist can mess up your mixture chemistry & adversely affect cure properties so beware. Also, the hardener/catalyst component of some mixtures, particularly epoxy's & urethanes can adversely react with some of the pump internals. I used to hear this a lot with 'repurposed' compressors, either the seals breaking down or other issues hey weren't service rated for. Again, more money but decent vac pumps are available & generally cheaper than they were years ago,
https://www.ebay.ca/itm/5CFM-Vacuum-Pump-2-Stage-1-2-Hp-Rotary-40Miron-Wine-Degassing-HVAC-Auto-AC/292433929614?hash=item44166ba58e:g:6kEAAOSwWEZadCS1


bbSvzD8g_S0
Title: Re: By Jupiter
Post by: Vixen on March 01, 2018, 10:22:59 AM
Hello petertha,

Thanks for your reply. I now have a much better understanding of the degassing process, thanks to the video.  :ThumbsUp: :ThumbsUp:

I appreciate that the equipment I put together is very rudimentary, but I only have one more set of silicone moulds to make. Hopefully it will last long enough for that.

I have checked on evil-bay and can find similar pots and vacuum pumps, all manufactured in China, often with 'free' delivery to the UK. If I get serious and find I need better equipment, then I know it is easily available.

Thanks again

Mike
Title: Re: By Jupiter
Post by: Vixen on March 06, 2018, 12:14:40 PM
The lost wax casting saga continues.

The snow has long gone and I am out of hibernation again. So, time to construct some one-shot mould boxes out of Plasticard and to mix and pour the silicone resin around the three core patterns for the Jupiter's Induction Manifold.

Also a chance to try out the new degassing rig made from a modified, oil-less tyre inflation pump and a recycled pressure cooker pot.

The degassing worked very well. The improvised vacuum pump pulled a good vacuum. I do not know how many inches or pounds because the vacuum gage had not yet arrived in the post. I degassed the silicon in the mixing jug several times until the goop stopped expanding and most of the bubbles had burst. When the degassing had slowed, I gently poured the silicone into the three mould boxes and degassed again. The silicone resin is very stiff and so the entrapped bubbles take a long time to rise to the surface by their buoyancy. It is amazing to see how much air there is in the mixed silicone resin.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070077.JPG)

The Silicone resin takes 12 hours to cure and this is done at normal atmospheric pressure, which collapses any remaining microscopic air bubbles to zero.
Here are the three mould boxes next morning. Together, they hold a kilogram of silicone. the triangles at the corner of each box are to economise on the quantity of expensive silicone. The white plastic tubes sticking out of the moulds will be used to align both mould halves after they have been cut open.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070078.JPG)

You will all have to wait to see if the patterns release from the silicone, or whether I have three, big, expensive, pink, blocks of rubber with the patterns firmly glued inside.

Mike



Title: Re: By Jupiter
Post by: Hugh Currin on March 06, 2018, 05:03:40 PM
Mike:

Great work and beautiful parts. The mold making and investment casting is very interesting. I've always thought of investment casting as way too expensive to consider. Nice to see there are some firms who will do small volume orders. Food for thought.

I haven't done any of this but did a little bit of research. I think one can use pressure during cure to "shrink" bubbles. Just compressing them decreases their size. This may have been for resin parts in a silicone mold. Should work for the mold itself though? May be ahead applying vacuum during cure as you did, I don't know. But might work to pull a vacuum on the poured mold followed by pressure?

I remember seeing vacuum pumps for fiberglass work. Vacuum bagging mainly. Of interest because they are made to work with resin fumes. I looked at my old source, FiberGlast, and found some. But they are commercial and really expensive. I remember they had a less expensive unit, but that was 20 years ago. They do have a venturi vacuum generator. (https://www.fibreglast.com/product/high-efficiency-vacuum-generator-02229/Vacuum_Bagging_Pumps) Hook it up to a air source and it generates a vacuum. Don't know how well they work, and this one still expensive, but they do exist.

Again, thanks for the build log. Am following along.

Hugh
Title: Re: By Jupiter
Post by: Jasonb on March 06, 2018, 06:02:45 PM
Hope they come out alright in the morning.

I have one of the small vac pumps from Bagpress which I use for veneering and laminating.

(http://img.photobucket.com/albums/v156/jasonballamy/work/IMAG0038.jpg)

And also the odd bit of thermo forming of corian.

(http://img.photobucket.com/albums/v156/jasonballamy/corian.jpg)

(http://img.photobucket.com/albums/v156/jasonballamy/z22.jpg)
Title: Re: By Jupiter
Post by: petertha on March 06, 2018, 08:34:58 PM
I think one can use pressure during cure to "shrink" bubbles. Just compressing them decreases their size. This may have been for resin parts in a silicone mold. Should work for the mold itself though? May be ahead applying vacuum during cure as you did, I don't know. But might work to pull a vacuum on the poured mold followed by pressure?
Hugh

Yes, that is something you see quite often in composites work, very often as a combination of other processes.
- Vacuum: to conform the layup resin/cloth to the mold, particularly complex shapes. Also in the case of sandwich construction where the cloth is bonded to an intermediary core material, foam, balsa, hex etc. It also works in conjunction with peel ply, a porous fabric or film that bleeds excess resin through in a regulated manner into a sacrificial wick layer for a light layup.
- Pressure: to assist the vacuum which max's out at atmospheric 14.7 psi. So an added 20 psi gives net 34 psi
- Temperature: to assist cure (or absolutely required in the case of pre-pregs) & give added strength to resin

But getting back to pressure, for anything of volume like the unit shown, you start to get into some engineering. It has to have sufficient wall thickness to withstand pressure, typically compressed air. A typical air compressor tank is quite thin, but it just has small flange inlets for air in/out vs. a big opening to get your mix in & out of. So unless you want to be unscrewing lots of nuts on a flange, you are probably limited to lower pressures. When you see industrial autoclaves they are very substantial, essentially heavy wall pipe with domed end bells that look like submarines :) From a hobby standpoint a 'leak' in a vacuum is an aw shucks fssst... & some wasted resin. A leak in a pressure vessel can be more dramatic. I know we are talking 'low' pressure but just for fun, Google exploding 'home compressor tank' one day.

The issue with bubbles in a silicone or urethane semi-flexible mold is more about surface blemishes. Because its so viscous it makes it hard for gas (air) to escape. In the case of epoxy resins for layups, its more serious. it can compromise strength. But we can use a few tricks. Essentially the bubbles want to go 'up' to the lower pressure source. So its better to have lower hydrostatic head. That could mean flat dish with 1" height of resin, vs. a jar with 4" of resin. Or if space is a concern, do them in batches (providing you have sufficient cure time).

Looking forward to the metal bits. You are doing a fantastic job!
Title: Re: By Jupiter
Post by: Vixen on March 07, 2018, 07:30:34 AM
Hugh,
Thanks for calling by. Yes you are correct, lost wax casting of larger items can be a very expensive process. It is not just the expense in time to make the patterns and moulds, there is the expense of the materials, the silicone rubber, the soluble and hard waxes. Then comes the cost of the foundry. Lost wax casting for the model maker works best for small items such as steam fittings etc. Sometimes, there are larger parts, which are impossible to machine (like these Jupiter manifolds), then there are few options other than lost wax casting.

I think Petertha has answered the questions of vacuum then applying external pressure. It is good to hear how things are done in the big bad commercial world. That sort information is useful to the hobbyist, knowing that it can be done encourages further experimentation. It does emphasise what I said about the expense of this sort of work. A good commercial vacuum pump alone will cost several hundred pounds, dollars, whatever. Even that little 'Minipress' pump that Jason uses costs several hundreds.

Back to the Jupiter mould making. After degassing the silicone rubber with my ultra low cost modified tyre pump and pressure cooker pot. The silicone was allowed to cure overnight at normal atmospheric pressure. Next morning, the silicone had fully cured and it was time to open the mould boxes and cut open the moulds to remove the patterns. I was a little concerned that he silicone would not release cleanly from the patterns. I had used beeswax furniture polish as the release agent and was unsure how well it would work, if at all. I started by pulling apart the mould boxes and withdrawing the plastic alignment tubes. The mould boxes were made from plasticard sheet and the pieces will get recycled,

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070079.JPG)


The moulds were cut open along the centre line to remove the pattern pieces. The jagged cut line is intentional, the rough cut edges together with the two tubes, accurately realign the two halves
(http://lister-engine.com/coppermine/albums/userpics/10013/P1070080.JPG)

I was very pleased with the results. The silicon moulds were very crisp and sharp, without any sign of an air bubble. The pattern pieces released without the slightest problem. My rudimentary vacuum pump and degassing rig had achieved everything expected of it. It proves to me that a little ingenuity can be mightier than the cheque book.

Mike

Title: Re: By Jupiter
Post by: petertha on March 08, 2018, 12:49:12 AM
Beautiful! I'm glad everything worked. Just a few links for the notebook.

I don't work with silicones much, but have worked with their urethane cousins in various durometers. Both have their place which I wont get into. But both can be very fussy about what kinds of releasing agent one chooses. And I'm not talking about partial sticking, I mean the wrong choice can adversely affect the entire cure & become a real mess. You probably have some euro equivalent of places like this, they tend to be sculpture / special effects / jewelry making / bronze art casting type suppliers.
http://www.sculpturesupply.com/list.php

Finally found the place I got my vac chamber. Looks +/-$ similar to the ebay links from before
https://www.bestvaluevacs.com/categories/vacuum-chambers/aluminum-chambers.html

Maybe more composites orientated, but closer to home for you
http://www.easycomposites.co.uk/#!/resin-gel-silicone-adhesive/rtv-silicone-rubber/condensation-cure-mould-making-silicone-rubber-rtv.html

There are other vendors like Smooth-On & Alumilite that offer proven & compatible resins, sealers, release agents etc. But I think we beat this subject to death now. Molten metal time! :)

Title: Re: By Jupiter
Post by: Vixen on March 08, 2018, 12:22:26 PM
Hello Peter,

Thanks for all the insight into alternative materials, equipment and all the other techniques. It is all helpful in understanding the possibilities and alternative techniques. This understanding helps me refine my methods and equipment.

Here is a short summary the lessons I have learned so far, which may be useful to others contemplating making this journey.

I am using Polycraft GP-3481-F RTV Silicone Mould Making Rubber Shore A27. It is a Condensation Cure silicone rubber and therefore very tolerant of other materials. I have shown it is compatible with my perspex pattern materials, with grey primer paint, with Plasticard, liquid poly cements and beeswax furniture polish. This silicone will also self degas to a limited extent but can be improved with vacuum degassing.

I use a modified domestic pressure cooker pot as the degassing pot with a polycarbonate lid. It is almost identical to the $118 two gallon pots on your list.

I use a modified truck tyre inflation pump as the vacuum pump for my degassing rig. It  cost me £12 off evil-bay and it works well enough. If it should fail, the cost of a replacement is so low compared to a commercial vacuum pump, that I could replace it 10 times over. Commercial vacuum pumps can cost upwards of £200 -300.

I hope this will help others and show that with a little ingenuity, we can achieve similar results to much more expensive commercial equipment.

Thanks to all of you who have contributed to this project. I have learned so much, including how a vacuum bag will be useful (indispensable) when the time comes for me to laminate the airscrew.

Mike



Title: Re: By Jupiter
Post by: Vixen on March 14, 2018, 05:14:57 PM
It's soluble wax injection time for the cores of the Jupiter's Induction Manifold.

I obtained some different soluble wax for this batch of wax injection. As you can see, I bought 1lb block of Freeman Jewelers soluble wax from a UK supplier; Walsh's Jewellery Supplies. The new wax has a slightly lower melting point 165 to 170*F (75*C). It melts quickly, solidifies slowly and is very hard when at room temperature. It seems to be a good choice.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070085.JPG)

The colour takes a bit of getting used to but the finished waxes are very clean and precise. Warning, Children, please do not try to eat the engine parts.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070082.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070083.JPG)


While all this has been going on, I have made the external master pattern for the Induction Manifold using the same laminated perspex sheet method as before. The individual laminations were milled from 5.0mm perspex, The end flanges were similarly machined and everything cemented together with Tensol 12 cement in the same jig that was used to build the core patterns

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070055.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070056.JPG)


The laminated block was then carefully carved and filed to shape. It's a long, slow and messy process. Here are the external and core master patterns side by side.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070070.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070071.JPG)


I used 3mm and 5mm tall plasticard letters and numerals to add some detail to the casting.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070063.JPG)


This shot should give you an ideal of the size on the Induction Manifold. The wide angle lens distorts the image somewhat. The final image shows the master pattern sitting in the plasticard mould box awaiting the Silicone resin to be mixed and poured.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070081.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070084.JPG)


Mike

Title: Re: By Jupiter
Post by: petertha on March 14, 2018, 06:58:32 PM
They look fantastic, Mike.

When you got your casting quote(s) do you get the impression it was mostly of a function of volume like 3DP jobs, or is there a 'complexity' factor in there as well?
Title: Re: By Jupiter
Post by: Vixen on March 14, 2018, 08:17:13 PM
Hi Peter,

I use a company called 'Just Castings' located in the jewelry district in central London. They make two charges, one if for your share of the investment flask and the other is for the exact amount of metal used. Being a jeweler they charge for each gram of metal used. My Inlet Manifolds each consume 50.2 grams of aluminium. I am so glad I did not choose gold or platinum. Sounds strange, as we all buy our aluminium, or steel or bronze by the foot or metre length rather than by weight.

