Author Topic: By Jupiter  (Read 57293 times)

Online Vixen

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Re: By Jupiter
« Reply #60 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
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Offline Myrickman

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Re: By Jupiter
« Reply #61 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.
« Last Edit: February 13, 2018, 10:38:42 PM by Myrickman »

Offline Chipswitheverything

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Re: By Jupiter
« Reply #62 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

Online Vixen

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Re: By Jupiter
« Reply #63 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

It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Online Vixen

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Re: By Jupiter
« Reply #64 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.




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.




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




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.




Mike
« Last Edit: March 06, 2018, 10:34:35 PM by Vixen »
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Online fumopuc

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Re: By Jupiter
« Reply #65 on: February 23, 2018, 07:19:45 PM »
Hi Mike, always a pleasure to follow your projects.
Kind Regards
Achim

Offline zeeprogrammer

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Re: By Jupiter
« Reply #66 on: February 23, 2018, 11:52:08 PM »
All of this is way beyond me but I sure enjoy following along and learning.  :ThumbsUp:
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Online crueby

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Re: By Jupiter
« Reply #67 on: February 24, 2018, 03:29:03 AM »
Wow, that is some impressive sculpting!


 :popcorn: :popcorn:

Online Vixen

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Re: By Jupiter
« Reply #68 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.



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
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Offline petertha

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Re: By Jupiter
« Reply #69 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?

Offline Dave Otto

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Re: By Jupiter
« Reply #70 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

Online Vixen

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Re: By Jupiter
« Reply #71 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.




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.






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.




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.






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

« Last Edit: February 28, 2018, 04:28:58 PM by Vixen »
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Offline Roger B

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Re: By Jupiter
« Reply #72 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  :)
Best regards

Roger

Online MMan

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Re: By Jupiter
« Reply #73 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.

Online Vixen

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Re: By Jupiter
« Reply #74 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
« Last Edit: February 28, 2018, 09:41:05 PM by Vixen »
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.