Model Engine Maker
Engines => From Kits/Castings => Topic started by: RayW on November 12, 2022, 02:44:36 PM
-
Thanks to Graham, I am now the proud owner of a set of castings for his little horizontal flame licker engine Nattie. Well, when I say a set of castings, the flywheels will be coming later once Graham gets them from the foundry.
This is going to be an interesting project as there are no plans or drawings, so it is very much a case of make it up as you go.
To date, there have only been three other Natties, the original owned by Graham, another built by Grahams friend Mike which is now in the USA, and one with Jason.
If I remember correctly, Graham only took 18 years to get his running so that means mine should be going by the time I am 95!!
The name Nattie, incidentally, comes from the fact that the design is loosely based on a National gas engine.
To give some idea of size, the main bed is about 5 1/2" (140mm) long. Overall length with cylinder head will be about 9". Height 3 1/2". Bore will be 1 1/2".
-
Great to see the castings arrived safely Ray. :ThumbsUp:
The project was started some 22/3 years ago, the first castings were done at the Rhuddlan Iron foundry. At the time both Mike and I were tearing our hair out trying to get it to run. Needless to say after a lapse of 18 years I finally found a solution to the problem. The exhaust port just wasn’t enough on the original design.
The engine is based upon an 1890/1900 National gas engine company of Ashton under Line Manchester size N, deep base gas engine. Picture below. A model was going to be used as a raffle prize for an event at the Anson engine museum but, for obvious reasons it never happened.
:cheers: Graham.
-
Good to see the Nattie family growing Ray. Mine has been sitting idle for a while as other things have taken my fancy, it just needs the shutter and cam doing to complete it. Let me know if you want me to measure anything as it's easy enough to pull it apart.
Although I have not yet done a write up this link should take you to my album though it seems I've not taken images of all the parts.
https://app.photobucket.com/u/jasonballamy/a/971abc43-8065-4499-ac0f-7f8320299ed1
-
Thanks Jason, much appreciated. I will no doubt be in touch for info as I make progress. I have tried to open your Photobucket link but there seems to be a problem as it won't open for me.
-
Try it now Ray, I had it set as private.
https://app.photobucket.com/u/jasonballamy/a/971abc43-8065-4499-ac0f-7f8320299ed1
-
Thanks Jason, now opened OK. That will be very helpful.
-
Good morning Ray.
The flame port is driven by a sideshaft, just like the original but at a 1:1 ratio. Originally we bought the gears from HPC Ltd but now, thanks to eBay, you can get 4 gears for under the price of one today. Here’s the link….
https://www.ebay.co.uk/itm/403817016419?hash=item5e055eac63:g:cdUAAOSwR-li7NWS&amdata=enc%3AAQAHAAAAoPX7ejvokWzM8n0hb7sT8i%2BseNAqXxTOUf4%2Fob%2BsQOhaklQvbrH51eNpNUT7fs5YxxtdyRLtRakYeaKmzSsVJePDJGzXkxKyXaLYs9JA%2BHBEZOAn36qAG3VBBRz%2FXFzGZIcwaVVvaIFLmrsGHvdSTYuNV9KWdQC1%2B4YyMBBkAHcJRn7SoKpWXMVAdMJgObwkTWaNWPt3HaMjBB7B93T0lAQ%3D%7Ctkp%3ABk9SR9Lxv4uOYQ
If you like I will order them myself as I think another Nattie needs a home at the Anson engine museum. ;) They have a 6 mm bore and that will save many hours of faffing about trying to accurately bore out the 2 mm versions.
:cheers: Graham.
-
Try it now Ray, I had it set as private.
https://app.photobucket.com/u/jasonballamy/a/971abc43-8065-4499-ac0f-7f8320299ed1
Some great pictures there Jason. :ThumbsUp:
It will be interesting to hear the exhaust note from the twin port reed valves. I received some pictures from the foundry of the flywheels cast from your pattern. Attached below.
Your engine number is 104 and Ray’s is 105. Having recently tracked down Mike’s engine which now lives in the USA the family has decided to keep Mike’s preference of number 112.
:cheers: Graham.
-
If you could order gears for me as the same time Graham, that would be very helpful.