The investment process is quite involved and uses some specialist equipment. First your wax model is attached to a central wax Tree along with all the other wax models. The Tree is immersed in a flask filled with a ceramic investment slurry, (similar to Plaster of Paris), where it is degassed and allowed to set. The flask is then placed in a burn-out furnace and brought up to red heat over a period of twelve hours. The wax melts and the residues are vapourised by the heat. The metal for the casting is melted in an induction furnace, part of the vacuum casting rig. The red hot flask is transferred to the vacuum caster. The molten metal is automatically poured and a strong vacuum applied to the flask. The molten metal cools slowly filling every corner of the cavity in the investment flask. After a few minutes, to allow the metal to solidify, the hot flask is immersed in cold water which shatters the ceramic investment . High pressure water jets remove the remaining investment. The individual cast items are then cut from the Tree, the metal Tree is later recycled.

Just Castings prepare and cast several batches in different metal each day, sometimes you will wait a few days for a cost effective batch in aluminium, which is not a common jewelry material

Mike
Title: Re: By Jupiter
Post by: Tennessee Whiskey on March 14, 2018, 08:54:23 PM
Seems as if you are dealing with craftsman in the correct district; as this build is heirloom quality mechanical jewelry  8).

Cletus
Title: Re: By Jupiter
Post by: Vixen on March 14, 2018, 08:56:55 PM
Hi Cletus,

The only problem is they charge jewelry prices.

Mike   :'(
Title: Re: By Jupiter
Post by: Tennessee Whiskey on March 14, 2018, 09:05:19 PM
Yeah and they also know there isn’t a chance of the lady bringing it back in for a buyback if things go wrong  :old: 8). Seriously, your work is phenomenal.  :cheers: :cheers:

Cletus
Title: Re: By Jupiter
Post by: Vixen on March 14, 2018, 11:21:56 PM
Hay Cletus,

I have built a number of super detailed engines over the years, but this Jupiter is the biggest (over 1/3 scale) and by far the most challenging yet. It is taking me into some of those dark, unknown corners of engineering where more sensible model engine builders rarely go. I will admit, I will be pleased when this lost wax casting phase is finished and I can get back to more traditional model engine machining and building.

The last few months have been technically interesting, researching, experimenting with a different casting technique. Although I can truthfully say that I have hand crafted all the patterns; that I have cast the silicone rubber moulds and cast (injected) all of the waxes. It is a disappointment that I have been forced, through lack of equipment, know how, skill etc to subcontract the actual metal pouring to someone else. Lucky for me that I was pointed in the direction of Just Castings Ltd by Jason and Neil Wyatt. JCL made the last part trouble free, quick and reliable.

Mike
Title: Re: By Jupiter
Post by: Vixen on April 06, 2018, 08:00:14 PM
In Vixens Den springtime has arrived and the time has come to fit the Inlet Manifolds and the two Exhaust Stubs to the Bristol Jupiter Cylinder Heads.

My first task was to correct the rear face of the Cylinder Heads. I found they all needed to have 4.5mm cut off the rear face to match the Bristol's drawings. I managed to do this without using the camera to show an extra long 4mm diameter end mill cutting across the fins in a horizontal direction. You need to be very careful when re-machining cut fins, it is all too easy to catch an edge which usually results in a bent fin or two and lots of profanity.

The first photo shows a stripped down Cylinder Head being set up prior to drilling and tapping of the four 8BA screws which secure the Inlet Manifold to the rear of the Cylinder, the rear face has already been machined to size.  To my horror I found that two of the vertical fin slots coincide with two of the four securing bolt positions. To provide material for these two bolts, it was necessary to drill (mill) a 3mm dia hole between the offending fins and insert a 3mm dia aluminium dowel, secured with loctite. These two dowels can be seen on a latter photo

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070092.JPG)


The drill insisted in trying to wander off course in the fin slot, so I made a steel drilling jig plate to help steer the 1.8 mm tapping drill down between the fins and into the new dowel. I also made second jig plate with 2.2 mm holes to steer the 8BA tap.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070093.JPG)


It all worked out well and the Inlet Manifold bolted to the Cylinder Head perfectly.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070094.JPG)


Fortunately the Exhaust Stub bolt holes did not present any problems. Each Exhaust Stub is secured with four 8BA threads.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070095.JPG)


The final sequence of photos show the competition completion of today's session

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070099.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070101.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070103.JPG)

All I have to do now is to repeat this fiddly little job eight more times.

I will also order sufficient reduced head size 8BA bolts for the complete set of nine cylinders.

I will also lap in all 36 Inlet and Exhaust valves while the Cylinder Heads are being worked on. Another small step towards completion.

Mike

Title: Re: By Jupiter
Post by: zeeprogrammer on April 06, 2018, 09:21:00 PM
Wow. And 8 more to do! It is indeed very much a jewel.
 :popcorn:

The final sequence of photos show the competition of today's session

I don't know if you meant to say it that way...but I like it.  :Lol:
Title: Re: By Jupiter
Post by: Vixen on April 06, 2018, 09:33:24 PM
Hi Zee

Well spotted, sometimes I think I have a smell chucker instead of a spell checker the way it mixes up the worms.

Congratulations on reaching the Age of Retirement. By the way, all those chores you put off until retirement can wait a little longer. Celebrate your retirement by indulging yourself a little, take that promised vacation, make chips in the shop or whatever. DO IT FOR YOURSELF for a change.

Mike
Title: Re: By Jupiter
Post by: Dave Otto on April 07, 2018, 01:18:13 AM
Nice update Mike, it appears that the new parts are fitting up nicely.


Dave
Title: Re: By Jupiter
Post by: b.lindsey on April 07, 2018, 02:03:17 PM
I can't add much to what has already been said Mike but am still checking in regularly and learning a lot from your posts. All this meticulous work will certainly pay off in the end with a jewel of an engine.

Bill
Title: Re: By Jupiter
Post by: steamer on April 07, 2018, 03:57:56 PM
That looks great!
Title: Re: By Jupiter
Post by: Vixen on April 07, 2018, 04:28:18 PM
Hi Dave

How are things with you.? Are you healing well? It is always slower process when we get a little older.

Why not spend a bit of time behind the desk drawing up that Porsche 917 engine you started on a while ago?

Mike
Title: Re: By Jupiter
Post by: steamer on April 07, 2018, 05:48:15 PM
Hi Dave

How are things with you.? Are you healing well? It is always slower process when we get a little older.

Why not spend a bit of time behind the desk drawing up that Porsche 917 engine you started on a while ago?

Mike
Not a bad idea!

I'm walking short distances starting to strengthen the quad.   The surgical connection is good, just need the rehab.
Title: Re: By Jupiter
Post by: Tennessee Whiskey on April 07, 2018, 07:57:13 PM
Dave, mental, spiritual, or physical  :lolb: :lolb:. Sorry for the hijack

Cletus
Title: Re: By Jupiter
Post by: Craig DeShong on April 07, 2018, 11:20:34 PM
Mike.  I've open this thread, followed along, and closed it saying nothing.  Thus work is so extraordinary, I find a comment difficult, but thanks for showing me this amazing level of workmanship.
Title: Re: By Jupiter
Post by: steamer on April 08, 2018, 12:10:25 AM
Dave, mental, spiritual, or physical  :lolb: :lolb:. Sorry for the hijack



Cletus

Mostly physical.   
Title: Re: By Jupiter
Post by: Art K on April 08, 2018, 12:50:44 AM
Mike,
I've been busy in the shop myself getting Val ready for the NAMES show. Quite an elegant solution to the missing hole location. The interrupted hole is where I'd have been looking for an appropriate sized endmill.
Art

PS spell check only corrects wrong spelling not words. :lolb:
Title: Re: By Jupiter
Post by: Vixen on May 02, 2018, 02:31:13 PM
You can only put off some jobs on an engine for a while but eventually you to make a start. The case in point being the 36 valves on the Jupiter' s cylinder heads.

Each valve has a steel valve seat screwed into the aluminium head with a fine 40 TPI thread and a separate screw in phosphor bronze valve guide. Each valve is closed by a set of triple valve springs, just like the full size engine. The steel spring seat cups are grooved to keep the three valve springs concentric.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070099.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070120.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070118~0.JPG)


I used Loctite 572 Pipe Sealant to secure and seal the phosphor bronze valve guides into the cylinder heads. While the sealant was curing, I made up two sets of piloted valve seat cutters from hardened silver steel (drill rod). Two at 45 degrees for the working face and two 60 degree cutters with which to thin the sealing face from 1.5 mm to approx 0.7 mm.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070105.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070108.JPG)


Any valve seat cutter, no matter how well made, will always leave minute radial ridges and grooves on the surface, you may need to use a X5 eyeglass to see them, but they are there. It takes a lot of extra time to lap away these marks. I followed Terry Mayhughs method of using two cutters one after the other to produce a finer surface to the valve seat. The idea being the second cutter should flatten any ridges left by the first. Only the lightest of pressure is used with the second cutter.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070110.JPG)


The easiest way I found was to grip the valve stems with a small drill chuck. There is a short piece of soft aluminium tube between the chuck jaws and the valve stem to prevent the valves being marked.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070111.JPG)



In order to test the quality of the valve seat lapping it purchased this little hand pump vacuum tester. It can get to about  400 mm Hg (-15 inch Hg) that's about  -8 psi without too much problem from internal leaks. I cap off the top of the valve guide with a short length of silicon tube, and insert a rubber cork into the inlet/ exhaust port. I can create the vacuum by squeezing the trigger a couple of times. The internal volume of the volume under test is approx 3.9 cc. I can make the volume bigger (20cc) by connecting a longer pipe, but the short pipe is the most sensitive. I have set an arbitrary leak rate pass criteria of 20 to 30 seconds for the -8 psi to leak to zero. Consider the engine running at 2000 rpm, the combustion chamber pressure should be at over 200 psi during the compression stroke and much higher still during the firing cycle. At 2000 RPM that's a duration of somewhere between 20 to 30 milliseconds. So my leak test criteria (8 psi over 20 to 30 seconds) has an enormous margin over the running environment.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070115.JPG)


I experimented with several types and grades of lapping compound. I tried various grades of metal polish (as suggested by Terry Mayhugh) as well as different grades of silicon carbide made up as a lapping slurry  It quickly became obvious that it would become a trade off between time and quality of the gas seal.

Solvol Autosol uses pumice as the abrasive, Given time (hours) it will lap the valve and seats to perfect finish which can achieve my 20 to 30 second test criteria. This shows that polished valve seats will provide the best sealing possible, but it takes forever. However, some valve seats for whatever reason, just would not ever achieve a perfect seal, no matter how long I lapped with the metal polish, On these problem valves I tried ultra fine 600 grit silicon carbide. The seats lapped in quickly, but this lapping compound leaves a dull surface rather than a polished surface, sufficiently that a vacuum leak rate of over 10 seconds cannot be achieved, seems you need polished surfaces for a perfect seal. That was rather unexpected, as I have always used grinding paste on full size engines in the past to get an even all round matt finish, which always appeared to be adequate, I never had a vacuum tester. Our model engines have much small capacity so will be susceptible to any leaks. Especially an engine with four valves per cylinder.

I have just obtained some 1200 grip abrasive powder and will experiment further (there are plenty of valves in the Jupiter)  to find a workable compromise between the time require for a highly polished valves seal using metal polish against the quicker, but less perfect seal that come with abrasive lapping media.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070116.JPG)


Some suggest that fine diamond lapping compounds are the answer, but I worry about the diamond becoming embedded in the valves or seat faces and the long term effects on the seats and the rest of the engine.

Mike


Title: Re: By Jupiter
Post by: Admiral_dk on May 02, 2018, 08:32:38 PM
Great work and a very informative post, thank you very much :praise2:

I immediately got a few questions though ; are the full size valve guides and seats really screwed into place - I would have thought pressed / crimped (heat) ?

Do you not have too much "leverage" on the seat grinder, with a stiff handle so long (sixth picture) ...?... it looks to me that you easily change the angle from a perfect zero to a few arc seconds and therefore need more grinding afterwards  :noidea:

Where did you buy the pump ?

Best wishes

Per
Title: Re: By Jupiter
Post by: Vixen on May 02, 2018, 09:16:57 PM
Hello Per,

I am pleased you found these valve lapping experiments interesting. I try quantify my research and then hand on as much of my experiences to fellow members, as I can.

The full size valve seats were shrunk in place, using dry ice to shrink the seats and an oven to expand the cylinder head. Liquid nitrogen was not so readily available in the 1920's. The valve  guide would have been pressed in place. It is much more difficult to achieve the require interference fits at model size with model makers equipment, so making screw-in components is a very practical alternative solution. I have had a shrunk fit valve seat come loose in a full size race car engine and would not wish to have that happen again.

The seat cutter is piloted by a well fitting dowel inside the valve guide. The cutter also floats on two pins sticking out of the handle, it is not rigidly attached. Yes, you are correct, the clearance which allows the cutter to rotate around the dowel pin could, and probably does, lead to a few arc seconds of misalignment. Nothing is perfect. We can only do our best with the equipment at our disposal.

Everything in the world can be bought from E-bay in you know the correct description. Search for "Hand Held Vacuum Pump Brake Bleeder Tester Set" You will find many suppliers and they are amazingly inexpensive at about £12.

Mike

Title: Re: By Jupiter
Post by: Admiral_dk on May 02, 2018, 10:17:04 PM
Quote
Nothing is perfect. We can only do our best with the equipment at our disposal.

I'm very sorry if it sounded as a critique :embarassed: - I was thinking out loud - does this make it harder more work for you, than if you used a shorter distance from cutting edge to the handle .... besides I'm very impressed with your builds  :NotWorthy:
.... and I kind of figured that you had it made like the full size tool.

The only full size tool I have used had a very strong expanding "guide pin" (in order to ensure absolute alignment with the valve shaft), and the only difference to your seat cutter, was that the 3 cutting bits could be changed and that the handle was a bar directly on the backside of the cutting head. This made it virtually impossible to not achieve perfect alignment - this does not prevent user errors completely  :-[ .... (though I got it second try a few minutes later).
Title: Re: By Jupiter
Post by: Vixen on May 02, 2018, 11:53:37 PM
I'm very sorry if it sounded as a critique :embarassed:

That's not a problem with me, Per. We can all learn from discussions, like this one, between informed engineers.

