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MasterMaker
04-09-2010, 12:37 PM
I have just leafed through Tubal Cain's book on soldering and brazing and I am a bit annoyed.

Aside from mentioning that the shear strength of soft solders are about 2.5 ton pr cm2 there is nothing about what this means in practice.

What is the practical strength of soft solders??

Say you have 2 pieces of metal plate that you soft-solder together over an area of ca. 1 square cm.... does the 2.5 ton shear strength mean that it takes this much to pull the 2 pieces apart???

I know that they use soft-solder to attach fill-spouts to automotive gas tank's so I know that it is strong enough for this.

How strong is soft soldering when it comes to twisting loads, or lift loads?

Does anyone here have a few real-life examples to share?

Evan
04-09-2010, 12:43 PM
You need to define what soft solder alloy you are asking about. It makes a very big difference.

MasterMaker
04-09-2010, 12:58 PM
I was rather thinking about the practical experiences people have had with what ever solder they have used.

As long as the alloy is mentioned it is all info that would be of use and interest to me, and I am sure to many others here.

Mcgyver
04-09-2010, 01:40 PM
that's a conundrum....the practical consideration is the amount of force there is going to be and what the cross section of the soldered area is...which is what Tubal Cain is giving....so you're kind of dismissing what is the practical information without a specific job in mind. That information lets you know that silver solder is about 8-10x's as strong as soft, and gives the hint that the biggest factor in any joint is going to be the area of the solder.

Not that i'm suggesting I do the calcs before lighting the torch, but with that knowledge, its easier to make a judgment. For example, a small area of contact subject to some force, say the end of a scraper deserves silver solder however fixing a largish block temporarily to a plate for use in a full size mill only requires soft solder because while it's lower strength, there's a huge area of contact. Putting and extension on a drill or tap - small area, high force, use silver solder....then there's applications like a brass model gas tank engine - almost no force or high temps, soft solder all the way....you could go on all day but its all derived from the strength such as Tubal states :)

Is there a specific application you're wondering about? beyond pounds per sq inch its hard to be more practical without knowing the specific application

MasterMaker
04-09-2010, 01:55 PM
Cast iron for instance..

I have a floor drill press with an adjustable angle table...

No matter what I do it shifts when applying any level of pressure when drilling ever so slightly of center.(the price of only having enough money to buy chinese tooling I guess :mad: )

Since I only need the table to be at 90 degrees I was thinking about soft solder as a way of making the damned thing stay put without introducing to much heat to the castings.

Evan
04-09-2010, 02:20 PM
Take it apart at the pivot and introduce a gasket made of 320 grit sand paper.

Circlip
04-09-2010, 02:47 PM
A pinned joint would also work, and just as an aside, have you tried soft soldering cast iron (Even the Chinese variety) lately??

Re4gards Ian.

Fasttrack
04-09-2010, 03:11 PM
Cast iron for instance..

I have a floor drill press with an adjustable angle table...

No matter what I do it shifts when applying any level of pressure when drilling ever so slightly of center.(the price of only having enough money to buy chinese tooling I guess :mad: )

Since I only need the table to be at 90 degrees I was thinking about soft solder as a way of making the damned thing stay put without introducing to much heat to the castings.

I like Evan's sandpaper idea. Otherwise, you could venture into the world of scraping. It would be a quick and easy task to scrape the mating surfaces flat and that should allow you to tighten it up.