Jason, did you use ball races for the main bearings or bronze bushes? I can't quite see from the photos. Also, what was the thinking behind making the bearing surfaces sloping as opposed to horizontal?
Got the outside of the cylinder and the exhaust port face machined today so a bit more progress. Found my new indexable carbide tipped tools struggling a bit to get a decent finish, but ended up with something acceptable after a bit of trial and error..
-
Ball races as suggested by Graham.
The casting is based on the national Gas engine and that has a sloping joint line. It did not cast too well on my example but the oil cup is supposed to be in the middle with the two surfaces for the nuts as shown by the rings. I think Graham just left his solid but I wanted some nuts at least so decided to go the whole hog and make separate caps from something not as hard!
-
Think I will probably follow your example Jason. Glad to hear you found the castings hard- I thought is was just me. Perhaps some nice ornamental brass or bronze caps would look good. Are your bearings just clamped by the bearing caps and did you use one or two per side?
-
Mine is an old original casting, had hoped the new ones would be softer.
I just gave the caps a quick rub on some emery after boring so they nip the bearings in place. One per sid eat the moment but I bought enough for two
-
Made a start on milling the front face of the bed casting, only for the controller to die on the mill. Have ordered a new one which should be here any day now. Fortunately, it is only a fairly cheap Chinese unit so not too costly to replace at about £20.
With the mill out of action, I decided to do whatever I could on the lathe. The cylinder has now been bored (after a few traumas) and the piston turned to a nice sliding fit.
-
I am pleased the controller board for your mill was still available :)
Good progress Ray
Jo
-
Good to see some more progress, what bore did you end up with?
Jo replacement controller should be easy enough to get as the previous one was just a £20 generic e-bay one
-
As Jason says Jo, the controller is a generic e-bay one. When I converted the mill, a Clarke CMD10, from gear drive to belt drive, I had to fit new electronics as the old ones were integral with the gearbox and had become unreliable anyway. I converted to belt drive because the flimsy plastic gears were constantly breaking.
Jason, the piston ended up as 1.508". I have drilled and tapped the end 2BA for the internal gudgeon pin fork as on CHUK 2.
-
The mill is back up and running with its new controller which means that I have been able to get on with milling the main casting.
The front face of the bed casting has now been bored out to accept the cylinder, which is secured in place with two 2BA grub screws. As this is quite a short casting, I was able to hold it vertically in my little mill and use the boring head.
The main bearing faces have also been milled at a 30 degree angle to mimic the angled main bearings on National engines. Next job will be to make two main bearing caps, possibly from brass. These will house two 0.375" outside diameter ball races each side.
-
Nice work :ThumbsUp:
I sit wondering how to hold / clamp the castings in order to ensure that the Crank will run a perfect 90 degrees to the cylinder and the rest :thinking:
Per :popcorn: :cheers:
-
I tend to bolt the frame down to a steel plate that has been squared up. You can then easily clock an edge of the plate with a DTI to get it true and also the plate can be clamped to an angle plate if needed so you have 3 planes that are easily set rather than trying to clock the ast surfaces.
(https://hosting.photobucket.com/images/v156/jasonballamy/20200829_110922.jpg)
(https://hosting.photobucket.com/images/v156/jasonballamy/20200830_114641.jpg)
(https://hosting.photobucket.com/images/v156/jasonballamy/20200830_123524.jpg)
(https://hosting.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/Robinson%20X-Type/.highres/DSC02610_zpsd8qqtqkb.jpg)
-
Hi Per.
I see Jason beat me to it whilst I was having lunch…. :)
At the Alyn workshop which has tooling available for the “ larger “ toys that I play with I use the Denbigh Universal milling machine for line boring etc. The 150 mm capacity deep jawed machine vice will hold almost anything I need to machine. Like Jason I use a DTI to clock the front face and then adjust the swivel base to suit. Using a series of drills, starting with a centre drill the mains are quickly brought to size and finished with a reamer. All the reamers I use have “ known “ accuracy and the robust nature of the machine ensures a perfect result.
:cheers: Graham.
-
If I got this right - you place it on another flat and square (jig-) plate and use that to keep all the rest in the right angles to the previous opperation .... Well that makes much more sense than trying to do that with the casting itself.