The actual seat cutters, both the 45* and 60*angle cutters, are only 12 mm long, the two pins protruding from the handle act like a universal joint, therefore should not adversely affect the alignment of any of the seat cutters with respect to the valve guide axis. By definition, there must be some minimum clearance between the the cutter and the dowel or "guide pin" to allow rotation. I will look to see if this can be improved as there are still an number of valves yet to be lapped in. It may be fun trying to make a "very strong expanding guide pin" from a pin which is only 3.1mm in diameter.

On reflection, it would have been better to machine the valve seat face and valve guides in one combined operation, while the cylinder head was still on the milling machine, Perfect concentricity would have been achieved.  Unfortunately that opportunity occurred some years ago, so it's damage limitation today.

I am trying to develop a reasonably quick method of valve lapping which overcomes any minute build imperfections.

Mike
Title: Re: By Jupiter
Post by: b.lindsey on May 03, 2018, 12:46:04 AM
Amazing work Mike. How difficult was it to get each set of concentric valve springs the same length, or is there some leeway in that?

Bill
Title: Re: By Jupiter
Post by: Vixen on May 03, 2018, 08:47:51 AM
The triple valve spring arrangement is true to the original Bristol Jupiter design. In the model engine the outer spring does about 70% of the work, the inner two springs are very light and can easily be stretched to the required length. Did you notice the middle spring is wound in the opposite direction to the other two? This is to stop the springs becoming coil bound during compression.

The use of three springs per valve was more to do with avoiding harmful resonances than high closing forces. Roy Feddon, the chief designer at Bristol's, would only use Swedish steel for the valve springs.

Mike
Title: Re: By Jupiter
Post by: petertha on May 04, 2018, 07:17:21 PM
Beautiful work Mike. I knew you would find Terry's work beneficial.

Re your seat cutter, do you mean you cut the teeth profiles from annealed tool steel & did hardening & post dressing yourself? Or you managed to cut them from pre-hardened stock?
Reason I ask is I bought the 45-deg multi-flute tool Terry & others had good experience with, a muzzle seat... something-er-other (sorry I'm not a gun guy). It is very sharp & does an excellent job, but the trick I found is the slightest of applied pressure. I think someone mentioned the weight of the cutter body itself. Otherwise what happens is the cut develops kind of its own kind of non-linear cyclic wavy profile that feeds on itself & gets progressively worse as you hand turn the tool. Maybe this is a slow speed version of what's happening when harmonic chatter occurs with countersinks etc. Anyway, I always wondered if an odd or staggered tooth set might help?

I made up two sets of piloted valve seat cutters from hardened silver steel (drill rod). Two at 45 degrees for the working face and two 60 degree cutters with which to thin the sealing face from 1.5 mm to approx 0.7 mm

Title: Re: By Jupiter
Post by: Vixen on May 04, 2018, 08:59:52 PM
I have moved further valve lapping discussions from the "By Jupiter" build log to the existing "Valve grinding and lapping" topic, so that everything is under one roof,
This move should make searching easier in the future.

http://www.modelenginemaker.com/index.php/topic,8006.msg173066/topicseen.html#new
Title: Re: By Jupiter
Post by: Vixen on May 25, 2018, 03:02:30 PM
Time for an update on the Jupiter build.

My recent work has been directed towards finishing the cylinder heads and getting them to a ready to run state. The cylinders were all removed from the engine core so that each task could be completed on each of the nine cylinders, before moving on to the next.  Below, you can see the naked engine core and the propeller speed reduction gearbox. The inlet and exhaust pushrods are standing vertical. The rocker box location rods have been folded forward for convenience.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070125.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070127.JPG)


There was a reasonable amount of work to do on each of the cylinder heads. The rear (inlet manifold) face required 4.5mm to be removed to correct the profile. The mounting holes for inlet manifold and exhaust stubs were drilled and tapped 8BA. The valve guides were screwed in place sealed with Loctite 572 pipe sealant. I will not use screw-in valve guides again, the thread clearance is enough to upset the concentricity of the valve seat and valve guide. A press fit valve guide would have been much better.

Each of the 36 valves was lapped in and tested with a vacuum leak tester. I started by using Autosolv metal polish, This proved to be excessively time consuming. I next tried 600 grit silicon carbide, which was much quicker but did not give the best leak test results. Finally, I obtained some 1200 grit green silicon carbide powder from a jem stone polisher. The ultra fine powder was made into a paste with mineral oil and a little white spirit. The ultra fine abrasive powder worked well, each of the valves was lapped reasonably quickly and all were able to pass a full 30 second leak down test.

Nine cylinders, 36 valves, 108 valve springs, 18 exhaust stubs and 9 inlet manifolds later, we see the completed cylinders having a 'Team Talk before the big Match'

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070133.JPG)


The cylinders were returned to the engine core. The cylinder heads are starting to look fully dressed with the manifolds and exhaust stubs in place.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070136.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070137.JPG)

Stay tuned

Mike

Title: Re: By Jupiter
Post by: Stuart on May 25, 2018, 03:08:26 PM
Mike

One word. Wow that sure does look the bees knees

Great work
Title: Re: By Jupiter
Post by: zeeprogrammer on May 25, 2018, 03:26:12 PM
I'll use the same word. Wow!
And again...wow!!

That is really impressive work.  :ThumbsUp:
Title: Re: By Jupiter
Post by: sco on May 25, 2018, 03:38:04 PM
Damn that looks good!

Simon.
Title: Re: By Jupiter
Post by: crueby on May 25, 2018, 05:43:59 PM
Whatever is beyond Wow, thats the word!
Title: Re: By Jupiter
Post by: Craig DeShong on May 25, 2018, 07:08:27 PM
I am at a loss for complimentary words.  :Love:
Title: Re: By Jupiter
Post by: Admiral_dk on May 25, 2018, 09:18:50 PM
Quote
I am at a loss for complimentary words.  :Love:

Me too ....
Title: Re: By Jupiter
Post by: metalmad on May 26, 2018, 01:52:34 AM
Absolutely Beautiful  :praise2:
Title: Re: By Jupiter
Post by: Mayhugh1 on May 26, 2018, 02:42:57 AM
I just happened upon your build. I went to the beginning and started reading and couldn't put it down until I had read it completely through. I'm awe struck. A really impressive project and excellently written up as well. I loved the photos and text associated with your casting process - Terry
Title: Re: By Jupiter
Post by: Jasonb on May 26, 2018, 07:03:33 AM
Those cast manifolds do look the part :)

No that you have found a suitable foundry do you think you may be getting more parts done that way which you had previously intended from solid provided the piggy bank allows it? Or will you just use it where it would be hard to do from solid unless parts were joined together.
Title: Re: By Jupiter
Post by: Roger B on May 26, 2018, 07:17:58 AM
Splendid  :ThumbsUp:  :ThumbsUp:  :wine1:
Title: Re: By Jupiter
Post by: Jo on May 26, 2018, 07:43:10 AM
Its only six Weeks until the GMES show Mike, we are expecting to see the Jupiter there  :)

Which reminds me... was I going to take anything this year as they didn't invite me to :noidea:

Jo
Title: Re: By Jupiter
Post by: Jasonb on May 26, 2018, 07:45:57 AM
Maybe as you run them down so much they did not invite you?

I got an invite ;)
Title: Re: By Jupiter
Post by: Vixen on May 26, 2018, 08:40:37 AM
Wow! Thanks for the encouraging comments.  :ThumbsUp: :ThumbsUp:

Jason, Lost wax casting has it's place. It is ideal for making highly detailed small items like boiler fittings, or higher volume runs of intricate engine parts. I am thinking of Bruce Satra's Morton and P&W engine castings or the RR Merlin castings used by Terry Mayhugh. If you read Terry's Merlin build log, he tells how he needed to straighten warped castings and having to spot the fastener centers off the casting to ensure good visual alignment.

I consider lost wax casting to be the weapon of last resort. I would prefer to carve an intricate part from a solid billet whenever possible. Sometimes a part is impossible to carve, rather than simply difficult and that is where the lost wax casting process comes in. However lost wax can be an exercise in frustration, time and expense, but if there is no other way.....

Jo I have displayed at the GMES show for over twenty years and have the pile of their little brass plaques to show. They invited me again this year, provided I brought my own tent and removed the display each night. They could no longer provide any insurance cover. I plan to bring the Jupiter and the Mercedes W165 engines. I will be sharing a gazebo tent with Mike Cole.

Mike
Title: Re: By Jupiter
Post by: Vixen on June 08, 2018, 01:47:53 PM
How do the words of that John Denver song go; "Some days are diamonds, Some days are stone".

The Jupiter project can be a bit like that and "Some days are stone"

I have had a few frustrating days with the Jupiter, trying to cast the investment wax for the induction manifold which connects the carburetors to the Induction Spirol. I have never attempted anything this big before. The first couple of attempts were a disaster. I find I am not getting complete filling of the mold cavity, probably due to premature cooling of the wax before it had flowed completely round all three tubes. It could be a trapped air pocket or the wax is cooling too quickly before all the molten wax has been injected. The wax is crumbly and crystalline which again suggests chilling. Maybe I need to find a way to heat the silicone mould before injection. The front side, which is not visible, is almost perfect but the rear face, which can you, see is flawed.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070159.JPG)
Here are the three soluble wax cores waiting inside the mould cavity for the hard wax injection

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070145.JPG)
The mould box still clamped up after the red wax injection

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070147.JPG)
The first disastrous attempt

It is very expensive in time and materials, I need to sort this problem quickly. I will start by adding some more air vert holes and if that does not work, to inject the wax from the opposite side to get the hottest wax flowing against the part you see. I have also got a different type of injection wax to try. The problem is it's a three day cycle, The yellow soluble wax cores are made on the first day and the hard wax injected on the second and the cores are dissolved out on the third.


(http://lister-engine.com/coppermine/albums/userpics/10013/P1070150.JPG)
The second attempt was a little better but still incomplete filling

I made some changes to the procedure. I changed the injection point to the other side, so the hot molten wax will flow over the problem side first, I already added the three small air vents but the biggest change was to use a different kind of wax with a lower melting point and less fillers than the red wax. It is not so strong due to the absence of any fillers but it worked well enough, as you can see.in the photos. The green wax casting is not perfect, but it is adequate to cast from. The yellow soluble wax was dissolved out overnight in cold water. If you look, you can see the white and black plastic inserts I used to economise on the amount of the expensive soluble wax consumed each time.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070153.JPG)
Things look promising when I open the mould box


I warmed the mould over an old oil filled radiator, I could only go to a few degrees above ambient because any higher and the soluble wax cores start to melt, and there could be thermal expansion problems with the silicone moulds. Any way, the mould was warmer. I also changed the type of wax, the red wax was high temperature melting (and cooling) which I suspect was being chilled by the mould. I found some lower temperature green wax, with less filler materials, which was much more fluid when ready to inject. That, together with the additional air vents and injecting the wax from the other side of the mould all paid dividends. I have one usable green investment wax, not perfect, but usable. It's in the cold water tub at the moment dissolving the three cores. Tomorrow I will be able to inspect the complete wax. You may notice one of the bolt flanges broke off during removal from the mould. It was a clean break, so I can repair that easily in the morning. I have discovered that LiquidPoly plastic kit glue will solvent weld investment wax almost invisible.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070155.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070157.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070156~0.JPG)


I have just enough materials left to have one more attempt to try and improve the wax model. I will send the best one to the foundry and have the other in reserve in case there is a foundry disaster. Hope I will not need it !!!


Gotta go, got a hot date with a sexy   wax model
Title: Re: By Jupiter
Post by: petertha on June 08, 2018, 05:29:09 PM
I admire your tenacity, those are complex pieces. What 'dissolves' the inner core yellow wax & leaves the shell wax unaltered?
Title: Re: By Jupiter
Post by: Vixen on June 08, 2018, 05:50:04 PM
The soluble "wax" is formulated to be just that, ie. soluble in cold water. It needs to be kept in an airtight container. The shell wax formulation is different and completely unaffected by water. Both melt below the boiling point of water and both become a solid at room temperature. Both are expensive consumables on the road to a metal casting. The different wax formulations are died with colour to help identification.

Mike
Title: Re: By Jupiter
Post by: petertha on June 11, 2018, 07:12:59 PM
The soluble "wax" is formulated to be just that, ie. soluble in cold water.

Interesting. I had no idea that was even available. Can you provide me a brand name or supplier (its completely unrelated to casting).

Back to your project, apologies if you addressed or answered this somewhere already. But would a 3D-printed hollow part (essentially the part itself) serve the same purpose as the 2-part wax core process if it was printed in casting wax? I have 3D cad experience but limited 3DP experience aside from a few plastic knick-nacks made for me at Shapeways. I see specific waxes being offered as a material selection for jewelry & the like.
Title: Re: By Jupiter
Post by: Vixen on June 11, 2018, 09:01:04 PM
Hi petertha,

In Reply # 86, I gave details of suppliers in UK and USA where you can obtain Freemans Jewelers Sol-U-Carve wax. There are alternative brands, but this is the one I used.

There are many roads to heaven and as many ways to produce an investment wax. Of course it is possible to create a 3D model of the part and get the likes of Shapeways to print a wax for you.

A number of print houses will also provide the complete lost wax castings process, limited to small items. You send the 3D model file together with the money and they send back the metal casting.

