andypugh
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Posts posted by andypugh
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The brass part in the picture has a parallel section of only an inch and when I have tried for more the brass has torn or wrinkled up.
I _think_ that there are two processes at work and you need to balance them.
You can lay the disc down on to the former. This keeps the material thickness the same, but creates wrinkles as the overall diameter reduces. This is what happens when the tool is relatively far from the former.
Alternatively, you can stretch the material along the former. This is what happens when the tool is hard against the former and you push towards the chuck. This is (I think) the process of shear-forming which looks a bit like spinning, but isn't.
You need to play these effects off against each other. It is interesting to note that the open ends of my headlights are rather thinner than the starting material, but the lampholder bosses have come out rather _thicker_ than the starting material.
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All done in one go? What sort of speed?
All in one go, though I did experiment with an extra annealing for the super-difficult lip. This is a picture of an original one:
I think I pressed the "speed up" button 3 times, so that would be 300 rpm. I know things went better when I slowed down a bit, so it isn't wood-turning speed.
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They look fine, Andy. What speed did you use and what sort of tool?
A hardened steel tool, but also a roller and a beader. Actually the roller and the beader are the same home-made tool but with the roller swapped.
The lamps with a spigot were done in two stages. I found a bit of inexplicable plastic in the box (the patterns have been used a few times before, generally by pros) and it turned out to be a collar that spaced out the spigot to the main shape so that it was possible to get a "touch" on the main body before the tool torque ripped the spigot-end out. Then the spacer was removed and the spigot rolled to final shape.
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If it proves impossible even after a little gentle heating for expansion, you can always drill the crown, it needs a hole to bolt onto the kingpin top anyway, tap it for air or grease fitting, epoxy up the air hole in your mandrel, then blow it out with a grease gun or airline.
I am glad I read this far before replying, I was about to suggest the same thing.
Air will slightly expand the part and provide a nice air-bearing effect. But grease might be less exciting.
My recent attempts at metal spinning have produced a lot of scrap:
https://picasaweb.google.com/lh/photo/LBoi5b4CsBt_EFhiK0EPftMTjNZETYmyPJy0liipFm0?feat=directlink
But also some usable parts:
https://picasaweb.google.com/lh/photo/JqMiezKZO-Cwmt1JMMShgdMTjNZETYmyPJy0liipFm0?feat=directlink
(The Ner-a-Car has one acetylene light and one new-fangled electric one)
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I couldn't resist a bit of Googling, and it seems that Robbialac is still a paint brand in Portugal, and that Jenson and Nicholson are still making paint, but in India rather than Stratford.
I wonder if they have any old stock? http://www.jnpaints.com/product-industrial.php
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I googled too (and remembered that I have done the same search before).
This article is fascinating:
It appears that "It goes with out saying that" and "It is self-evident that" means "This journalist has no idea why"
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Top Tip! You can make a tool for the Dickson Toolpost clamps by bending a big Socket Head Cap Screw ;-)
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I have used carbide lighting extensively, it is still not quite a defunct technology for caving use.
Here, for example, is a brand-new caving light set: http://www.trolluk.com/outdoor/head-touches/item/86-acetylene-cavers-lamp
The flame is quite cool (takes ages to burn through a rope, luckily) and the gas is pungent enough that you are unlikely to build up a dangerous concentration without noticing.
The best light for vehicle use uses two impinging flames, and is very bright without any need of a mantle.
It's a lovely light to cave by, though I haven't yet tried driving with it (I am at the moment part way through making a lighting set for my 1921 Ner-a-Car, which has dual electric / acetylene lighting).
You can get carbide from various sources still, including Amazon and eBay.
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Is there such a thing as corrugated shim?
http://www.euro-bearings.com/tol1.htm
My dad has a horizontal boring machine, exactly the right machine for the job. The only problem is that it is in Yorkshire. (and generally buried under other stuff)
https://picasaweb.google.com/lh/photo/lorjlRbUi9B2VQy0Cd0KcNMTjNZETYmyPJy0liipFm0?feat=directlink
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An easy way to make a one-off internal spline is with CNC wire spare erosion. (clearly unless you have the machine that would be a bought-in job). If you supply a machined bore the wire-eroder can align to that and cut the grooves pretty quickly.
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Steve has a Ball-Turning attachment for his lathe and he will have a go at doing it with that! I don't think that he has attempted anything quite as big as this before - so we shall see how he gets on!
If it doesn't work out, I have a CNC lathe.
I am also willing to have a go at re-machining the thrust race/bush things if you want. I think that with CBN tooling and CNC it might be possible to re-cut the ball track.
