Silver soldering steel balls

[1937 Chief]

I need to make four pushrods for a old motorcycle I am working on. If I silver solder a hardened ball on the end of a 5/16 in. drill rod will the hardened steel ball lose it's harness? Thanks for any info. stan

[ironmonger]

Brazing or silver soldering the balls to the end of the push rods will take the parts beyond the critical temperature, which would result in them losing their hardness as the parts would need to be cooled slowly so as not to ruin the solder joint, thus annealing them. To re-harden the balls would require heating to a higher temperature than the solder joint will stand.

If you can find an alloy steel ball that would be hard enough in the annealed state this method could work.

The only alternative would be either spin welding or spot welding the balls to the end of the drill rod.zone


Were the original push rods solid?
How were the original push rods formed?

paul

[Mcgyver]

they're very close; annealing temps and silver soldering temps. If you sought out the lowest temp silver solder (some are close to 1100F iirc) it may work but things will certainly be fully tempered. It also matters what the hardened steel requires for a quench or annealing; ie air hardened with a high heat silver solder might quench just from removing the heat after silver soldering. I've re quenched hardened steel by wrapping a wet rag around the silver soldered area and heating red hot the target area then quenching the end in oil/water, but its iffy - whether it'll work and wether it'll mess up the the silver solder joint

A more exact answer depends on what steel and what silver solder, still it'll be dicey no matter how you do it. I'd be thinking grinding a forming tool and putting the ratius on in the lathe used a chrome moly steel then heat treat.

[1937 Chief]

Ironmonger From what you said I thought that would be the problem. As for the original push rods they had hardened pieces with a ball shape on the end, and a round part below the ball. They were pushed into a hole in the 5/16 rod. I guess I can remove these ends if nothing else is available. Stan

[ironmonger]

Any chance you could fixture the rods and balls and TIG them on? You might need to re-harden and temper them but they certainly wouldn't come off...
paul

[Hogridnfool]

Did you consider having them custom made? http://www.pushrods.net/

[RussZHC]

I quick checked the pushrods site as I seemed to recall...the answer maybe to make the balls on the end of a threaded (column) and thread the rod itself internally...to me it would solve both conflicting issues of silver brazing.

[macona]

If its drill rod just turn balls on the end and harden the ends. Thats what drill rod is for, hardening.