Some people say you can print a PLA model on your home printer and go for lost PLA instead of lost wax. It sort of works, but I have yet to see a quality casting using this method

My 3D modeling skills and home computer power are limited, so I chose to make physical master models, moulds and cast my own investment waxes. I still need to employ the services of a lost wax investment foundry to do the final stage of casting the aluminium.

Mike
Title: Re: By Jupiter
Post by: 90LX_Notch on June 11, 2018, 10:47:04 PM
I am beyond impressed with this thread.  Great stuff Mike; keep it coming.

-Bob
Title: Re: By Jupiter
Post by: Art K on June 12, 2018, 03:37:38 AM
Mike,
Those parts look great, like everyone else I lack all the terms saying how phenomenal those wax castings look. Still following along.
Art
Title: Re: By Jupiter
Post by: Vixen on June 12, 2018, 10:45:53 AM
Thank you all for following and your kind comments

The Induction Manifold investment wax has arrived at the foundry and is "in process". I have my fingers crossed waiting to see what emerges.

Mike
Title: Re: By Jupiter
Post by: Jasonb on June 22, 2018, 04:25:52 PM
Have you got any goodies back yet? and I don't mean the free sweets.
Title: Re: By Jupiter
Post by: Vixen on June 22, 2018, 08:18:09 PM
I was talking with the foundry today. The Induction Manifold has been cast, I have just paid for it and it should now be in the first class post on it's way to me. I had to pay the cost for a complete investment flask as my casting was too large to share the flask space with other customers. So if you see me limping, you will understand it cost an arm and a leg.

While I was waiting, I decided to make some chips...... lots of chips.
I started with a couple of 2 inch by 2 inch by 2 inch blocks of 6084 aluminium with the intention of making a pair of Magneto front housings.  The Jupiter was fitted with a pair of BTH SC9 nine cylinder magnetos mounted on the rear face of the engines crankcase. The first opp was to machine the mounting flange, the bearing housing and to drill and tap all the mounting holes; all at the same setting, so everything should be nice and concentric.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070163.JPG)

The embryo magnet housings were attached to a fixture plate, held in the machine vice, so that the main part of the two housings could be machined. As you can see most of the two aluminium blocks disappeared into a mountain of chips. Fortunately, there was a magneto housings hidden inside each block.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070164.JPG)

This is as far as I have got. The magneto housings are nearly finished but I have discovered the rear cover for the crankcase cover will need to have some additional material removed from both magneto mounting flanges before everything will fit together. There's always something that does not quite fit.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070165.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070166.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070167.JPG)

Stay tuned

Mike
Title: Re: By Jupiter
Post by: Art K on June 22, 2018, 11:07:07 PM
Mike,
The Magneto housings look great. I look forward to seeing the manifold.
Art
Title: Re: By Jupiter
Post by: steamer on June 23, 2018, 12:13:18 AM
That looks awesome Mike!
Title: Re: By Jupiter
Post by: Dave Otto on June 23, 2018, 01:02:49 AM
Beautiful work Mike!

Dave
Title: Re: By Jupiter
Post by: steam guy willy on June 23, 2018, 01:42:58 AM
Lovely work here.....lots to aspire to

Willy
Title: Re: By Jupiter
Post by: Vixen on June 23, 2018, 04:37:17 PM
Thanks guys for looking in and saying hello.

Thanks also to Jo for accidentally deleting this post first time around.   :killcomputer:

The postman, bearing wondrous gifts, knocked on the door early this morning. For once, I did not mind getting up to sign for the package for it contained the final casting from 'Just Castings',  the Induction Manifold for the Jupiter engine. They had done another excellent job with this casting, as I have come to expect from them. It needed only a few strokes with a fine file to clean up the flange faces ready for a final skim cut on the mill. I still need to clean up the inflow risers and a few other blemishes, but really there is very little work required.

(http://lister-engine.com/coppermine/albums/userpics/10013/CAP1~1.jpg)
This is an image of the full size item taken from the works manual.



(http://lister-engine.com/coppermine/albums/userpics/10013/P1070168.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070169.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070170.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070171.JPG)

As you can see, it's quite a large casting and consists of three separate passages from the three barrel carburetter to the rear of the engine. The typical wall thickness is between 1.5 and 2.0 mm. 'Just Casting' inform me it consumed 123.5 grams (about 5 ounces) of aluminium, being jewelers, they always charge for the metal by the gram. I am pleased I did not ask for silver or gold.

It has been a long interesting journey into areas unknow and I am very pleased with the result.

Happy, happy, happy

Mike
Title: Re: By Jupiter
Post by: Jo on June 23, 2018, 04:47:50 PM
Sorry Mike  :toilet_claw:



It does look rather nice  :embarassed:

Quote
Happy, happy, happy

Does that mean you have got over the cost Mike  :)

Jo
Title: Re: By Jupiter
Post by: Vixen on June 23, 2018, 04:58:33 PM
Hi Jo,

Not a problem, but don't make a habit of it. :lolb:

As for the cost, it's only the kid's inheritance after all, and I got to spend it before them. :LittleDevil:

You know, they did not include any candies this time, may not use them again.

Cheers

Mike
.
Title: Re: By Jupiter
Post by: Jo on June 23, 2018, 05:14:24 PM
You know, they did not include any candies this time, may not use them again.

Phone them up and tell them that your grandson was very disappointed with not getting his sweeties this time - I am sure that a company like that with a reputation to maintain will oblige  ::)

I hate to think what each sweet cost you  :facepalm2:

Jo
Title: Re: By Jupiter
Post by: Dave Otto on June 23, 2018, 06:47:47 PM
The casting looks great Mike.

Dave
Title: Re: By Jupiter
Post by: Roger B on June 23, 2018, 08:13:45 PM
Splendid work (as ever)  :praise2:  :praise2:  :wine1:
Title: Re: By Jupiter
Post by: fumopuc on June 23, 2018, 08:28:59 PM
Hi Mike, impressive, as always.
Title: Re: By Jupiter
Post by: Craig DeShong on June 26, 2018, 12:39:01 AM
This project continues to amaze me.  I may have to make a trip to the UK just to see it when you get it done !

On a side note, every wonder what these jewelry makers are thinking about the work you're asking them to do?
Title: Re: By Jupiter
Post by: zeeprogrammer on June 26, 2018, 12:42:57 AM
This project is certainly in that class of "I'll never get there but 'boy' wouldn't it be nice?".

In any case... I'm learning things and that's invaluable.
Title: Re: By Jupiter
Post by: crueby on June 26, 2018, 01:00:13 AM
Wow. Was looking at the casting, thinking it looked great, then spotted the coffee cup and realized how small it is. Very nice! Great job on the molds, was well worth the extra tries.


 :popcorn:
Title: Re: By Jupiter
Post by: Vixen on June 26, 2018, 11:53:41 AM
Thanks everybody for calling by and saying hello  :ThumbsUp: :ThumbsUp:

I made some measurements to determine the actual shrinkage rates at the various stages. The master patterns were made 3% oversize. Silicone rubber was cast over the master patterns and the wax model was cast (injected) into the silicone mould. The wax model had shrunk slightly and was now a little over 2% oversize. At the foundry, they cast the investment slurry (looks like Plaster of Paris) over the wax model together with the wax runners and risers. The wax was burned out over a 12 hour period raising the investment flask to red heat. The molten aluminium was drawn into the heated investment mould cavity using a special vacuum caster. The finished aluminium casting was measured to be between 0.5% and 1% oversize. I am happy with this, a slightly oversize casting is always preferable to undersize. If I go down this route again, I will start by making the master patten 2.5 % oversize instead of 3%.

Craig, model engine parts were something new to my jeweler, the were very enthusiastic and helpful and keen to add model engine parts as a new business opportunity.

Zee, with lots of practice you will learn and gain experience. You can then use your experience to make the same old mistakes as last time, but with greater confidence than before.

Mike
Title: Re: By Jupiter
Post by: Admiral_dk on June 26, 2018, 10:39:07 PM
Quote
You can then use your experience to make the same old mistakes as last time, but with greater confidence than before.

 :ROFL: :lolb:  Thank you for that one Mike - I needed a good laugh. + I'm sure it WILL happen to me again sometime  :insane:

Oh, and I do still enjoy your fantastic journey with this jewel  :praise2:

Per
Title: Re: By Jupiter
Post by: Art K on June 26, 2018, 11:24:02 PM
Mike,
I also noticed the coffee cup, great for scale. :lolb:
Quote
with lots of practice you will learn and gain experience. You can then use your experience to make the same old mistakes as last time, but with greater confidence than before.
Remove Zee insert own name. :ROFL:
Looks great.
Art
Title: Re: By Jupiter
Post by: zeeprogrammer on June 27, 2018, 12:55:18 AM
Quote
with lots of practice you will learn and gain experience. You can then use your experience to make the same old mistakes as last time, but with greater confidence than before.
Remove Zee insert own name. :ROFL:

Might work for you all...but not for me. Zee = Zee.

Wonderful quote.  :ROFL:
Title: Re: By Jupiter
Post by: Art K on June 27, 2018, 05:24:29 AM
OK be that way, but I still like the quote. :lolb:
Art
Title: Re: By Jupiter
Post by: Vixen on June 27, 2018, 10:40:51 PM
I have completed some initial cleaning up of the Induction Manifold using a sharp file and the Dremmel. I will complete the final surface finishing when all the other work is completed on the manifold.

The first thing I wished to accomplish was to attach the Induction Manifold to the rear of the engine. This required some more fabrication work on the Rear Cover to add three inlet stubs. The Rear Cover had previously been manufactured some time ago. It was straight forward turning work for a large lathe, in this case it was turned on a rotary table using a ball mill to contour the outside and inside curved surfaces.

Here is an image, from my works handbook, showing, left to right, the rear of the Crankcase, the Induction Spirol and the Rear Cover. I will discuss the Induction Spirol later.

 (http://lister-engine.com/coppermine/albums/userpics/10013/Induction_spirol_1.jpg)




I machined up the three inlet stubs, complete with the mounting holes and super-glued the stubs to the Induction Manifold. This allowed me to accurately transfer drill the 12 mounting holes into the flanges. Then I co-ordinate drilled a simple fixture plate to hold the three inlet stubs in the correct orientation. Using this fixture, I was then able to profile the curved surface with numerous passes with a 8mm ball cutter. The super glue joint holding the stubs to the manifold was easily undone with a sharp tap with a small hammer.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070177.JPG)



After profiling the mating face, the three inlet stubs were permanently bonded to the Rear Cover using JB Weld epoxy. The 12 mounting studs and six more additional countersink screws were drilled and tapped through both the inlet stubs and Rear Cover to make a very strong and permanent assembly

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070182.JPG)



A full set of 12 8BA studs were made and secured in place. Miraculously all 12 studs lined up with the holes previously drilled in the Induction Manifold flange.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070183.JPG)
(http://lister-engine.com/coppermine/albums/userpics/10013/P1070184.JPG)



Here we can see the Rear Cover and Induction Manifold nestling neatly at the rear of the engine, with the 'accessories' gearbox in the center of the Spirol. That big Induction Manifold casting is beginning to look quite small on the back of the mighty Jupiter engine

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070189.JPG)



The Bristol Jupiter MK VIII was un-supercharged, instead, it had a unique (patented) Induction Spirol buried in the rear of the crankcase. It's purpose was to distribute the fuel mixture from one of the three carburetter barrels to three cylinders. The spiraling airflow was designed to keep the fuel/ air mixture in constant motion and so prevent it separating into droplets. The numbers cast on the back of the Induction Manifold are there to tell the maintenance engineer which cylinders relate to which carburetter barrel.

More on the Induction Spirol later.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070188.JPG)



Stay tuned

Mike


Title: Re: By Jupiter
Post by: crueby on June 27, 2018, 11:00:56 PM
Thats quite a sophisticated bit of engineering, learning a lot!


 :popcorn: :popcorn: :popcorn:

Title: Re: By Jupiter
Post by: zeeprogrammer on June 28, 2018, 12:09:49 AM
I cannot express enough my  :o

Wow. What engineering and modelling.
Title: Re: By Jupiter
Post by: Admiral_dk on June 28, 2018, 11:22:47 AM
Quote
Miraculously all 12 studs lined up with the holes previously drilled in the Induction Manifold flange.

Oh that is so great when you discover that one of the possible  :Mad:  :cussing:  :Director:  :slap:  did not happen, but all is good phew  :LittleAngel: - great work Mike  :praise2:
Title: Re: By Jupiter
Post by: steamer on July 18, 2018, 11:02:15 AM
Beautiful work Mike!    Nice bit with the manifold flanges!


Dave
Title: Re: By Jupiter
Post by: Ye-Ole Steam Dude on July 18, 2018, 11:40:47 AM
Sure am enjoying and being amazed by your work, thanks for sharing.

Have a great day,
Thomas
Title: Re: By Jupiter
Post by: Vixen on July 18, 2018, 03:38:23 PM
Thanks Guys,

Not much progress to report other than making and fitting the exhaust heater pipe and flanges, which runs from side to side in the Induction Manifold. It's purpose was to heat up the fuel/ air mixture by ducting some of the exhaust gasses through the pipe. This was done to prevent icing at high altitudes.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070213.JPG)

I have been distracted by an extensive modification program on my Emco VMC100 mill. I have been fitting new motors and controllers and new spindle bearings.

Mike

Title: Re: By Jupiter
Post by: steamer on July 18, 2018, 07:36:11 PM
Do keep me informed with the machine upgrade!
Title: Re: By Jupiter
Post by: Tennessee Whiskey on July 18, 2018, 07:37:51 PM
Amazing build Mike  :ThumbsUp: :ThumbsUp:. When I learned to fly in a Cessna 150, there were two controls for cabin heat and carb heat, one sent the heat to the cabin and one sent the heat to the carb for deicing, and they both came from the same source, the exhaust manifold.

