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Caliper friction washers

What are they made of and how to replace?

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Grindstone Cowboy20/01/2020 22:46:43
194 forum posts
11 photos

Been cleaning up some tools I inherited a while ago, and found that some of the larger Moore & Wright calipers have a friction washer of some sort under the domed nut. This unfortunately seems to be breaking up and coming out, which will make the joint a lot looser.

So, what are they made of (looks like some sort of fibre or heavy paper to me), and how best to replace them?

It looks like I'll have to grind off the peened over end of the joint screw, but will I do more harm than good - will there be enough thread left to reliably re-assemble? Are they actually necessary and once they have fallen out, could I just tighten up the joint by tightening the hex head screw?

img_3169.jpg

Thanks.

Rob

old mart21/01/2020 15:27:31
1101 forum posts
113 photos

If you can make a screw on cap for the hinge, you can try different friction materials. Occasionally there is a black very hard thin paper based card in the packing of certain products, a bit like fibre washers, that might work.

peak421/01/2020 15:45:56
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987 forum posts
98 photos

You could try looking up Belville or Crinkle/Wobble washers.
Some of the latter are quite thin and my be available in suitable sizes.

Bill

Grindstone Cowboy21/01/2020 23:56:59
194 forum posts
11 photos

Thanks guys, I'll have a go at taking one apart. The Belleville washers sound like a good idea, or I've been wondering if a washer made of plastic (from a milk container, maybe) would give a stiff but movable joint.

Clive Hartland22/01/2020 07:50:21
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2503 forum posts
40 photos

The soft plastic you are thinking of will likely extrude and break down, better to have a stiff solid materiel as a friction washer. Vulcanite comes to mind if you can find some thin enough. easily dressed down to a thickness required.

Hopper22/01/2020 09:11:59
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3989 forum posts
85 photos

Red fibre washers? Or cut your own specials from a sheet of red fibre material that you can buy at engineering suppliers. (No idea if there is a proper name for that red fibre, that's all I've ever heard it called.)

Or you might investigate what type of friction material is used in steering dampers on vintage motorcycles. Many had a disc 2 0r 3 inches diameter of friction material about 1/16" thick that was clamped between two steel surfaces by a big knob on a threaded rod coming up through the steering head.  Probably available from vintage parts suppliers for AJS, Matchless, BSA, Triumph etc etc. One steering damper disc would supply enough material for a bunch of caliper sized washers.

Edited By Hopper on 22/01/2020 09:19:30

Russell Eberhardt22/01/2020 09:28:22
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2534 forum posts
85 photos

How about this: **LINK**

https://www.vintagecarparts.co.uk/products/ca584-hard-red-fibre-sheet-0-8mm-thick

Russell

Edited By Russell Eberhardt on 22/01/2020 09:29:05

Bazyle22/01/2020 09:36:00
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4905 forum posts
195 photos

Maybe a bit of leather from an old shoe or belt. Definitely what would have been used before they invented plastic. Make a new longer screw with a locknut.

Grindstone Cowboy22/01/2020 20:58:58
194 forum posts
11 photos

Many thanks for all the ideas and information, I'll look at getting some of that fibre sheet.

Grindstone Cowboy24/01/2020 17:43:29
194 forum posts
11 photos

Hi All

Disassembled one of the calipers - as it turned out, I picked one where the washers were still intact, but never mind. I found the screw is not peened over, so that's a good thing, and the washers are 5/8" OD, 3/8" ID and 15 thou thick (measured at 14 but assuming some compression has occurred). Cleaned and reassembled, good as new. Took some pictures if anyone is interested, not sure how to add an album to a posting, but I think you can see them if you click on my username.

There seemed to be some writing on the friction washers, which were quite a tough material, white in colour, which said (I think) "TENNEX", but cannot find anything relevant with a Google search.

XD 35125/01/2020 03:55:45
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1392 forum posts
118 photos

FYI on red fibre washers .

https://plasticwashers.newprocess.com/product/custom-washers/vulcanized-fibre-washers

Ian S C25/01/2020 08:14:12
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7468 forum posts
230 photos

I m,ade 150 pair of calipers for the Christchurch Indoor Bowls Ass, I put a washer made of shim brass (about .010" Between the legs, and held them together with a brass rivit. Seems to work OK, just a light tap on the rivit if it gets a bit loose. I have never looked at my Moore & Wright gear, but I would go with Clive, a hard plastic.

Ian S C

Grindstone Cowboy26/01/2020 20:41:35
194 forum posts
11 photos

Thank you all for the insight and suggestions, I may well go with some brass shim.

Cheers, Rob

ega26/01/2020 23:00:46
1444 forum posts
118 photos
Posted by Ian S C on 25/01/2020 08:14:12:

I m,ade 150 pair of calipers for the Christchurch Indoor Bowls Ass, I put a washer made of shim brass (about .010" Between the legs, and held them together with a brass rivit. Seems to work OK, just a light tap on the rivit if it gets a bit loose. I have never looked at my Moore & Wright gear, but I would go with Clive, a hard plastic.

Ian S C

Presumably, the calipers were for measuring woods?

Kiaora!

Grindstone Cowboy26/01/2020 23:09:49
194 forum posts
11 photos

Comparing the distances 'twixt woods and jack, I would guess - I inherited a handy little string and ivory gizmo for the same purpose from my grandfather.

ega27/01/2020 15:32:45
1444 forum posts
118 photos
Posted by Grindstone Cowboy on 26/01/2020 23:09:49:

Comparing the distances 'twixt woods and jack, I would guess - I inherited a handy little string and ivory gizmo for the same purpose from my grandfather.

I expect you are right but one would need a steady hand to avoid disturbing the status quo (I assume they were firm joint calipers).

Grindstone Cowboy27/01/2020 22:33:18
194 forum posts
11 photos
Posted by ega on 27/01/2020 15:32:45:
Posted by Grindstone Cowboy on 26/01/2020 23:09:49:

Comparing the distances 'twixt woods and jack, I would guess - I inherited a handy little string and ivory gizmo for the same purpose from my grandfather.

I expect you are right but one would need a steady hand to avoid disturbing the status quo (I assume they were firm joint calipers).

Of course, you don't need to measure if you can do this wink

Georgineer30/01/2020 15:04:03
310 forum posts
16 photos

Vulcanised fibre was actually patented in 1859 and is available in a number of different colours. It's amazing stuff.

That said, I have various calipers made by my grandfather in the early 1900s with no shim or washer in the joint, and they are still in regular use. All that's needed is enough oil to prevent rust in the joint, and a tap with a hammer every generation or so to take out any looseness.

George B.

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