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Silver Soldering Leaf Springs

Posted: Wed Jan 15, 2020 7:21 pm
by rhbroehl
Have a quick question.

I need to solder bolsters to the ends of my leaf springs for my LE 0-4-0. What silver content do I need to use to make sure these will stay put and not break off in use?

Thanks

Rob

Re: Silver Soldering Leaf Springs

Posted: Wed Jan 15, 2020 8:56 pm
by michaellynn2
I used 45% silver solder on my LE Pacific leaf springs. I made sure to rough up the area on the spring leaf to get a good joint. My springs had an oily film on them so a good cleaning was in order. It has been over 30 years ago that I did the job and all is still good and solid.

Re: Silver Soldering Leaf Springs

Posted: Wed Jan 15, 2020 9:24 pm
by Bill Shields
any silver solder will work as long as you do it correctly.
springs 2.jpg
FWIW I always remove the 'blue' from the surface and ASSUME that the leaf to which the soldering is done is no longer a spring (at least on the end).

Re: Silver Soldering Leaf Springs

Posted: Wed Jan 15, 2020 11:54 pm
by Greg_Lewis
Also, I've learned the hard way that the metal needs to be hot enough to melt the solder. Heating the solder to melting when the parts are not hot enough will not give a good joint. Heat the metal with the torch and let the solder flow into the joint. I would do this on your project by placing the parts atop a piece of, say, 3/16 thick angle held in a bench vise and heating the angle from the underside with an oxy/acetylene torch with a long feather on the flame. Yes, I know that o/a is not recommended for silver soldering but that's because it's easy to get things too hot. But if you heat the parts by conduction through the angle, you'll be fine. I do this all the time.

Re: Silver Soldering Leaf Springs

Posted: Thu Jan 16, 2020 4:39 am
by Harold_V
It should be obvious to all that heating any spring material is going to alter its ability to behave as a spring. It is generally just medium to high carbon steel, so it gets annealed by the heat required for silver solder to melt. Any quenching offers the risk of failure due to fracturing upon flexing.

I've read that folks have soldered on their springs with success. I have to assume that only one piece is heated, which, if allowed to cool slowly, will be softened, but the balance of the leaves will still function. Do I have it correct?

H

Re: Silver Soldering Leaf Springs

Posted: Thu Jan 16, 2020 8:03 am
by Bill Shields
yes Harold...you are correct...

as I said... assume that the top leaf is no longer a spring...

cannot say that I have ever had a failure....

Re: Silver Soldering Leaf Springs

Posted: Thu Jan 16, 2020 8:24 am
by Mike Walsh
Given the content of this thread, I just reflected upon my memory of the construction method for the LE springs (at least, in 1" Scale for the pacific/0-6-0 variants)...

There is a single leaf spring that gets this sort of block/pivot point silver soldered to it. But when assembled in the stack, the silver soldered spring is stacked upon another leaf spring of the same exact dimension. I think this is how one gets away with still having the same leaf spring, but in an unaltered state....

Re: Silver Soldering Leaf Springs

Posted: Thu Jan 16, 2020 11:29 am
by Bill Shields
kind of like the picture I provided?

I am no familiar with the LE 1" models at all

Re: Silver Soldering Leaf Springs

Posted: Thu Jan 16, 2020 1:35 pm
by Mike Walsh
Bill Shields wrote:
Thu Jan 16, 2020 11:29 am
kind of like the picture I provided?

I am no familiar with the LE 1" models at all
Yep. Sorry, didn't look close enough. Good example!

Re: Silver Soldering Leaf Springs

Posted: Thu Jan 16, 2020 4:48 pm
by Bill Shields
I am duplicating something from a free lance model built in 1966.

the springs are there, and work on the front driver axle...but the rear axle, because it is SOUTHERN valve gear - has been blocked solid for 54 year..so the springs are 'decorative'...runs good...who cares?

Re: Silver Soldering Leaf Springs

Posted: Thu Jan 16, 2020 6:54 pm
by rhbroehl
Thanks for all the replies. As mentioned, I am not concerned about losing the "spring" in the leaf since it is backed up by 2 others the same length. My concern was the silver content of the solder. I think I used 5% and wasn't sure that was enough to give a good solid joint.

Rob

Re: Silver Soldering Leaf Springs

Posted: Thu Jan 16, 2020 7:24 pm
by Fender
The low-silver content solder is not what you want. This is not a "hard" solder (silver brazing) but a "soft" solder that does not have sufficient strength. The high-silver solder is usually an alloy of silver and copper, zinc and sometimes cadmium, and has much higher strength. The higher silver content makes it flow better into the joint. Expensive per ounce, but you won't need much of it.