Cletus
Title: Re: By Jupiter
Post by: Vixen on July 18, 2018, 08:43:39 PM
When I learned to fly in a Cessna 150, there were two controls for cabin heat and carb heat, one sent the heat to the cabin and one sent the heat to the carb for deicing, and they both came from the same source, the exhaust manifold.
Cletus
Hi Cletus,

Do you still remember the bit about applying the carb heat early, while the engine is running sweetly. If you leave it too late and the engine starts misfiring, due to icing, there will not be enough exhaust heat to get you out of trouble.

Mike
Title: Re: By Jupiter
Post by: Vixen on September 24, 2018, 04:21:11 PM
I got distracted from the Jupiter project by the refurbish / update program on my Austrian EMCO VMC 100 milling machine. Have a look at  the 'It's as simple as ABC or XYZ' thread for the details. When the VMC was working to my satisfaction I was able to sell on 'Old Faithful', my first CNC mill bought some 20 years ago and used on most days since. It built quite a number of engines. I was sorry to see 'Old Faithful' go, but it's VMC 100 replacement is tighter and more capable in all ways. The departure of the old machine made some much needed bench space (for a few days).

Back to the Jupiter build.

The MK VIIIF version of the Jupiter was launched in 1929, it produced 460 hp (340 kW), a powerful engine for it's day. It was the first Bristol engine to use the new forged cylinder heads and a reduction gearbox to drive larger, more efficient propellers. In 1929, aircraft were not yet flying high enough to need a supercharger to boost the power at altitude. Instead, Roy Fedden, Bristol's chief engineer, devised an over- elaborate Induction Spiral to evenly distribute the fuel mixture from the three barrel carburetor to the nine cylinders. The Induction Spiral was a fixed, light alloy casting which directed the flow in a continuously moving spiral from a carb barrel to three of the nine cylinders. It was an impressive feat of pattern making and precision casting and represents a major challenge to reproduce in model scale. It must have been equally daunting in full size.

I briefly considered more lost wax casting. But the overall cost of pattern making, wax mould making and foundry work was prohibitive. A close friend of mine came to the rescue, he produce a Solidworks 3D model of the spiral and made a test sample in extruded filament 3D print using PLA. You may have seen a photo of the first spiral in a previous posting. The first attempt was pretty close but needed some detail changes to the shape and a change in material to withstand contact with gasoline fuel.



(http://lister-engine.com/coppermine/albums/userpics/10013/Induction__spiral_4.JPG)

This is a view of the 3D model showing the Induction Spiral together with the nine cylinder ports and the three carbutter ports. See how intricately the spiral edges twist between the ports.

We selected a nylon material for it's ability to withstand gasoline contamination while producing a tough, rigid but semi flexible material. The second Induction Spiral with the design changes was printed at Amsterdam University using Selected Laser Sintering (SLS) with PA11 nylon powder. The result was a high quality precision 3D print with fine surface texture and excellent mechanical and chemical compatibility properties.


(http://lister-engine.com/coppermine/albums/userpics/10013/thumbnail_20180918_132322.jpg)

This is the Laser Sintered nylon powder print. The print still requires some handwork with coarse wet  n dry abrasive paper to smooth the surface texture and to achieve a perfect fit into the crankcase.
I used a smear of olive oil instead of Engineers Blue to locate the points of contact between the Spiral and crankcase. I hate the mess of Engineers Blue.
The wall thickness the Spiral are between 1.0 and 1.5mm



(http://lister-engine.com/coppermine/albums/userpics/10013/P1070238.JPG)

The Induction Spiral fits so neatly inside the rear of the crankcase



(http://lister-engine.com/coppermine/albums/userpics/10013/P1070243.JPG)

This is how the Spiral feeds fuel mixture to one of the cylinders



(http://lister-engine.com/coppermine/albums/userpics/10013/P1070241.JPG)

Looking into the carburettor port



(http://lister-engine.com/coppermine/albums/userpics/10013/P1070242.JPG)

The rear cover, inlet manifold and the central accessories gearbox in place.
The numbers cast on the back of the Induction Manifold are there to tell the maintenance engineer which cylinders relate to which carburetter barrel.  285    396    417

Stay tuned

Mike

Title: Re: By Jupiter
Post by: Admiral_dk on September 24, 2018, 09:46:42 PM
The last picture is almost a piece of art Mike  :praise2:

Glad to see you back on this build  :popcorn:
Title: Re: By Jupiter
Post by: crueby on September 24, 2018, 11:15:12 PM
Very impressive parts!
 :popcorn: :popcorn: :popcorn:
Title: Re: By Jupiter
Post by: steamer on September 24, 2018, 11:16:58 PM
That is sooooooo awesome Mike....thanks for sharing that!

Dave
Title: Re: By Jupiter
Post by: crueby on September 24, 2018, 11:38:57 PM
It must have been an interesting conversation between Roy Fedden and the guy who had to carve the master for making the mold for that spiral!
Title: Re: By Jupiter
Post by: steamer on September 24, 2018, 11:54:17 PM
It must have been an interesting conversation between Roy Fedden and the guy who had to carve the master for making the mold for that spiral!

I think that's a printed part crueby.


Title: Re: By Jupiter
Post by: crueby on September 24, 2018, 11:55:59 PM
It must have been an interesting conversation between Roy Fedden and the guy who had to carve the master for making the mold for that spiral!

I think that's a printed part crueby.
I know - I was talking about when Fedden originally designed the part for the engine back in 1929, as Vixen described in his post earlier today. That one had to be a hand made master for casting.
Title: Re: By Jupiter
Post by: Vixen on September 25, 2018, 12:02:07 AM
Hay Crueby,

I think Feddon may have said to the patternmaker "I want it done to MIL TBD 41 standard this time".

For those who are not that familiar with this old fashioned engineering standard; the letters stood for:

Make It Like The Bloody Drawing For Once.

Mike
Title: Re: By Jupiter
Post by: 90LX_Notch on September 25, 2018, 12:06:28 AM
I continue to be blown away by this build. Wow.

-Bob
Title: Re: By Jupiter
Post by: Craig DeShong on September 25, 2018, 01:19:42 AM
And this will be hidden inside the engine for no one to see.  What a shame !
Title: Re: By Jupiter
Post by: crueby on September 25, 2018, 01:28:14 AM
Hay Crueby,

I think Feddon may have said to the patternmaker "I want it done to MIL TBD 41 standard this time".

For those who are not that familiar with this old fashioned engineering standard; the letters stood for:

Make It Like The Bloody Drawing For Once.

Mike


 :ROFL:    Great acronym!
Title: Re: By Jupiter
Post by: Vixen on September 25, 2018, 11:44:10 AM
It must have been an interesting conversation between Roy Fedden and the guy who had to carve the master for making the mold for that spiral!

Good morning Crueby

Your question deserves a better answer than MIL TBD 41

I have been a member of the Bristol Heritage Trust (now part of the Rolls Royce Heritage Trust) for over twenty years. I know the lead conservation engineer very well , we have scoured the drawing archives to discover that no  drawings of the Induction Spirol have survived, assuming they ever existed. We did discover some layout diagrams (not engineering drawings) which set out the key dimensions and the locations of the cylinder pipes and inlet manifold etc. I reproduced them in model scale. It soon became obvious that the fluid flowing organic three dimensional shape of the Spiral could not be meaningfully represented on a 2D drawing.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070244.JPG)


Not one of that generation of brilliant engineers who designed and crafted the Jupiter are alive today to tell us how they did it. we can only guess. Today we can create a 3D model using the latest edition of Solidworks. 3D modeling did not exist for another 80 years after the original design work. The lateral cross section through the Spiral (three thin plates which subdivide the space into three equal areas) can be extruded as a toroid (donut) of the correct diameter, while 9 compete twists were applied. 

Given the difficulty in representing the 3D shape of the Spiral in a 2D drawing. one suspects the pattern maker was only ever given the simple layout diagram and a full size crankcase casting covered with chalk marks to show what was required and told to get on with it; make something that fits!!!!. Actually, the Spiral's shape repeats itself nine times, once for each cylinder. So a full pattern may not have been needed. This could also give a clue to how the mould for the aluminium casting was created. My guess was they fitted together nine identical sectors (like the slices of a cake) to form the mould. I also suspect that the raw casting required a considerable amount of hand finishing before it could be fitted to the engine.

There must have been an easier way to connect the carburettors to the cylinders, but Roy Feddon always got things done his way.

Mike
Title: Re: By Jupiter
Post by: Ye-Ole Steam Dude on September 25, 2018, 12:07:50 PM
Hello Mike,

Thanks for this complete explanation for the original idea/drawing.

It is hard enough to understand today with the 3D drawings and a completed part, but it seems almost impossible how they were able to produce it "back then". I so admire the creators and builders of yesteryear.

Have a great day,
Thomas
Title: Re: By Jupiter
Post by: steamer on September 25, 2018, 12:11:48 PM
I spent a few minutes thinking about doing that drawing on the board....and got no where...... :lolb:

Yup!    "Just Make it!!!"

Dave
Title: Re: By Jupiter
Post by: Jo on September 25, 2018, 12:32:23 PM
8) Looking forward to seeing your progress on this at the Midlands show Mike.

I wonder if they made the original pattern by taking a piece of flat stock and twisting it into a spiral and then bending it into a circle  :noidea: Or you could extrude it like a piece of fusilli pasta..

Jo
Title: Re: By Jupiter
Post by: Jasonb on September 25, 2018, 12:43:56 PM
Probably a turned wooden donut, step out 9 points at various positions around it and then join the dots to draw a spiral followed by some carving gouges.

The making in segments would have been a possibility, I saw a post where a large final drive gear for a traction engine was cast from a series of cores consisting of about 4 teeth each laid into the mould.

It's looking good though Mike, was there any reason you went with a sintered plastic over a sintered metal?
Title: Re: By Jupiter
Post by: Jo on September 25, 2018, 12:51:23 PM
We only have a small table at the Midlands show, so we are having to time share to give each other some space.. I will only be doing Friday and the Saturday What day(s) are you planning to be there?

:( I am going Thursday as I am picking up two little flywheels from Chipmaster for Eric who is planning to visit on Friday.

So the only way I might get to see the Jupiter before Guildford would be to visit your in the Minx (https://www.cheesebuerger.de/images/smilie/verschiedene/e040.gif)

Jo
Title: Re: By Jupiter
Post by: Jasonb on September 25, 2018, 01:14:39 PM
I've seen photos from Wilton before and you do seem to get some nice models there, Jo did you have to give back your NBC suit when you retired?
Title: Re: By Jupiter
Post by: Jo on September 25, 2018, 02:14:21 PM
Thanks for that Mike. I just checked and it is a different Wilton I thought it was the one with the rather nice windmill over by the Kennet and Avon near the Crofton Beam engines so I have added that one to the list. Looks like I have a show to go to every other month now  8)

I've seen photos from Wilton before and you do seem to get some nice models there, Jo did you have to give back your NBC suit when you retired?

I didn't bother with one I am happily living within the complete destruction range of the anticipated local hypocentre so I am looking forward to being vaporised :ThumbsUp:

Jo
Title: Re: By Jupiter
Post by: Jo on September 25, 2018, 03:55:23 PM
I have just tried posting the Wilton Show on the Calendar but it does not seem to have shown up  :headscratch:

My list is: Alley Palley (Jan), Wilton (March), Guildford (July), Bristol (Aug), Midlands (Oct). It used to have the ME show but that was abandoned  :wallbang: and Doncaster is too far.

For traction engine enthusiasts the Southern Counties Model Traction Engine group is very good to drop in on, they are having their next steam up on the 13th October with a presentation on 24th November on ‘Ericsson’ and hot air stirling cycle engines which I am hoping to take my Robinson along to  8)

Jo
Title: Re: By Jupiter
Post by: Vixen on October 02, 2018, 02:45:30 PM
I took a few weeks off, to complete the modernisation of my Emco VMC 100 mill and to sell-on my older Emco F1 mill. I also used this as an opportunity to rearrange the workshop. Bad move, now I cannot find anything.

Now I can get back to the Jupiter build and the twin Magnetos which mount at the rear of the engine.

Both main housing are now complete, other than installing the ball race bearings. These are open bearings, without shields or seals, so I will wait until all the machining and fettling is complete before I fit them prior to the assemble the magnetos. Next, I machined both coil covers from billet aluminium. The British Thompson Huston (BTH) name plate was engraved with a 0.2mm (5 thou) engraving point spinning at 6,000 RPM on the upgraded Emco VMC100 Mill. It was a good workout for my 'newest' Mill. You can see I have added all the necessary internal details, which will allow me to add the HT generation coil at a later stage. For now, I am initially, only intending to use the two magnetos as ignition distributors using an external spark coil. The parts to make a full working magneto, can be added later, once the engine has run.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070256.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070255.JPG)


The two Distributer Gearbox Housings were the next items to be made, again machined from a solid billet. This gearbox contains the 2:2.25 reduction gears which turn the rotor arm at the required speed. I had hoped to use a 0.6Module involute cutter to cut these gears, but as has been related elsewhere, these cutters have gone walkabout on their way to me from China, so I will need to make some single point gear cutters instead.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070253.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070257.JPG)

In this final photo you can see the two, nine cylinder distributor caps, which were machined from Delrin. The caps are not quite finished, I still need to make and install the nine brass contacts for the plug leads. You will notice the interesting star shape on the inside of the distributor cap. This feature was used, on the full size engines, to maximise the surface area (distance) between plug leads in order to prevent arcing or flashover between adjacent leads due to condensation or the effects of altitude.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070252.JPG)

There's lots more magneto stuff to follow. that can wait until the next update

Stay tuned

Mike


Title: Re: By Jupiter
Post by: Zephyrin on October 02, 2018, 03:08:23 PM
I learn a lot reading all that stuffs, wow, this spiral is a masterpiece.
Thanks to share all these pictures and studies
Title: Re: By Jupiter
Post by: Vixen on October 02, 2018, 03:13:38 PM
Vous êtes les bienvenus

Mike
Title: Re: By Jupiter
Post by: crueby on October 02, 2018, 03:21:15 PM
Absolutely stunning parts!
Title: Re: By Jupiter
Post by: Jasonb on October 02, 2018, 03:25:23 PM
When you can find such fabulous parts hiding in a bit of billet there really is little point in going looking for castings. :)
Title: Re: By Jupiter
Post by: Roger B on October 02, 2018, 05:10:40 PM
Splendid  :praise2:  :praise2: That's an interesting design feature in the distributor cap  :ThumbsUp:  :ThumbsUp:
Title: Re: By Jupiter
Post by: Jo on October 02, 2018, 05:20:04 PM
 8)

When you can find such fabulous parts hiding in a bit of billet there really is little point in going looking for castings. :)

You need to buy a CNC mill first to help you find it  ::)


Sorry Mike with all that lovely sunshine you nearly had a couple of visitors yesterday but that was before life had other plans  :( And to think I had this strange idea that once I retired I would have more time to do things  :noidea:

Jo
Title: Re: By Jupiter
Post by: Ye-Ole Steam Dude on October 02, 2018, 05:27:45 PM
Just beautiful.