Off course it could be easily done if we all have big five axis (quality) CNC's ;D
I will follow with interest :popcorn: :cheers:
Per
-
I have been tackling exactly this problem today. After fitting my nice new brass bearing caps, I set everything up to bore them vertically on my little mill. Unfortunately I have no horizontal boring facility.
As Jason and Graham have said, it is a case of ensuring that everything is set up square in all 3 axes when boring. One cap has bored slightly off centre, but I think this is probably because I didn't fit the caps exactly in line with each other. It is not an issue and won't show anyway when the crankshaft and flywheels are fitted.
Fortunately, my reamer cut an exact size and the bearings are a perfect slide fit. It just needs the underside of the caps being given a light rub on some emery paper so that they nip the bearings tight.
There are two bearings per side as shown in the attached photos. The bearing caps were made in two parts, then silver soldered together.
-
Nattie is coming along nicely Ray. :ThumbsUp:
I guess you’re going to soft solder the little square oil boxes separately?
:cheers: Graham.
-
Drat, I never thought about oil boxes as we are not using oil lubrication for the bearings. As we are not building a scale model of a National N, I may leave them off.
-
As Graham had gone to the trouble to cast the oil boxes I thought I should at least add them back after cutting off his caps. JBWeld did it for me as I'd made the new caps from iron.
(https://hosting.photobucket.com/images/v156/jasonballamy/DSC04626.JPG)
-
As a matter of interest, did the oil boxes have lids? I have scoured the internet for pictures of National N type engines, but can't find any pictures showing clear details of the bearing caps.
-
Drat, I never thought about oil boxes as we are not using oil lubrication for the bearings. As we are not building a scale model of a National N, I may leave them off.
Hi Ray.
I agree, whilst not being a scale model the oil boxes are quite prominent features on National gas engines. This is the reason Why I put them on the bed pattern. I didn’t however go to the trouble of making them removable just simply line bored the casting.
As the crankshaft was going to be made as a composite the polished shafts were pushed through each set of races and the webs secured with 6 BA grub screws. The crankpin then tied up the two sides together.
I think it’s highly unlikely that the oil boxes would be left uncovered as they would, quite easily, get contaminated with the debris from their working environment. But, like you I have been unable to find any detailed pictures available on the internet.
I will ask Geoff at the Anson engine museum for some photos. It would be nice to see a mechanical cylinder lubricator in action too.
:cheers: Graham.
-
I think there is a lid on the one the flywheel pattern was based on, arrowed red
-
Thanks both of you.OK, you have convinced me. There will be oil boxes on mine!
Thought I would tackle a fairly easy job today and machine the crank webs. At least, I thought it would be easy, but the castings are some of the hardest I have ever tackled. I purchased a set of solid carbide end mills for building Nattie, but I have totally destroyed two of them just trying to mill the edges of the webs. Even turning them in the lathe with carbide inserts, some areas cut OK and others just polished.I will persist to see if I can get a decent finish, otherwise I will make new ones from steel.
-
I used steel
-
I think I got one hard one and one not quite so bad. These two were machined using the same tool at the same speed.
-
You could try heating the offending web up to cherry red and then putting it into a bucket of wood ashes to cool overnight. This has worked for a number of chilled castings for me.
-
Thanks for the suggestion. I don't have access to any wood ashes. Would sand serve the same purpose?
-
You could try it. It's not as good an insulator, and especially not good if damp. But bone dry sand might be sufficient. Ideally it should take several hours to cool a small piece of heated metal. The very slow cooling is what takes the hard chill out of cast iron.
If you know someone with a fireplace, they can save you some wood ashes. A bucket of them is handy to have in the shop for slow cooling anything that needs to be annealed.
I haven't tried this myself but it's possible vermiculite would also work, as long as it is bone dry. Worth a try if that is more available for you.
-
Thanks for that advice. I have a neighbour who has a wood burning stove, so may have to speak nicely to him. I think I may give up with these two castings though, and resort to steel as Jason did.
Jason, what stroke length did you manage to get? I was aiming for 2 inches, but for the webs to be long enough to bored at 1 inch centres they would foul on the rounded cutout at the back of the main casting. I suppose I could always lower and widen that a bit to clear the webs, or, alternatively, I could go for a shorter stroke of, say, 1 3/4".
