a gluing quandry

This topic has 11 replies, 7 voices, and was last updated 13 December 2021 at 21:03 by Joseph Noci 1.

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6 December 2021 at 20:46 #574510
duncan webster 1
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@duncanwebster1
I'm plotting how to hold an assembly of fiddly little bits together whilst I drill through and rivet. Using epoxy resin would be good, but if I clamp them up tight whilst it sets won't it squeeze out all the glue? It needs 6to be up solid so I can then drill and rivet

It's the assembly of expansion links and side cheeks for Walschearts gear. Any other ways of keeping the pivot spigots in line appreciated

Edited By duncan webster on 06/12/2021 20:46:50
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6 December 2021 at 20:46 #28458
duncan webster 1
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@duncanwebster1
6 December 2021 at 20:55 #574513
Oldiron
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@oldiron
You will never squeeze out ALL the glue. Not tried epoxy but I have used superglue in the past to hold small parts.

regards
6 December 2021 at 21:04 #574515
Bazyle
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@bazyle
Even if mirror smooth the surfaces at microscopic level are full of pits and craters full of glue. Clamping tight just means you can use less glue.
6 December 2021 at 21:51 #574522
Jeff Dayman
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@jeffdayman43397
An assembly jig with V blocks for the pins, and mating clamps, plus datum plates and mating clams, would be a good solid way to go bout it, but that is a lot of work for a one-off engine. If making a batch of similar valvegear for other modelers, the jig would be worthwhile. Just food for thought.

Designing and making such jigs for difficult or near impossible assys was a big part of my day job in industry in the early years of my working life. There are a few tricks, one of them being that you can have "leaves" on the jig that slide in and out in gibs (or just with slots on shoulder screws if high precision isn't required) to engage and disengage the assy to get parts in / aligned and then back out again. Start with a smooth flat datum surface on a base plate, and build up from there. Such a plate and attached parts can always be turned vertical or angled after the fact if need be.
6 December 2021 at 22:22 #574525
Michael Gilligan
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@michaelgilligan61133
The traditional horological adhesive for such jobs is Shellac

MichaelG.

.

P.S. __ as a StressMan, you might like this:

http://14.139.215.35/~lpd/library/bulletin/Bulletin%20No.%20-210.PDF

Edited By Michael Gilligan on 06/12/2021 22:41:36
7 December 2021 at 08:26 #574541
Bo’sun
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@bosun58570
Andrew Whale (Learning Turning Metal) often uses superglue to good effect for temporarily holding small parts. Clean, well fitting joints with the largest surface area you can is the key.
7 December 2021 at 19:14 #574608
duncan webster 1
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@duncanwebster1
Thanks for replies, I'll report back when I've done it
9 December 2021 at 23:13 #574846
duncan webster 1
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@duncanwebster1
Michael, who said I am a stress man? Wouldn't know one end of an FE model from another. I only do the sort of sums most design engineers can cope with if they put their thinking caps on.

In one of my early jobs the Chief Designer reckoned that sums were the last resort of the incompetent. I wouldn't agree, but for most things if you can't design it using the information in Roark, redesign it till you can!
9 December 2021 at 23:51 #574850
Michael Gilligan
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@michaelgilligan61133
Posted by duncan webster on 09/12/2021 23:13:33:

Michael, who said I am a stress man? …

.

Apologies … it was my inference from previous discussions

MichaelG.
13 December 2021 at 18:21 #575292
duncan webster 1
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@duncanwebster1
The answer to assembling the expansion link came to me whilst walking the dog. Taking Jeff's rather elaborate suggestion, I already have an assembly fixture in the expansion link bracket, all I need is a toolmakers clamp with 3 holes in it to allow me to drill though in situ, simples. The spigots cannot help being in line with the bearings, and they were line reamed. Another case of me overthinking problems?
13 December 2021 at 21:03 #575314
Joseph Noci 1
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@josephnoci1
As was mentioned, you wont get all the glue out from the joint no matter how hard you can clamp it – also, other effects then apply as well – think what happens when you wring two gauge blocks together – almost impossible to pull apart, and there's no glue..
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