Have a great day,
Thomas
Title: Re: By Jupiter
Post by: crueby on October 02, 2018, 05:31:02 PM
On the picture of the distributor cap, it looks like the two lower contact positions are spaced differently than the rest - is that just where the wires connect, or are the contacts actually farther apart there? If so, why?  :headscratch:
Title: Re: By Jupiter
Post by: Vixen on October 02, 2018, 05:35:29 PM

Sorry Mike with all that lovely sunshine you nearly had a couple of visitors yesterday but that was before life had other plans  :( And to think I had this strange idea that once I retired I would have more time to do things  :noidea:

Jo

Ha ha , If you had turned up yesterday you would have been disappointed, we we out all day. Always best to send a message ahead.

As for retirement, you can take longer and longer doing less an less until eventually you..........................................
Title: Re: By Jupiter
Post by: Dave Otto on October 02, 2018, 05:36:56 PM
Beautiful work Mike, you have been busy.


Dave
Title: Re: By Jupiter
Post by: Vixen on October 02, 2018, 05:40:59 PM
Hi Chris

Well spotted. That scalloped cutout in the bottom of the distributor cap is to clear the contact breaker points cover. The bottom two plug leads are displaced outwards to give clearance. The corresponding two brass pick-ups inside the dizzy cap are slightly longer.

Edit: just found this photo, it is an X ray through a full size dizzy cap showing the longer brass pick-ups

(http://lister-engine.com/coppermine/albums/userpics/10013/image_226576~0.jpg)

Mike
Title: Re: By Jupiter
Post by: crueby on October 02, 2018, 07:06:10 PM
Very slick! Looks a lot like the passages we used to route ink to each head in the printers I worked on. Thanks!
Title: Re: By Jupiter
Post by: Vixen on October 03, 2018, 10:53:40 AM
Hi Chris,

Just noticed, that's an X-ray of a 12 cylinder BTH distributor not a 9 cylinder, but the concept is still the same.

Mike
Title: Re: By Jupiter
Post by: Vixen on October 04, 2018, 01:10:21 PM
This is a cross section through a full size BTH SC9 nine cylinder magneto. There were two of these mounted at the rear of the Bristol Jupiter engine. I am basing my design as closely as I can on this drawing. Initially, I will not have the spark generating coil and magnetic rotor, instead I will have a plain shaft and will use the magneto only as a nine cylinder distributor. The other change will be to replace the contact breaker points with a magnetic Hall sensor. I will endeavour to keep everything else as faithful to the full size unit as possible

(http://lister-engine.com/coppermine/albums/userpics/10013/BTH_magneto-2.JPG)


Having just finished the main components, some of the smaller internal parts have been made made. Here you can see the two bearing housings for the distributor shafts together with the ignition timing plate with it's cover dome. 

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070254.JPG)

I am undecided as to which way I am going to trigger the Hall sensor.
Option 1, is to fix a single magnet to the protrusion on the ignition timing plate with a rotating steel chopper plate interrupting the magnetic field between the fixed magnet and the Hall sensor which will be mounted on the inside of the cover dome.
Option 2, is to put the four magnets on a rotating disc, again with the Hall sensor mounted in the cover dome, You can see that I have already prepared a mounting for the Hall sensor inside the dome.

I will build both options and experiment to see which works best.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070249.JPG)


The ignition timing unit is a self contained unit which fits neatly just under the distributor cap. The position of timing unit can be rotated through an angle of 20 degrees in order to advance or retard the ignition timing. This was done manually by the pilot from the cockpit to meet the in flight demands of the engine.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070250.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070251.JPG)

Stay tuned

Mike


Title: Re: By Jupiter
Post by: Jasonb on October 04, 2018, 01:20:05 PM
I can see the dishing of the larger gear that you talked about quite well in that drawing. Will you cut the teeth first and then shape or do the turning before mounting on an arbor to cut the teeth? Though the hole looks to be something other than round :headscratch:
Title: Re: By Jupiter
Post by: Vixen on October 04, 2018, 01:37:29 PM
The plan is to mount the big delrin gear onto the hollow bearing shaft. Then turn the complete  dished profile of the blank, and mill the through holes before cutting the teeth. The teeth will be cut into the blank while it is mounted on the hollow bearing shaft in an attempt to achieve good concentricity.

The curved thingy in the dished gear is the earth connection for the safety spark gap. The safety spark gap was intended to protect the ignition coil from overvoltage which would otherwise put the coils insulation at risk.

Mike
Title: Re: By Jupiter
Post by: Admiral_dk on October 04, 2018, 04:54:13 PM
Mike is the "dummy ignition" (you have two and put distributer and sensor in one) big enough to hold the coil inside ..?..
What I'm asking is how much of the external parts of the ignition system you can hide inside the engine  :thinking:
Title: Re: By Jupiter
Post by: Vixen on October 04, 2018, 06:30:33 PM
Per,

That is a very interesting suggestion.

The two miniature magnetos are quite big at 1/3 scale, so it may be possible to hide a standard electrical ignition coil in place of the magnet ignition coil. It may be more of a problem to hide the TIM electronics PCB. A good sized battery would be too big to include, so would need to be external to the magnetos.

I hope to attempt to recreate 'real' working magnetos later, but only after I get the engine to run. To do that now, would introduce too many additional unknowns.

If you look at the cross section drawing, you will see the rotor arm receives sparks from two different sources. Either from the magneto coil on the left or from the center connection on the distributor cap on the right. The engine mounted magnetos have difficulty in producing sparks at very low speed while attempting to start the engine. so they installed an additional hand cranked magneto in the cockpit The starter magneto fed a continuous stream of untimed sparks to the central lead of the distributor cap. The pilot was very busy during engine start, he was expected to operate the fuel primer pump, crank the start magneo, while juggling with the throttle and ignition advance levers. When the engine started it would turn fast enough to generate it's own sparks and the pilot could rest.

My idea was to feed correctly timed sparks from two external ignition coils to the central lead on each distributor cap, in a similar manner to the hand cranked starter magneto. I could hide the two ignition coils, the TIM electronics PCBs and the battery in a separate box on the running stand. The result will be similar to the original concept.

Mike
Title: Re: By Jupiter
Post by: Admiral_dk on October 04, 2018, 09:49:42 PM
Quote
If you look at the cross section drawing, you will see the rotor arm receives sparks from two different sources.

Ah - that explains another thing that made me wonder when I looked at it first time  - thank you Mike and getting it to run first, before attempting a real magneto really sounds like a solid plan  :ThumbsUp:

 :cheers:   :popcorn:
Title: Re: By Jupiter
Post by: Roger B on October 05, 2018, 07:43:15 PM
The pilot was very busy during engine start, he was expected to operate the fuel primer pump, crank the start magneo, while juggling with the throttle and ignition advance levers. When the engine started it would turn fast enough to generate it's own sparks and the pilot could rest.

Reminds me of my first fuel injection trials  :)

Scale magnetos are always an interesting problem to get enough stored magnetic field to give sufficient spark energy. The fuel chemistry does not scale (as I am finding with the diesel  ::) )
Title: Re: By Jupiter
Post by: Vixen on October 05, 2018, 08:56:32 PM
Hello Roger,

I am sure magnetos and fuel injection are the invention of the devil himself. An invention, whose sole purpose is to torment any model engineer who dares to try to understand their workings and inner secrets. You can get tantalisingly close but there is always another hurdle before you get the cigar.

Keep trying

Mike
Title: Re: By Jupiter
Post by: Art K on October 06, 2018, 03:10:07 AM
Ah, but what kind of cigar? It may make a difference.
Art
Title: Re: By Jupiter
Post by: MMan on October 06, 2018, 07:22:46 AM
A bit off topic but : I have never really understood magnetos and this thread made me go look into them. I found the link below that made it all clear to me:

http://www.wikkeltechniek.nl/image/lucas%20pdf/5.pdf

My gap in understanding was realizing that there was both a contact breaker and a rapid magnetic field change.

Posted in case it helps anyone else.

Martin.
Title: Re: By Jupiter
Post by: Vixen on October 16, 2018, 06:37:21 PM
During the last few weeks, I have been making good progress with the two dummy magnetos for the Jupiter engine.

The exterior of the two magnetos is almost complete as you can see in the next photo. The tiny 8BA wingnuts which secure the ignition points cover, were interesting to make due to their small size and also because any means of holding them quickly disappeared. The final cuts were made with a single 8BA (2.2mm) clamping screw.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070260.JPG)


The input shaft and coupling were next items to be made, together with the 28 tooth gear blank. These items are all keyed to the central shaft

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070248.JPG)


Most of this work was done using my 4th axis unit. As you can see, I have built the 4th axis unit from a redundant EMCO Compact 5 lathe. The spindle motor was replaced with a powerful stepper motor with a 3.6:1 toothed belt drive. I use the 4th axis unit mostly as a horizontal dividing head for gear cutting etc. The spindle can be positioned precisely at any angular division using the stepper motor, no need for a dividing plate. This will be very useful when I cut the 63 tooth gears in the distributor drive as 63 hole dividing plates are not exactly common.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070245.JPG)


Using an redundant lathe as the basis for the 4th axis unit has the advantage of being able to accept my existing three jaw, four jaw or collet chucks, as well as the ability to hold long shafts between centers. I also have a fixed steady available to provide additional support for very long whippy shafts

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070246.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070247.JPG)


For vertical workholding, I like to hold small round items like this distributer spindle in an ER25 collet. The ER25 collet is in a Stevenson block held in a small machine vice.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070258.JPG)


The four mounting holes in each distributor spindle are coordinate drilled and tapped 8BA. The 63 tooth gear blank is then coordinate drilled in the same setting to ensure everything is concentric. The gear blank is then bolted in place so that the three kidney shaped holes can be machined, all at the same setting

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070259.JPG)


Here is the distributor 63 tooth gear blank, sitting in place in the heart of the Magneto. I ordered some 0.6 MOD involute cutter from Aliexpress in China but they failed to arrive, I eventually got a full refund. I propose to make some single point cutters from hardened gauge plate following the advise from other forum members. A single point cutter should be adequate as the 63 tooth gear is made from delrin and the 28 tooth gear is made from some soft, free cutting mild steel (EN 1). Neither material should make huge demands on my home made involute cutters.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070261.JPG)


The final photo show some of the collection of parts made for the two magnetos. I often make a few extra pieces so I can select the better ones for the engine and to allow for unexpected disasters, which may be lurking just around the next corner.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070262.JPG)

Stay tuned

Mike


Title: Re: By Jupiter
Post by: Ye-Ole Steam Dude on October 16, 2018, 07:54:05 PM
Hello Mike,

Those mags are too beautiful to be called dummies, how about decorations or accessories ?

Have a great day,
Thomas
Title: Re: By Jupiter
Post by: fumopuc on October 16, 2018, 08:03:34 PM
Hi Mike, brilliant as ever.
Title: Re: By Jupiter
Post by: Vixen on October 16, 2018, 08:14:35 PM
Hello Mike,

Those mags are too beautiful to be called dummies, how about decorations or accessories ?

Have a great day,
Thomas

Thomas, they are only dummies in the sense that the magneto coil part does not generate the sparks. The other parts of the  magnetos will still be earning their keep, acting as the working 9 cylinder distributor. I am also using a magnetic Hall sensor inside the magneto, in place of the contact breaker points, to trigger an external 12 volt spark coil. I have actually made provision in the design for a working magneto coil to be added at a later date.

Mike
Title: Re: By Jupiter
Post by: Art K on October 17, 2018, 02:30:15 AM
Mike,
This all looks great. They are only dummies in regard to magnetos, I love the idea of hiding a modern CDI ignition with a hall sensor inside. It only makes it better if you can put the coil inside as well.
Art
Title: Re: By Jupiter
Post by: michelko on October 25, 2018, 09:43:32 AM
What a great looking work  :whoohoo:
Will follow this thread for sure

Michael
Title: Re: By Jupiter
Post by: steamer on October 25, 2018, 10:22:26 AM
Noce work Mike!.   Gage plate cutters work fi e, but with steel, consider gashing the spaces first as it really lightens the load on the gear cutter.    That worked well for me.

Dave
Title: Re: By Jupiter
Post by: Vixen on November 02, 2018, 09:09:43 PM
It's time to do some gear cutting for the Jupiter's two magnetos.