-
Ray, if they are that local just ask if they can put the parts into the woodburner for the night.
40mm stroke on mine, you could probably get a bit more if the exhaust holes were drilled towards the head and flap valves secured nearer the crank.
-
Many thanks Jason. I think I could probably get 45mm or so and that would still give me enough room to shorten the webs sufficiently to clear the bed. Will have a word with my neighbour.
-
A night in the neighbour's wood burning stove seems to have done the trick and softened the hard spots on the webs, so I should be able to clean them up to finished size now without any further problems. In photo 2, the problem web is the one on the right. As you can see, the end which was glass hard now cuts easily with a file.
Thanks to all for the advice.
-
Well the gears arrived today but I fear they might be a tad too big for Nattie?
Glad you managed to anneal the crank webs ok Ray, we all just need the flywheels now….
:cheers: Graham.
-
Just need to double check but I think I went with MOD 0.5 15T which gives a PCD of 10.56mm and they come with a 3mm bore which is ideal for the side shaft.
https://ghw-modellbau.de/Schraubenrad-Stahl-Modul-05
EDIT Yes the 15T MOD 0.5were the ones that I used
-
Thanks for the link Jason. :ThumbsUp:
Upon reflection I should have probably chosen a smaller Modulus, I went with MOD 1. I will try to cut one in half but I think the downside will be that the sideshaft ends up being too low at the cylinder head.
:cheers: Graham.
-
Unfortunately, the annealing of the webs did not prove as successful as first thought. Although a bit easier to machine, the outer ends of the offending web are still pretty hard. When turning the outer radii on the lathe with a carbide tipped tool, it cuts a bit better than before, but still leaves a very shiny surface with a poor finish and some brittle chips to the edge. With a lot of grinding, filing and sanding, I have finally got a reasonably satisfactory finish which I can live with.
There is, however, one final hurdle to oversome, namely drilling and reaming the crank pin holes, then reducing the overall length of the webs to clear the back of the bedplate. The bosses also need milling to length. I know, Graham, that you put the crankpin at the big end of the webs. Was this for a particular reason or should it really be at the small end?
That's really annoying about the gears. Does the centre line of the sideshaft need to be in line with the centre line of the shutter, or could the gate on the end of the shutter be longer?
-
One piece of goods new is that I have received a full refund from the eBay seller for the set of 6 carbide milling cutters, two of which I ruined trying the mill the glass hard crank web. So, I now have four free good ones left which I will try on some less challenging material in the future. Hopefully, I may also be able to touch up the 1/2" one to make it usable.
-
I know, Graham, that you put the crankpin at the big end of the webs. Was this for a particular reason or should it really be at the small end?
That's really annoying about the gears. Does the centre line of the sideshaft need to be in line with the centre line of the shutter, or could the gate on the end of the shutter be longer?
Good morning Ray.
Pleased to read that you got a full refund. :ThumbsUp:
The main reason that the crankpin is running in the effective “ counterbalance “ area was because I had forgotten about the height of the raceway. I was trying to get as much stroke as possible but discovered, upon assembly that I had overdone it. To get it right the crankpin would have been in a half hole situation. Rather than start from scratch I decided to shorten the stroke by drilling the opposite end to get it running. We were, at that time under a little pressure to get the model finished in time for the event at the Anson.
Needless to say Nattie never ran as intended and, as you know was shelved for nearly 18 years. Had we have got a running engine, at the time a new pair of webs would have been fitted.
Regarding the sideshaft I’m not sure how the Scotch yoke would work if the yoke was offset to the slide? Normally they run through the natural centre line. I’d be inclined to suggest that you follow Jason’s link for the 0.5 MOD gears, recently posted. The ones I have bought, two pairs, were cheaper than a single gear! So no real financial loss.
:cheers: Graham.
-
Now I understand Graham. I am making a fully silver soldered crankshaft and will fit either a bronze or brass big end. I am placing the crank pin in the conventional location opposite the counterweights.
Please let me know how much I owe you for the gears as one of the sets you ordered was for me and I don't expect you to be out of pocket. As I am using 1/4" silver steel for the crank, I will order Imperial ones to suit.
-
Not at all Ray….
It was my mistake after all.
