Shim for liner flange

Part of the day job at present is overhauling a Crossley BW1, 1940's
4-stroke single cylinder diesel, 5" bore with a wet liner.
I've hit a snag in that the liner should project by 2 to 8 thou above
the block face , to ensure the gasket is properly compressed. Tried
the new liner in place today, it is dead flush. I need to make a
shim/joint to bring it up a few thou, snag is of course the liner
flange is only about 1/8" wide. Whatever I make will have to be neat &
pretty accurately to size. The book does rather ambiguously make
passing refernce to a 'special joint' here, I don't think Crossleys
will have any on the shelf :-(
If I can find some suitable copper or steel sheet, how best to do it?
I've got a trepanning tool & so on, but cutting something that thin &
narrow is going to be tricky even sandwiched between other materials.
Wondered about double-sided tape & a very sharp knife tool, but the
d/s tape I have is far too strong to stand much chance of releasing
something that flimsy in one piece.
I've seriously wondered about some sort of metallic epoxy under the
liner flange, skimmed off in the lathe to leave just a few thou.
Suggestions?
Incidentally, the book refers to a nickel-asbestos gasket for use when
cooling with salt water. I've never come across that before. 'fraid we
only have c/a joints in the stores
Cheers
Tim
(Cross-posted to uk.r.e.s & uk.r.m.e.)
Reply to
Tim Leech
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Tim
I think I would use brass and cut it with sharp scissors.
If I read it right, you are making 5" diameter 'washer' with only a 1/4" difference between the inner and outer diameters. 5 thou thick brass shim is more or less midway in the range and should cut easily.
Another method might be to make one on the lathe by parting off. With a sharp tool it should be a doddle.
Ian Phillips
Reply to
Ian Phillips
You have read it right. Actually a bit bigger, 5 5/8" ID, but the idea is right. I have done that sort of thing, in copper, before where the diameter difference was more like 3/8", the end result wasn't as neat as I would want here. Maybe I'm just not very good with scissors
I did wonder about that, decided the chances of getting it off successfully without crumpling were slim. Maybe I'm too pessimistic on that, I'll see what material I have.
I've just discovered that my pack of steel shim is wide enough (just), didn't think it would be. As a first, simple, effort I'll scribe the sizes out deeply & try the scissors on that. (The wife's best dressmaking ones, of course!)
Many thanks Tim
Reply to
Tim Leech
I dont think deeply scribing will help as unless you cut exactly on the scribe it will sort of throw a burr up.
If you go for the double sided sticky tape and treppaning method (dont fancy it myself) you can always lift the shim after cutting with the application of heat.
I have cut stainless shimstock with my wife's Fiscar general purpose scissors with no apparent ill effect.
Ian
Reply to
Ian Phillips
Our metal bashers have a laser cutting machine, they can cut and profile most metals, probably can do brass or copper as well.
I'll ask Mark in the morning to see what they can do.
Peter -- Peter & Rita Forbes Email Address: snipped-for-privacy@easynet.co.uk Web Pages for Engine Preservation:
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Reply to
Peter A Forbes
When making things as thin as this in the lathe, I detach it not by parting off, but by boring the ID out...Makes for a less abrupt detachment & minimizes burrs.
Tom
Reply to
Tom
Tim, Done this loads of time on the Leyland 680's when they had shuffled a liner. Standard shim pack, a set of trammels and decent pair of sissors is all you need. Sissors will cut at least up to 20 thou with no problem Keep away from tin snips, they should be sold as bending tools and not cutting tools -- Regards,
John Stevenson Nottingham, England.
Reply to
John Stevenson
Hello Tim,
many years ago I used to overhaul diesel engines and came across thi problem many times.If the correct shim was unavailable we used to cu one from copper brass or even steel shim stock,clamping a sheet o material on to a piece of hard board,we would use a pair of sprin dividers with one leg sharpened to a chisel edge,and carefully scrib out both circle diameters.Each time going over the same inner and oute circle with a heavier scribe line pressure.If as you say you requir only up to 8 thou.above the block height,the shim material,being s thin,should with careful manipulation, break away at the scrib lines,leaving you with a perfect shim. I do hope this works for you, All the best for now, John
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Reply to
redstar
I soft-soldered some five thou brass to one-eighth mild steel and turned on the faceplate.