Some of you will recall from my topic "0.6 Module Involute Cutters" www.modelenginemaker.com/index.php/topic,8489.msg184641.html#msg184641  the Jupiter distributer rotor arm is driven via a pair of tiny 63T and 28T gears giving an overall reduction of 2.25:1. The only affordable source of the 0.6 Module involute cutters I could find, was Aliexpress in China. Unfortunately the cutters became lost in transit. I did eventually get a refund but that is no substitute for actual hardware.

Jason gave me good advise and the inspiration to consider making a pair of single point cutters, adequate for the small number of gears required. Zephyrin provided the necessary cutter theory and geometry. Ivan Law's excellent book "Gears and Gear Cutting" provided very practical advice and the "how to"

Following Ivan Law's two buttons method, The 63t gear cutter can be formed by two circular cuts, each of 12.93mm diameter and the 28t pinion cutter by two circular cuts of 5.74mm. It's not quite watchmaking but smaller than clockmaking.

Silver steel 'drill rod' is normally round, so I chose to make the single point cutters from flat gauge plate. Make sure you specify the gauge plate is delivered in the soft 'annealed' condition, otherwise it will be too hard to work, except with a grinder. The circular cuts were made with a 5.0mm end mill with the annealed gauge plate blank held in the machine vice at a slight angle to provide some cutter relief. I machined a single point cutter on each end of the gauge plate blank. The cutters were hardened by quenching in water from cherry red, followed by tempering, to reduce brittleness.


Here is one of the single point cutters mounted in a suitable radial tool holder.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070263.JPG)


The single point cutter was mounted on the vertical spindle of my Emco F1 mill. The gear blank was mounted in the horizontal axis of my 4th axis indexing head. Each tooth was cut in a single pass with the indexing head advanceing by one tooth after each pass. The tooth depth for 0.6 module is only 0.053" (53 thou), it was hardly necessary to gash the spaces beforehand to lighten the load on the single gear cutter. Besides I do not have a suitable small, thin slitting saw available.

I have created a generic G-code listing (LinuxCNC), which can be used for any tooth count or cutter size. Here is my code for 63T 0.6 mod. You simply enter the gear tooth count and tooth depth and other parameters in the appropriate # pidgeon holes . The program does the angular division and tool paths, by looping around until the specified number of teeth have been cut. You are all welcome to use this code if you wish.

#1=63(number of teeth)
 #2=[360/#1](tooth increment angle)
 #3=-.1(y clearance)
 #4=0.2(X start of tooth)
 #5=-.01(X end of tooth)
 #6=0(starting A axis position)
 #7=2(x and y feed rate)
 #8=0.053(depth of cut 2.25 x 0.6 mod)
 G0 X#4 Y#3
 G0 Z0
 G0 A#6
 M3 S200 M8
 o200 do
   G1 Y#8 F#7
   G1 X#5
   G0 Y#3
   G0 X#4
   #6=[#6+#2]
   G0 A#6
 o200 while[#6 lt 359.9]
 M30

Here is the setup on my Emco F1 Mill. The tapered ER25 closure nuts, made by Emco, are a distinct advantage when gear cutting these small gears. They allow you get get right in close and reduce overhang etc.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070267.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070265.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070266.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070268.JPG)


Here you see the results of about three hours of gear cutting. Four nice, deeply dished, delrin gears for the magneto, 63 teeth, 0.6 module, about 1.5 inch (40mm) diameter, waiting for the steel 28T pinions to be cut.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070269.JPG)

Stay tuned,

Mike

Title: Re: By Jupiter
Post by: Ye-Ole Steam Dude on November 02, 2018, 09:18:13 PM
Hello Mike,

That is some neat stuff. The gears look great.

Have a great day,
Thomas
Title: Re: By Jupiter
Post by: kvom on November 03, 2018, 12:10:20 AM
What feedrate did you use, and how did you calculate it?
Title: Re: By Jupiter
Post by: Jasonb on November 03, 2018, 07:20:30 AM
Mike, when you tilted the tool blank at an angle did you compensate by cutting an eliptical shape as cutting a circle only produces the correct profile when the bit is horizontal otherwise you get too long a cutter profile.
Title: Re: By Jupiter
Post by: Vixen on November 03, 2018, 09:32:40 AM
Kvom,

The feed rates are programmed in parameter #7 of my G-code program. In the example shown, I set the feed rate arbitrarily at 2.0 inches per minute. In practice, for the first gear, I throttled the feed rate back to a cautious 1 inch per minute, using the feed rate slider. I wanted the single tooth cutter to survive all four gear wheels, some 250 teeth, so decided to keep the cutter loading extremely low. The tool cutting diameter was a little over 1 inch and the spindle speed 2000 RPM, feed rate 1 inch per minute. I know I could have increased the feed rate considerable, but 15 seconds per tooth did not seem unreasonable. Time is no longer money, when you have retired.

Jason,

Quite correct, a circle becomes slightly elliptical on an inclined plane. But remember the perfect gear flank shape is actually an involute curve, so a circle is only an approximation. An ellipse is actually a slightly better approximation. However, as we discussed in the other topic, the tooth face is only a very small part of the cutting (or button) circle and you have quite a bit out of latitude with the circle diameter before it makes any measurable difference to the tooth profile, especially with a gear as small as 0.6 module. To illustrate the point, the #2 cutter from a standard set of 8 is capable of producing perfectly adequate gears over the range 55T to 134T. My single point cutter was designed and machined specifically for 63T geometry. I'm happy.

Mike
Title: Re: By Jupiter
Post by: steamer on November 03, 2018, 12:22:34 PM
Looks good Mike!   I did something quite similar, using the same references, only the button worked out to a 5/32 end mill diameter, so I made the cutter using the end mill instead of making the buttons.

It worked quite well.   It's a little tougher going in steel....gashing them first with a saw worked very well in steel

Dave
Title: Re: By Jupiter
Post by: steamer on November 03, 2018, 12:34:48 PM
A couple of shots of what I meant
Title: Re: By Jupiter
Post by: Vixen on November 03, 2018, 12:44:14 PM
Hello Dave,

Yes, we all walk the same paths. Good looking gears.

Actually the profile of the cutter is probably a second order issue. You can get far bigger and measurable errors if you are a thou or two out when setting the cutter centre height or the outside diameter or PCD. I could probably be in trouble with those fractional inch sizes.

One of the biggest sources of error can be getting lost with the vernier wheel on a dividing head. Then you get to ask yourself "How do you want that last tooth to look? One extra wide tooth or two very thin teeth?"

I'm now looking for a small slitting saw to gash the steel wheels before the involute cutter. Or I could make and use an undersize cutter, that has the advantage of maintaining centre height with the same tool holder.

Mike
Title: Re: By Jupiter
Post by: steamer on November 03, 2018, 02:08:20 PM
Hello Dave,

Yes, we all walk the same paths. Good looking gears.

Actually the profile of the cutter is probably a second order issue. You can get far bigger and measurable errors if you are a thou or two out when setting the cutter centre height or the outside diameter or PCD. I could probably be in trouble with those fractional inch sizes.

One of the biggest sources of error can be getting lost with the vernier wheel on a dividing head. Then you get to ask yourself "How do you want that last tooth to look? One extra wide tooth or two very thin teeth?"

I'm now looking for a small slitting saw to gash the steel wheels before the involute cutter. Or I could make and use an undersize cutter, that has the advantage of maintaining centre height with the same tool holder.

Mike

Agreed!

Yes the cylindrical approximation of a section of an involute is more than adequate and has been done for many years.     Just watch your cutter speed with tool steel cutters    very unforgiving in steel...
Title: Re: By Jupiter
Post by: kvom on November 03, 2018, 02:51:11 PM
The gashing could be done with a small endmill at Y0.
Title: Re: By Jupiter
Post by: Vixen on November 03, 2018, 04:03:14 PM
The gashing could be done with a small endmill at Y0.

Unfortunately a 28T x 0.6 module tooth gap is very very small, just 0.020" wide at the root and 0.062" at the widest point. The tooth depth is only 0.053". This more or less eliminates any thoughts of gashing with an end mill at Y0.

I have found both a 0.016" and a 0.025" slitting saw (2.73" diameter), which may be worth a try. The 0.016" saw would go to full depth, the 0.025" saw to about 75%.

Cheers

Mike
Title: Re: By Jupiter
Post by: Jasonb on November 03, 2018, 04:09:34 PM
50mm x 0.5mm any good to you?

https://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Slitting-Saws-and-Arbors/HSS-Fine-Tooth-Slitting-Saws-50mm
Title: Re: By Jupiter
Post by: Vixen on November 03, 2018, 04:15:43 PM
50mm x 0.5mm any good to you?


Could be.     0.5mm is almost 0.020".

You seem to know the Arc catalog off by heart, almost as if you worked for them.  :mischief:

Mike
Title: Re: By Jupiter
Post by: Jasonb on November 03, 2018, 05:11:30 PM
Not just the catalog, it seems I have most of their stock :Lol:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/763558.jpg)

I only like to suggest things I have used though it is the 80mm ones I have actually cut stuff with and they seem to work fine, slightly hollow ground too.
Title: Re: By Jupiter
Post by: Vixen on November 03, 2018, 05:26:13 PM
Jason,

Sounds like the SAS motto applies: "He would dies with the most toys....wins"

Yes, all slitting saws need to be hollow ground otherwise they just rub. Always need to remember that when you 'mike' them for thickness.

Thanks for the help and advice

Mike
Title: Re: By Jupiter
Post by: Art K on November 03, 2018, 05:30:56 PM
Mike,
It hardly seems that you would need to use a roughing pass in this application. After all the gear is plastic.
Art
Title: Re: By Jupiter
Post by: Vixen on November 03, 2018, 05:35:52 PM
Hello Art,

The plastic 63T gears are all finished. I am preparing to cut the smaller 28T steel pinions. I only have two single point cutters for 28 Teeth, so I need to do everything possible to make them last.

Mike
Title: Re: By Jupiter
Post by: Vixen on November 04, 2018, 04:52:49 PM
The 28 T steel pinions turned out to be a bit of an anticlimax in the end.

I followed Steamers advice and gashed each tooth space to full depth with a 16 thou wide slitting saw. Then changed over to the 28T single point involute form tool. After resetting the centre height and Y offset, the full set of teeth were formed in no time.

Single point tool diameter 1.0 inch at 950 RPM, depth of cut 53 thou with 2.0 inch per minute feed rate. Time to machine all 28 teeth: just under 5 minutes.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070274.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070275.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070273.JPG)

The two gears fit perfectly into the magneto housing and spin freely.

Jobs a good un'

Stay tuned

Mike

No single point cutters were harmed during the making of these parts.

Title: Re: By Jupiter
Post by: Vixen on November 05, 2018, 12:10:56 PM
One thing I noticed, while I was cutting the magneto gears, was that the sound of the single point cutter was almost identical to that made by a multi tooth involute cutter. A distinct click, click, click, once for every revolution.

Well, that's exactly what you would expect for a single point cutter but it kind of suggests that multi point cutters favour one or perhaps two teeth, even when mounted on a high quality tool holder. Perhaps more teeth would engage if the depth of cut, or the feed rate were higher, but I am only doing small stuff at the moment.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070277.JPG)

Looks like I have far less cutter relief on my single point cutter than they use on commercial ones.

Mike
Title: Re: By Jupiter
Post by: Jasonb on November 05, 2018, 12:21:55 PM
It's a bit like slitting saws you seldom get them cutting evenly. If the chip load exceeds the eccentricity you will get them all cutting at least something and that gear cutter could be fed 16 times faster than the single point one and still give the same tooth load.
Title: Re: By Jupiter
Post by: Vixen on November 05, 2018, 12:29:03 PM
It's probably me being over-cautious and not driving the cutters hard enough.
Title: Re: By Jupiter
Post by: steamer on November 05, 2018, 02:38:50 PM
Anti climatic outcomes are usually welcomed in the shop...just sayin...
Title: Re: By Jupiter
Post by: kvom on November 05, 2018, 07:28:17 PM
I suspect that for the Delrin gears, you didn't need to harden the cutter.
Title: Re: By Jupiter
Post by: Admiral_dk on November 06, 2018, 10:21:42 PM
Quote
No single point cutters were harmed during the making of these parts.
    :ROFL:  thanks Mike.

Nice progress (as usual)  :cheers:
Title: Re: By Jupiter
Post by: Art K on November 07, 2018, 02:59:54 AM
Mike,
The multi point cutters probably run out a bit so there is probably a high point as it spins around.
Art
Title: Re: By Jupiter
Post by: Craig DeShong on November 13, 2018, 01:14:36 AM
Anti climatic outcomes are usually welcomed in the shop...just sayin...

 :ThumbsUp:

Still following Mike, this build continues to amaze.
Title: Re: By Jupiter
Post by: Vixen on November 13, 2018, 12:36:03 PM
The magnetos are nearing completion. In this instalment from Vixen's Den, I will concentrate on ignition trigger circuits. The original BTH magnetos would have had cam operated ignition points. Ignition contact points always demanded constant maintenance and were always potentially unreliable. This unreliability was not something I wanted to copy into 1/3 scale magnetos so I made an early decision to use a magnetic Hall device, rather than contact points as the ignition trigger for my model magnetos. This was a conscious decision and one of the few places where I deviated from the original BTH magneto design and blueprints.