May I suggest you try your Silver soldering on a piece of scrap first? Cast Iron can oxidise in a twink, making further progress impossible.
:cheers: Graham.
-
Just discovered that Graham. Silver soldered everything (or so I thought), then spent ages cleaning up only to discover that the crank pin joints had not taken at all, although the main shaft ones seem rock solid. Pulled the crank pin out, cleaned up the holes in the webs and used a new piece of silver steel. Tried to re-solder, but not sure if it has penetrated the joint. Will see when everything is cleaned up.
Crank is running pretty true but not perfect.
Think I will probably end up scrapping it and starting from scratch with all steel silver soldered construction.
Very frustrating after all the hours of heat treating and machining the hard web castings.
Will just have to put it down to experience.
-
To solder CI you want to get it upto red hot and then allow to cool, the heating will drive the carbon to the surface which then needs to be cleaned off with a wire brush or similar. You can then flux and assemble your crank and this time apply the solder.
-
Thanks Jason. I cleaned up and re-tried after the first failed attempt, but still couldn't get the solder to take so that crankshaft has now been consigned to the scrap bin. I have now made new webs of steel and that should hopefully be more successful. I have opted for a 40mm stroke like you. I plan to put the exhaust port near to the head.
-
Ray, I could not put this image in a PM so will post it here
You need to buy TWO of the 0.5MOD 15T gears, tooth counts selected from the drop down
-
Thanks Jason. I have now ordered them. As a point of interest, how did you secure the one on the crankshaft? The hub diameter is shown as 8mm and if the shaft is 6mm that only leaves 1mm wall thickness for a grub screw. Did you drill through the teeth?
-
I put a 3mm hole part way into the crankshaft so the grub screw is acting more like a pin and taking the drive on it's side rather than risk stripping the thread if it were purely clamping the gear to the shaft
-
Hi Ray.
Sorry for my delayed reply.
As you know I’ve been more than a tad unwell this week. The sideshaft drives a simple Scotch yoke which presents minimal friction to the gear train. My method is to drill a small, say 2 mm diameter hole into the crankshaft at right angles. Just outside of the main bearing cap. A short peg of Steel is then inserted into it. I then carefully drill a 2 mm hole into the gear, end on. You can either choose a peak or trough to place the hole. Using this method the fixture becomes a “ secret “ when the gear is slid over it. The flywheel boss is then butted up against it to complete the operation.
I do remember Mike inserting the capital letter “ G “ in front of the title nattie due to his immense frustration in one email, however Nattie is definitely Gnat power and the sideshaft gear only needs a dab of Loctite to secure it. In fact I would have simply glued the crankshaft together personally.
On a brighter note “ that very nice man “ has been in touch and I’m hoping to receive a delivery before Christmas, fingers crossed.
:cheers: Graham.
-
HI Graham,
You've got me a bit confused there, but I think I get the general idea.
I have just e-mailed you with the following link, which shows a rather good view of a National at a museum in Spain. It clearly shows the main bearing oil cups and the mechanical oiler driven fron the sideshaft.
https://museudeltractordepoca.com/en/portfolio_category/national-gas-engine-co_en/
-
Hi Ray.
Having re-read my post even I’m confused….. :lolb:
Talk about brain fog, more like a Pea souper from back in the day. Regarding the Loctite I was referring to glueing the gear onto the sideshaft only. The valve timing can be set by the adjustable face cam at the front of the engine.
That’s a very fine looking National sporting early HT ignition.
:cheers: Graham.
Edit.
My exhaust port had already been decided by some previous, now forgotten modifications….. But it’s roughly a 1/2” in diameter. Please see attached photos.
-
Thanks Graham. I like the idea of Loctiting the crankshaft, possibly with pins as extra security. Just tried gluing one of the scrap cast webs and a scrap of shaft and they were absolutely solid within a few seconds. It will also save all the cleaning up needed after soldering.
As regards the crankshaft gear, the attached photo shows my Westbury Wyvern gear. A small pin is fitted through the crankshaft and a notch cut in the end of the gear boss to fit it. The gear is then held in position against the pin by the flywheel boss. Is that something like what you were suggesting?