Ken.
Reply to
Ken Parkes
Get a bit of scrap ply or similar, and glue the beer can^H^H^H^H^H^H^H^H shim to it using Tesco's value raspberry jelly (16p!) and the wife's iron (very messy, use something in between to keep the iron clean and the wife happy).
Leave ten minutes to cool. Turn on lathe faceplate with sharp knife tool. Hot water will remove it after.
Reply to
Peter Fairbrother
Or you can lick it off. -- Regards,
John Stevenson Nottingham, England.
Reply to
John Stevenson
Did you do a survey of jellies to find that this is the best?
I made one last night, 7 thou steel, with scissors, not too pretty but it'll probably be OK, but the amount of work to remedy things if it isn't leads me to have another go this morning. Thanks for all suggestions, I'll perhaps try a distillation of them.
Cheers Tim
Reply to
Tim Leech
Exactly! Thats the way to do it,even if one Trammel point was sharpened to a fine cutting edge,with the material being so thin and using some pressure you should be almost able to cut through and break the shim away without the sissor option. that is the way I used to do it[some times had to use a large pair of dividers] All the best for now, John.
Reply to
john .j.morton.
Have you tried tapping the shape out of shim over a sharp pattern? Much the same as a gasket.
John
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Reply to
No Name
Have you tried tapping the shape out of shim over a sharp pattern? Much the same as a gasket.
John
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Reply to
No Name
Why not dissolve it off with a solvent e.g. white spitit ?
Etch it out with acid ? Making this up as I go along; you could coat the metal, scribe the inner and outer diameters (both sides ?) then place in acid, and cross fingers. It, might work, but best of all it involves dangerous chemicals...
Reply to
Neil Barnes
Ouch!!
Spent a couple of hours this morning experimenting for my own satisfaction Can't really charge the customer for it all, though :-(
Sharpened up a tool to a knife edge for my trammel/trepanner/whatever you want to call it, stuck some steel shim to a piece of ply clamped to the mill table. Used the mill as I can get it down to about 10 rpm with the inverter drive, plus no bother with changing to a faceplate on the lathe. Went well to start with, but surprised at how wide the cut was getting - then eventually it started tearing the shim. Turned out that what i had assumed to be a piece of HSS (it came out of the right drawer!) wasn't, and it had rapidly lost its edge. Thought it had ground up easily, but I'd picked it out because it was already close to the right shape. Passed on to the next experiment, I was sure that method could be made to work if need be.
Second method was to use a 2mm end mill in the CNC mill, again with shim stuck to some ply. A rotary table in a manual mill ought to give similar results. This cut it out very nicely, except that the second (inner) cut left a substantial burr which was a real pain to get rid of - I reckon the second cut was much worse because the edge was able to lift much more, and was probably flapping up & down as the cutter rotated. Put ply & shim in the oven for 10 mins, it lifted off fairly well with only half the glue left on the shim. Eventually found I could sand this burr off with a Fein Multimaster - this is like one of those detail sanders with a triangular pad, but works at much higher speed & with smaller oscillations. I found I could actually hold the 5 thou, 1/8" wide, shim in one hand & the sander in the other, & remove the burrs without destroying the shim or my fingers. I bought this tool 3 years ago for a particular job, which paid for it, it's come out of its box twice since then but on each occasion it's done what nothing else would do. (no connection, etc, etc...) End result, after a bit of cleaning with solvent, was pretty close to what you would expect to see in a factory made set of joints, and a perfect fit. Very expensive bit of shim, but I've learned from trying and from suggestions made here. More than one way to skin a cat, etc..
Thanks again for all suggestions, no doubt that the manual scissors would be the most cost-effective if only the scissor operator were better trained
Cheers Tim
Reply to
Tim Leech
A very interesting thread which I've enjoyed reading. Problem solving is what it's all about after all - but I would never have realised a cheap jelly made a first class engineering glue!
Regards,
Kim Siddorn
Reply to
Kim Siddorn

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