The first photo of the assembly sequence shows the magneto's input coupling. The magneto is surrounded by the components which make up the ignition trigger circuit and the nine cylinder distributor.
(http://lister-engine.com/coppermine/albums/userpics/10013/P1070283.JPG)


The next shows the 63t/28t gears correctly installed inside the magneto's gear housing. They mesh and spin beautifully with little or no backlash.
(http://lister-engine.com/coppermine/albums/userpics/10013/P1070282.JPG)


Here I have added the distributor's rotor arm and the timing plate for the ignition trigger circuit. You can see the single 3mm diameter rear earth magnet bonded into the vertical boss of the timing plate. The timing plate can be moved through about 20 degrees to advance or retard the ignition timing manually. Again this feature is true to the original design, automatic advance / retard had not yet been invented in 1929.
(http://lister-engine.com/coppermine/albums/userpics/10013/P1070281.JPG)


This is the magnetic field chopper blade in position on the input shaft . The field chopper has four blades, each of which will interrupt the magnetic field as seen by the Hall effect pick up device. The position of the field chopper on the input shaft can be set via a single grub screw. The precise triggering position is indicated by the  LED  light on the TIM-6 ignition module. You can see another four blade field chopper more clearly, on the table below the magneto.
(http://lister-engine.com/coppermine/albums/userpics/10013/P1070280.JPG)


The Hall effect pickup sensor is bonded in place, inside the contact breaker's domed cover. It rotates together with the magnet on the timing pate, as the advance/ retard position is adjusted. The contact breaker cover in the photo has been modified for test purposes, the open end allows me see the position and clearances of everything inside.
(http://lister-engine.com/coppermine/albums/userpics/10013/P1070279.JPG)


The final photo of this series shows the full assembled magneto. In the foreground from left to right are 1) a distributor rotor arm, 2) a four blade magnetic field chopper, 3) an unmachined field chopper which can be cut to give different 'dwell' times, 4) a four magnet rotor in case the field chopper blades did not work and 5) the Hall sensor bonded into the test contact breaker cover.
(http://lister-engine.com/coppermine/albums/userpics/10013/P1070278.JPG)


I am happy to report that the four blade field chopper appears to work perfectly and I plan to proceed with this design. In the event that the field chopper idea does not quite work out as expected, when I run the engine, I always have the more conventional four magnet rotor as a backup.

To complete the magnetos, I still have to add the brass contacts to the rotor arm and distributor cap, and off course I need to add the ignition lead harness. I will delay the ignition lead harness for as long as possible as they will get in the way during the rest of the build.



Stay tuned

Mike


Title: Re: By Jupiter
Post by: Vixen on December 03, 2018, 11:43:13 AM
Some more Jupiter progress to report from Vixen's den.

Here is the rear cover, which acts as the accessories drive, I've got it mounted on an angle plate. The two magneto mounting flanges needed some extra machining to clear a couple of interference points.

The rear cover was clamped to a small angle plate, which was set over at an angle of 32 degrees. I used a digital spirit level to carefully set each magneto flange perfectly square and parallel with the mill bed, in both x an y axes. I also needed to rotate the set-up to align two of the existing bolt holes parallel to the x axis. After that, it was just a case of tracing the magneto flange outline with a 6mm end mill in small Z axis increments, until all the points of interference disappeared.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070288.JPG)


Here the two magnetos are offered up to the rear cover to check the fit.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070291.JPG)



The rear cover complete with the two magnetos in place on the rear of the mighty Jupiter. 

The rear of the engine is starting to look busy. The cast inlet manifold is at the bottom. The scavenge and pressure oil pumps are in the centre. The two magnetos angled outwards. At the top centre is the mounting flange for the Hand Turning Gear which is used to start the engine with a cranking handle through an enormous gear reduction.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070290.JPG)


It really is getting to look busy as more parts are made and added.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070289.JPG)


These are the bevel gears which drive the two magnetos. The centre bevel gear is driven by the crankshaft, the gears have 36:32 teeth with a 32 degree angle.  The two output bevels drive the magneto input shafts at 1.125 times the crankshaft speed.

(http://lister-engine.com/coppermine/albums/userpics/10013/gearsPC132510.jpg)

There's more to follow, so stay tuned

Title: Re: By Jupiter
Post by: steamer on December 03, 2018, 12:04:48 PM
Sweeeet!


Coming along nicely Mike!

Dave
Title: Re: By Jupiter
Post by: Ye-Ole Steam Dude on December 03, 2018, 01:43:24 PM
Hello Mike,

WOW!

Have a great day,
Thomas
Title: Re: By Jupiter
Post by: Kim on December 03, 2018, 02:54:51 PM
I'll say!  Wow!

That's really looking impressive, Mike!
Kim
Title: Re: By Jupiter
Post by: zeeprogrammer on December 03, 2018, 03:17:47 PM
There's more to follow, so stay tuned

 :ThumbsUp: :popcorn:

It looks awesome!
Title: Re: By Jupiter
Post by: Roger B on December 03, 2018, 03:20:50 PM
Excellent  :praise2:  :praise2: The complete engine looks magnificent  :ThumbsUp:  :ThumbsUp:
Title: Re: By Jupiter
Post by: 10KPete on December 03, 2018, 06:00:20 PM
Wow, that's a beautiful engine!!

 :popcorn:

Pete
Title: Re: By Jupiter
Post by: crueby on December 03, 2018, 09:39:15 PM
Wow, that's a beautiful engine!!

 :popcorn:

Pete
Triple that!   :popcorn: :popcorn: :popcorn:
Title: Re: By Jupiter
Post by: Vixen on December 04, 2018, 09:24:19 AM
Thank you all for dropping in and saying hello.

There seems to be an endless amount of small parts required for a big radial engine. For example; the overhead valve rocker arms are located by two control rods. The idea is to control the valve/ rocker clearance as the cylinder expands when running. A bit of an overkill, but true to the design of the original engine.

Each rocker assembly has 6 pivot pins and each floating pivot pin is retained by a pair of bolts. That requires a total of 108 special, short 8 BA bolts to be made up and fitted. A lot of work and you can hardly notice the difference

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070292.JPG)

That's one more item crossed off the list. I'm getting there.....slowly   :help:





Title: Re: By Jupiter
Post by: Admiral_dk on December 04, 2018, 11:33:07 AM
And we usually think that an engine is more or less made when you have finished the case, crank, conrod(s), piston(s), cylinder(s), valves, camshaft(s) (if any) and a carburator ….. but this build really show how much more goes into the full size ones and models in big size  :o

Fantastic progress Mike.
Title: Re: By Jupiter
Post by: Craig DeShong on December 04, 2018, 06:49:52 PM
The detail on this model is so extraordinary that it's hard to tell if we're looking at the model or the full size.  Just gorgeous!
Title: Re: By Jupiter
Post by: Vixen on December 04, 2018, 08:21:58 PM
Hi Craig,

It's a full size engine, in miniature.     It should be powerful enough to power a hang glider or microlight.

I have also got good documentation, some blueprints from 1929 and there are a small number of surviving Jupiter engines in UK museums. So, I have no excuse.

Mike
Title: Re: By Jupiter
Post by: crueby on December 04, 2018, 09:09:08 PM
Simply stunning work!
 :popcorn: :popcorn: :popcorn:
Title: Re: By Jupiter
Post by: Vixen on December 04, 2018, 09:50:15 PM
My dear friend Dan, in France, deserves most, if not all, of the credit for this beautiful engine. I am only completing what he started, twenty years ago. I struggle to maintain his high standards

Mike
Title: Re: By Jupiter
Post by: Art K on December 05, 2018, 03:22:21 AM
Mike,
From looking at this work of art as it progresses, and I have to disagree.
Quote
I struggle to maintain his high standards
Dan may have started this project but he passed it off to be finished by someone capable of a very high standard of work, you. Keep up the good work.  :headscratch: Are you sure you want to throw the Jupiter in a microlight?
Art
Title: Re: By Jupiter
Post by: Vixen on December 05, 2018, 10:04:42 AM
.  :headscratch: Are you sure you want to throw the Jupiter in a microlight?
Art

Art,

Ha ha, Well it wont be happening any time soon. It would need all sorts of CAA inspections, tests, certifications etc, so I will stick with the trusty old Rotax for now.

Mike  :noidea:
Title: Re: By Jupiter
Post by: fumopuc on December 05, 2018, 10:07:53 AM
Hi Mike,
some holidays and some time to study your postings
The job you have done so far is brilliant and so far away of my skills.
I will enjoy all future steps.
Title: Re: By Jupiter
Post by: Steamer5 on December 06, 2018, 05:52:38 AM
Mike,
 Just caught up....just WOW! Can’t wait for the video

Cheers Kerrin
Title: Re: By Jupiter
Post by: Vixen on December 11, 2018, 04:01:56 PM
Hi, thanks for calling by and saying hello.

This week it was back to the Induction Spiral and Induction Cover.

You may remember that the Induction Spiral is a unique feature of the un-supercharged Bristol Jupiter engines. It's purpose was to ensure an even fuel/ air mixture was delivered to each cylinder from the three barrel carburetor.  The spiral flow helped to prevent fuel droplets from forming and spoiling the fuel / air ratio. The flow from each inlet port was directed in a spiral motion to three of the nine cylinders.

The real Induction Spirol was an intricate aluminium casting. After several unsuccessful attempts, I had the Spiral 3D printed in a nylon material.

(http://lister-engine.com/coppermine/albums/userpics/10013/thumbnail_20180918_132322.jpg)


The raw print needed quite a lot of hand finishing with wet-n-dry abrasive paper to smooth the surface and make it fit the engine casings.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070298.JPG)


Then I turned my attention to adding the finishing touches to the outside of the Induction Spiral Cover. I made these tiny fuel priming bosses on the CNC mill and bonded them to the rear cover. The bolts, which act as fuel jets, also secure the brass banjos of the priming system pipework to the bosses on the rear cover.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070295.JPG)

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070296.JPG)


Here you can see the rear cover in place on the back of the engine. One small job completed, a million more still to be done.

Damn, just dropped the rear cover and bent one of the studs. It should bend straight, with luck.

(http://lister-engine.com/coppermine/albums/userpics/10013/P1070300.JPG)


                                     "Like a circle in a spiral, like a wheel within a wheel,
                                    Never ending or beginning, like an ever spinning reel.
                                                       Let the images unwind,
                                   Like the spirals that you find, in the Jupiter in your Mind"

Mike
Title: Re: By Jupiter
Post by: cnr6400 on December 11, 2018, 10:40:56 PM
Great work Mike, sorry to hear about the bent stud. Hope you have a few spares.

Was the idea of the spiral to get the intake charge rotating fast, like a cyclone dust extractor, to get the heaviest particles to fly outward toward the walls?

If so, where did the drops of fuel end up? I just have a picture in my head of all the drops coalescing into a river of liquid fuel dripping down into the lowest part of the manifold (particularly at idle)  and putting out the fire in the bottom cylinders! I probably don't have the whole concept right, the designers probably sorted it out some clever way.
Title: Re: By Jupiter
Post by: Vixen on December 11, 2018, 11:32:29 PM
I understand the idea of the spiral was to keep the fuel / air fully mixed and moving at a steady pace. The handbook says they introduced the spiral to prevent stagnant air pockets which could rain fuel droplets. Before they introduced the spiral, the bottom cylinders always ran richer than the upper ones. I don't believe the airflow was fast enough for the cyclone dust extractor effect.

By the 1930's the aircraft were then flying high enough to warrant the extra expense and complexity of a supercharger. The centrifugal blower acted like a huge food blender and solved the fuel droplet problem completely.

Mike
Title: Re: By Jupiter
Post by: Vixen on December 15, 2018, 10:02:34 PM
As I have said before, the purpose of the Induction Spiral was ensure even distribution of the fuel air mixture to each of the nine cylinders.

The individual carburetor chokes each fed three cylinders distributed 120 degrees apart. This made sure the product of each carb was evenly represented around the nine cylinders. So that if one carb was supplying a mixture richer or leaner than the others, the discrepancy would be evenly distributed around the engine, preserving, at least, the balance if not fuel efficiency.

Before delivery to the customer, each Bristol Jupiter was run up on the outdoor test stands and everything carefully adjusted. The three carburettor barrels were individually adjusted to achieve the correct running mixture at tickover, cruise power and for maximum take-off power and all points in between. This was done in the test stands, late at night, with open exhausts and full power, for as many hours as needed. The colour and intensity of the exhaust flame gave the test engineers a clear indication of the mixture strength and evenness of distribution.

(http://lister-engine.com/coppermine/albums/userpics/10013/By_Jupiter.jpg)

                                                                      "By Jupiter, what a racket"

The local residents must have been impressed with the thoroughness of the Bristol engineers working late into the night.

Mike
Title: Re: By Jupiter
Post by: Ye-Ole Steam Dude on December 15, 2018, 10:10:30 PM
Hello Mike,

That is a neat photo, I can almost hear the roar.

Have a great day,
Thomas
Title: Re: By Jupiter
Post by: crueby on December 15, 2018, 10:32:28 PM
Fantastic photo!
Title: Re: By Jupiter
Post by: Art K on December 15, 2018, 11:06:57 PM
Mike,
Looks like a lot of work to be sure of proper running. Cool photo. Reminds me of the blip of info about the Brough Superior. Each bike was taken out to the sand flats in Wales and run up to 110 mph guaranteed.
Art
Title: Re: By Jupiter
Post by: steamer on December 16, 2018, 12:06:20 AM
"Listen to the sounds of my people!!!"  :lolb:   I suspect a couple of years in,....it was getting pretty old.

Dave
Title: Re: By Jupiter
Post by: steamer on December 16, 2018, 04:57:22 PM
I for one, am thankful to see this build.   Mike, your work is an inspiration to me.   Watching this build has given me the inspiration to work through my recovery and get on with some of my projects.   Keep it coming!

Dave
Title: Re: By Jupiter
Post by: Vixen on December 16, 2018, 05:23:05 PM
Thanks Dave, I hope the recovery is going well. You have been out for quite some time.

Mike
Title: Re: By Jupiter
Post by: steamer on December 16, 2018, 05:28:30 PM
Thanks Dave, I hope the recovery is going well. You have been out for quite some time.

Mike

Oh I know   its frustrating!...  but its coming along.   And i know i have an even bigger project after!