-
Yes, that’s pretty much what I was trying to describe. I was able to get the notch into one of the gear teeth so the peg becomes hidden from view. The point is there’s so little power required into the gear train even a 1 mm peg would be over engineering!
I have just tried to remove the gear from mine to take a photo but the acid “ episode “ has wreaked havoc and the two are now a permanent feature….
:cheers: Graham.
-
Don't think I've heard the acid story.
-
Don't think I've heard the acid story.
Well….
This has absolutely nothing to do with what Jo refers to as the Alyn Foundry special coatings department whatsoever. ;D
Some years ago I needed to do some Nickel plating and one of the requirements was high strength Hydrochloric acid. I bought a 5 Litre bottle of 30+% from eBay. After doing the job I put the bottle on the shelf alongside little Nattie. Unbeknownst to me I had failed to screw up the cap fully tight and the acid vapour reacted with the humidity to produce a highly corrosive mixture that ate into the engine with a vengeance.
The castings coated up quite well but the Steel components virtually disappeared, needless to say the acid is now stored in a suitable area away from my delicates…. :)
:cheers: Graham.
-
That sounds nasty. Definitely keep it away from your delicates!!
-
Making a bit more progress now after the traumas of trying to silver solder the cast iron crank webs. I have made a completely new crankshaft with mild steel webs and stainless shafts and it runs nice and free and true in the bearings. All joints are Loctited and pinned. I have deliberately left the shafts over length until I receive the flywheels and gears and can see exactly how long they need to be.
On checking the squareness of the cylinder to the crankshaft, it was evident that the front face of the bedplate casting was not exactly parallel to the shaft, meaning that the cylinder was not square. In order to correct this, a piece of 3/8" diameter silver steel was inserted into the bearing holes, and the casting then supported vertically with the shaft resting in two V blocks and the base clamped to a 90 degree angle plate. This set-up ensured that when the front face was re-milled, it would be exactly parallel to the shaft, ensuring squareness of the cylinder to the crank.
The cylinder was originally retained in the bedplate with two grub screws on Grahams engine and this was what I did first. I had bored the locating hole for the cylinder a bit over size, as a result of which I found that, to stop the cylinder moving, the grub screws had to be tightened to the point where they were in danger of distorting the cylinder. Having looked at pictures of a full size National, I saw that the cylinder was attached through the cylinder flange with studs and nuts so I have adopted the same approach, although with only two studs as opposed to the full size engine having 4 (or possibly 5). I cannot see clearly from the photos.
-
That’s a nice touch with the cylinder mounting studs and nuts Ray…. :ThumbsUp:
I’ve posted some video of an Otto style cylinder lubricator on the group page for you. The guys gave me a “ virtual “ tour of the Anson museum this afternoon, I saw a Campbell, Crossley and the Furnival in action.
:cheers: Graham.
-
I like the contrast of the blue gray sand castings and the highly finished crank and fixings. Great photos! :popcorn:
-
Good start to 2023, with the connecting rod completed and all revolving smoothly. I checked with Graham what the position of the piston should be at TDC and he told me "just before the exhaust port", so here it is. Couldn't get it any closer! Happy New Year to all.
-
Happy new year Ray.
Indeed a great start, we just need those flywheels from the foundry.
In the meantime I’m guessing you’ll be moving ahead with the shutter arrangement? Oh and then there’s that other “ top secret “ too…. ;)
:cheers: Graham.
-
Looking good :praise2:
-
One for Graham and Jason. Look, oiler cups!! Just hope the superglue holds.
-
They look really nice Ray. :ThumbsUp:
:cheers: Graham.
-
They look fine and as long as friction is low => no heating of the bearings - they should stay there :ThumbsUp:
Per
-
Thanks Per and Graham. There will be no heat Per, as rhe crankshaft runs in two ball races each side and the bearing caps just hold them in place. The oil cups are just dummies.
-
I have been making a bit more progress on the cylinder head and shutter and on the sideshaft. The shutter slide is still to be cut to length and a piece of metal silver soldered on the end, into which will be cut a vertical slot. An eccentric rotary pin on the end of the sideshaft will locate in this slot and push the shutter in and out, opening and closing the flame port.
The photos show the flame inlet port in the cylinder head in the open and closed positions.
-
Hi Ray.
As you’re aware we’re rather preoccupied domestically here at the moment.