Whilst I am at it, we re-machined the transmission brake shoes for Jez (1916 Dennis) using my dad's horizontal borer. Though I imagine that it wouldn't be too hard with a lathe, face-plate and jig.
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One thing that I have noticed about the FIAT is that everything is a step above Dennis for quality and complexity.
And this thing I have been pointed at looks like another step again.
Not military, but what a monster:
http://jalopnik.com/watch-a-28-5l-fiat-start-for-the-first-time-in-a-centur-1665309191
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Thank you David for the description of railway tyre making,. As you say it would be a logical step to use the same process for vehicle requirements.
It was even the subject of a "How it's made"
There are still companies in the UK that makes them (Doncasters for example) though you have to be careful not to get them confused with "Ring Mills" which were different.
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I would hope that the hoop stress is well below the yield point!
I wouldn't bet on it. There is a lot to be said for letting things size themselves, and solid tyres seem like a case where allowing yield in the relatively weak band would be a good way to cater for wheel size tolerances while ensuring the maximum grip.
For most steels the tensile strength increases after yield, so until the reduction in area is significant the load carrying capacity of the component increases, and the stress distribution is equalised.
But maybe a real mechanical engineer should step in, I just play one on the Internet :-)
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It would follow that the load required to press them off was dependant not only the width of the tyre section, but its diameter..
You would expect that, but it might not actually be true.
The limiting factor is the hoop-stress in the hoop. Assuming that the hoop is at its yield point, then the hoop stress depends on the hoop cross-section, ie width and thickness.
The frictional force depends on the radial component of the hoop stress. Classically friction = (mu) x R. Notably the surface area does not feature in the equation.
So, a wider hoop may be under more tension, and will grip the wheel more tightly, but there will not be any more friction.
However, it gets even more counter-intuitive than that. As the diameter increases the radial component of the circumfrential stress reduces, so a larger ring of the same thickness and width will actually grip less tightly than a smaller one.
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Nice thing - does it run?
I didn't push it there!
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We didn't actually get to the limit of the gauge. At least, I don't think we did.
Barry's post has a table of loads and pressures, and peaks at 20 tons which is more like I would have expected.
However the PSI numbers on a 14" ram don't seem to match at all.
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Not entirely on-topic but I took my 1921 Ner-a-Car to Stowe-Maries on Sunday so that a photographer friend had some backgrounds to use.
(It was also good to see the progress with the FIAT, which actually looks less complete than last time, because more parts are off being fettled).
Anyway, here are the pics. You can tell that he mainly does weddings :-)
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Thanks for any ideas received.
Those rivets don't look to me like they ever held anything on.
Unless the have slop and have dropped into the countersinks then there doesn't seem to be any gap for the rivetted-on item to have lived in (if you see what I mean).
I wonder if the rivets were a stop-gap measure to provide a new wear surface (the actual rivet heads).
Is there any sign of anything trapped under the remains of the heads?
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The ram is 14" diameter and the pressure gauge is dual calibrated in cwt/in² and Ton/in² up to 2 tons! We used all of it to get the rear tyres started as Tim will tell you shortly.
So, 2 tons per square inch on a 14" ram sounds like 300 tons. That's a fair bit more than I would have guessed.
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The only additional Champ item I picked out was a headlamp bowl, where are you located ?
I am in Essex, the parts are in Yorkshire.
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I think I recognise that press, and have spent some time cranking it myself.
It is probably actually a good deal bigger than it needs to be.
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I picked up the instruments last weekend, and I hope to give it a clean and inspection this weekend.
There appears to be most of a wiring loom attached, which might be more useful than the instruments.
Adjacent to where I picked it up from were some crates of other parts. Does anyone recognise anything useful?
https://picasaweb.google.com/lh/photo/AX4mDJkaf7D2REeY_BASrxc7VCAtwh2s5FgFYEWXI3g?feat=directlink
https://picasaweb.google.com/lh/photo/kBVEghtlnVX2cV8Ff_2nxhc7VCAtwh2s5FgFYEWXI3g?feat=directlink
(clearly not all Champ)
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you can occasionally see pictures of them at work are the Salvation Army, Red Cross and Knights of Columbus to name but a few.
Off topic, but I can't help wondering if they were:
http://en.wikipedia.org/wiki/Knights_of_St_Columba
rather than
WW1 Thornycroft restoration
in Pre WW2 vehicles
Posted
I guess it keeps the edge more homogenous, and so cracks and wrinkles are less sure where to start.
The spinning videos all seem to do a lot of edge trimming with a tool for the job, so it shouldn't be too hard to trim to perfect circles when mounted and "set on" the former.