how it used to be done
|Anthony Knights||05/06/2019 07:09:31|
|622 forum posts|
A lot of projects these days use modern adhesives such as anaerobic retainers to hold parts together and wondered how it was done before these products were available. I would assume it was a combination of different design, interference fits and various soldering / welding techniques.
|Philip Burley||05/06/2019 07:34:48|
198 forum posts
I did read somewhere that men used to pee on parts before pressing them together seems to encourage rusting !
6414 forum posts
Soft solder was often used in model engineering. Its strength is greater than Loctite's, so it's still a good choice in a joint with good surface area. Just not as convenient to use, needing a torch etc.
But many old model engine plans show they relied a lot on interference fits -- probably most often pressed together in the workshop vice, and on grub screws and woodruff keys.
|Michael Gilligan||05/06/2019 07:46:44|
20190 forum posts
Perhaps a rather broad generalisation, given the range of Loctite products
|Nicholas Farr||05/06/2019 08:01:19|
3361 forum posts
Hi, I had to use Araldite in my day job back in the seventies, which had two parts that had to be weighed out in the correct ratio, this held a taught stainless steel screen cloth onto a circular 5 ft frame which fitted in the machine. It held very well, but its downside was it only took moderate force to peel the cloth off, the peeling aspect was an advantage though, when it was time to replace the worn out cloth.
|Neil Wyatt||05/06/2019 08:25:50|
19040 forum posts
Lots of different takes on line, but soft solder seems to have the edge. Also, I found one reference to soft soldered copper-to copper joints having a strength of 200MPa.
Loctite 3422 at various cure temperatures:
|Michael Gilligan||05/06/2019 08:41:01|
20190 forum posts
An interesting choice of Loctite product, Neil
Which, I think, supports my point.
P.S. the 'Pin and Collar' Test is highly relevant to some [not all] 'model engineering' applications:
Ref.1 is costly
Ref.2 can be found online
Edited By Michael Gilligan on 05/06/2019 08:55:53
|Mick B1||05/06/2019 08:47:01|
|2192 forum posts|
Most of the old methods - drive fits, rivets and upsetting, cross pins etc. - are still in use. I can remember first coming across superglues in the mid 70s for bonding the ends of O-rings in injection mould cooling circuits. Their general usefulness has expanded a good deal since then, but where you need to be sure to be sure, and you don't have comprehensive and detailed knowledge of the value and direction of stresses, it's best to add something you can be more certain of.
|John Haine||05/06/2019 09:08:40|
|4679 forum posts|
I use soft electronics solder a lot, especially in conjunction with a non-corrosive white paste flux. For example, fitting "brass "collets" into wheels on the clock I'm building. Make the two parts a good fit; apply a little fux into the joint and fit together; cut small piece of fine cored lead-free solder and wrap round the shoulder where the two parts mate; and apply gentle heat with a torch. Takes less than a minute to reach temperature, solder flashes into joint, job done.
Normal "Araldite" type epoxy also very useful. I have a storage heater in the workshop, when I've assembled the parts together with the glue I pop it on top of the hot heater and leave overnight.
|Clive Foster||05/06/2019 10:05:02|
|3135 forum posts|
Although the nominal joint strengths are very similar one important difference between adhesive bonding and soldering is peel strength. Adhesives are generally much weaker than solders in peel because very high stress concentrations can be developed at the separation point between the bonded surfaces. Sufficient to tear the bonding material apart or pull it off the surface if initial preparation was inadequate. A little bit of additional mechanical locking at the ends of adhesive joints is often appropriate.
Oversimplifying adhesives rely on surface wetting to generate the bond strength whilst properly applied solders have a degree of inter metallic penetration which is inherently far more resistant to localised joint line stresses. Its not actually that much stronger. You just can't build up the localised stress. Peel is good test for improperly tinned and improperly heated soft solder joints. The joint may look fine but if it hasn't taken properly it will peel quite easily. One of my mentors showed me that many years ago. Much to my surprise as I thought I'd made a nice neat joint. Big electric soldering irons aren't quite as easy to use as I'd thought.
Adhesive joints can be amazingly strong as its relatively easy to cover quite large areas. The achilles heel in the home shop is surface preparation and environmental factors. Usually temperature. Its hard to achieve and maintain optimum conditions in the home shop.
|vintage engineer||05/06/2019 10:09:08|
258 forum posts
We used to put solder paste on clean threads, assemble and then heat to melt solder. They were a right bugger to get apart!
Edited By vintage engineer on 05/06/2019 10:09:34
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