I shall get in touch with the foundry again to find out about the flywheels. You’re going to be needing them sharpish….
:cheers: Graham.
-
No rush Graham. Still plenty to do before I need the flywheels. You get things sorted out at home first.
-
The shutter mechanism is now complete and working well. The slot in the vertical gate is 6mm wide and the driving pin is 3mm. This allows the necessary dwell of the shutter in the open position.
-
I like the yoke and pivot method for the shutter, and the dwell it produces, as you say. That's really cool. :ThumbsUp: :ThumbsUp:
The slide looks very solid and nice. I do wonder how hard it is going to be on that pin... the slide has a fair amount of mass. But this is probably a very reasonably sped engine, and the sound and working adds to the interest. I do really like how it looks! :ThumbsUp: :ThumbsUp: :ThumbsUp: :ThumbsUp::popcorn:
-
So it actually works like a Scotch Yoke - simple, elegant and most likely very reliable :ThumbsUp:
Per :cheers:
-
Possible inspiration ?? ;)
You’re definitely going to need those flywheels now Ray.
https://www.youtube.com/watch?v=beIW4E4Emmk
:cheers: Graham.
-
Still a few more bits to do yet Graham. Have just ordered some 2 thou shim for the exhaust valve. Also need to sort out lubrication for the big end as I have used a split brss bearing. Then of course, there are a couple of non-standard extras to be made!
-
Some time ago, Graham suggested that it would be fun to add a mechanical oiler to Nattie to replicate the ones fitted to the full scale National engines. As a complete novice user of Fusion 360, I thought it would be an interesting project to try and design and build one. The photos show the (almost) finished end result, just lacking the full outlet pipe, which will drip oil into the cylinder, and a drive belt to provide drive from the side shaft.
For those not familiar with this type of oiler, the drive pulley is connected to a small crank on the end of which is a short length of chain. The bottom of the reservoir is filled with oil, through which the chain is dragged as the crank revolves. The oil trapped on the chain is scraped off on a slanting length of rod, below which is a cup into which the oil drips and runs out through the outlet pipe.
The beauty of this type of oiler is that the supply of oil to the cylinder is directly proportional to the speed of the engine. The faster the side shaft revolves, the faster the oiler is driven.
It was necessary to build up the cast flange on top of the cylinder as it sloped markedly towards the centre of the cylinder and there was insufficient depth of material to drill and tap for studs. A thick piece of steel was shaped and attached with JB Weld, When set, the top was milled level and tapped and drilled for two 6BA studs,
-
Nattie number 105 comes alive! After one frustrating morning of trial and error with the timing settings, today I managed to hit on exactly the right spot and away it went. The speed is very controllable just by varying the position of the flame, both in distance away and height.
At present there is no lubrication to the cylinder as the mechanical oiler has been removed for modification, but, as Graham has discovered with the prototype, once an initial oiling has been given, very little more is required.
This is the first Nattie apart from Grahams prototype to run, so, as you can imagine, I am feeling pretty pleased with myself.
This is the YouTube link https://www.youtube.com/watch?v=0vBdj2NHh98
-
Well done ray, goes like a good un
-
Over to you now Jason!
-
As I was saying to Graham the other day the latest small Stuart replica is almost finished then I need to get back to Nattie and Little Otto, even more so now as a pile of
rusty specially coated iron for another Alyn engine arrived on Monday.
-
Great first run, Ray! :ThumbsUp:
Kim
-
Good morning Ray.
Congratulations on a fine running vacuum engine. :ThumbsUp:
Yes, there were two built initially and neither of them showed any signs of life some 20+ years ago. Sadly my friend Mike passed away before he could see a runner. His engine, although the second carries the number 112 ( home address number ) and now resides Stateside with his son.
:cheers: Graham.
-
Congratulations with a very fine runner :ThumbsUp: :cheers:
Per
-
Nattie looks very smart in her new clothes. Just a few more jobs to do now, ie. smoke hood/chimney, wooden base, burner, and mechanical oiler.
How about a nice brass Nattie nameplate Graham?
-
Hmmm, now there’s a thought…..
Here’s an example of an early National gas engine makers plate.
A paint job makes all the difference Ray, well done. :ThumbsUp:
:cheers: Graham.
-
Geoff, the curator of the Anson engine museum sent me a photo of the Brass makers that would have been fitted to engines of that era.
As you can see, it is very nicely detailed. The only problem with a casting is that as the size is reduced so the detail becomes difficult to reproduce. ( see attached cast Brass Robinson plate )
I’m toying with maybe a Laser etched plate that just burns off a Black painted background? The prices of lost wax and the like are really prohibitive. It would put nearly 30 % on in kit cost.
Can Any members here suggest an alternative solution?
:cheers: Graham.
-
Etching?
Should go deeper and OK with small size fonts
-
I've a friend with a teeny CNC mill that is excellent at engraving plates. OK - it takes quite while, but programmed to cut several side-by-side, could be just left to get on with it.
Wilf
-
Etching?
Should go deeper and OK with small size fonts
Hi Jason and Wilf.
One of the Alyn group members is having a look at Laser etching some painted Brass sheet. We could simply etch out the lettering leaving a Black background or, etch away all the surrounding areas leaving the lettering covered and use a Ferric Chloride solution. ( see Penultimate number plate )
Using a CNC system sounds wonderful, having had a nice one off from Jason recently. However it would all boil down to the actual cost.
:cheers: Graham.
Edit.
The Penultimate gas engine badge took several hours of painstakingly placing each Letraset letter in place. I used etch resist paint to make the borders. Other combinations of Letraset were used to create the corner “ Spandrel’s “
-
The biggest issue with CNC cutting is being able to get the cutter in between the letters and also into enclosed or almost enclosed areas such as you get with an "S"
For something the size Nattie would need you are down in the realms of 0.5mm dia cutters and likely single flute. these require a very small chip load if they are not to break which puts the run time up. For example that Retlas sign was done with a 2mm ball nose cutter, something like the 36 x 28 image below would just be possible with a 0.5mm cutter @ 0.3mm depth. Run time for just the engraving a little over an hour (subject to testing) which is not too bad for a few but if lots are needed then etching them on an A4 sized sheet would be more suitable - spray resist, mask that can be done on a inkjet printer, UV light and acid.
One of the small imported gantry CNC machines may be able to cut faster due to it's higher spindle speed but lack of guts may mean cuts have to be smaller so not much gain.
-
Following on….
Another Nattie is underway, this one destined for the curator of the Anson engine museum, Poynton near Manchester.
I’m aware that it’s around 25 years too late but better late than never eh? The original version was to become a raffle prize for the Anson’s National Gas Engine Company’s centenary celebrations. As I’ve mentioned previously we just couldn’t get the engine to run successfully.
In the photograph, one of Jason’s flywheel pattern casting fully machined. The cylinder, bored and honed. The bed, roughly fettled and ready for machining.
:cheers: Graham.
-
Looking good Graham.
-
Coming on well but I can't help feeling that something is missing :thinking:
-
After a bit of a rework of the artwork the Natties will be complete. Infact adding this critical part is probably what made mine a runner.
A little bit larger than ideal but could not really go a lot smaller and still be able to get a 0.5mm cutter in and around the letters. These are cut from bending brass so there is the option to mount on the side of the engine frame as per post above or to bent to the shape of the cylinder.
Ray, yours is done and will go in the post early next week.
(https://hosting.photobucket.com/images/v156/jasonballamy/20230410_181655.jpg)
(https://hosting.photobucket.com/images/v156/jasonballamy/20230411_143207.jpg)
-
Many thanks Jason.
-
Wow! Those nameplates look really nice, Jason! :ThumbsUp:
Kim
-
And here's number 105 to complete the set. My thanks to Jason for a superb job with the nameplates. They give a really professional touch. The photos also show my Nattie, number 105, almost complete, just lacking a mechanical lubricator and a nice wooden base.
-
I did see #105 on FB - but didn't quite get it ....
Seeing it on the Engine just looks right :praise2:
Per :cheers:
-
Nattie is looking better and better with each addition Ray, well done.
I’m currently working on one of those little Chinese, hit and miss governed Petrol engines. I’ve been tasked, so to speak with trying to slow it down to a more scale running speed. However with your help in procuring the skew gears from Germany recently I will be getting back to 106.
:cheers: Graham.