Bi-metal bench block

Brass and steel? You almost certainly have to solder. Maybe you can get by with something like Silphous 15, but I would bet on an acid paste flux and a separate silver solder. Atleast you aren't upside down and sideways behind a condenser. You can do it on the bench. You might be able to use generic plumbing solder, but you did say "stay together."

Nah, ignore all that' I don't know nuthin'!

I just happen to have a few sticks of silfos 15 out in the shop ... and some boric acid flux . But now ya got me thinkin' , how about phosphor bronze TIG filler ? I've got some silver solder here somewhere , but I haven't seen it in a couple or five years now - got it to repair/make some bandsaw blades and misplaced it almost immediately . I've also got regular brass brazing rod on hand . I'll still have to cast a slug for the brass side , which is why I was thinking about casting it right onto the steel .

My friend the jeweler did me a real solid on my wife's Christmas gift , and I want to do something for him . Jewelers can never have too many bench blocks , and I'd like to make him a sorta special one . My idea is to make one that's steel on one side and brass on the other . Probably around 2 1/2 to 3" in diameter and around 3/4 - 1" thick . My concern is the bond between brass and steel . My first idea was to cast the brass to the steel , then machine to final size . This will mean preheating the steel so the brass doesn't chill and solidify too soon . The only way I can see this working is to machine a recess in the steel or to clamp a band around the preheated steel disc . Probably need to flux and prime with some brass brazing rod too . This thing will be hammered on , so I doubt any kind of epoxy or other chemical bond will hold up for long . The brass side will have vee and maybe half-round grooves plus various size holes for pin punch operations . The steel side is for stamping or flattening type stuff . Ideas on forming a lasting bond are welcome ...

Given the differences in thermal coefficients of linear expansion, I'd do this mechanically, by machining a threaded post and threaded recess into which the post screws, and fix it all together with stud locking locktite.

Joe

Silphos 15 is supposedly self fluxing. I found I was able to solder copper on the bench with it without flux anyway. I didn't have so much luck with out of position soldering.

I was thinking brazing might not be that great since you will be running brass on brass. Brazing is more like soldering (should be) than welding. Same on same is generally welding. even with a torch. I used to torch weld mufflers with coat hangers.

I totally missed that. If you find the right preheat temperature for the steel and maybe a flux it might be the best result. Maybe even machine the steel to keylock with the brass when its cast.

All of that being said, I was wondering if a simple mechanical connection might be as good as anything. He's not going to be beating on a bench block with a 3lb machinist hammer, and he's not to likely to be heating it directly either. You might be able to get away with pinning the two pieces together with some sleeve and bearing locker.

I have a small bench block I use for tapping out pins on firearms, and the heaviest hammer I have ever used on it is about 3 ounces. The same hammer I used with a punch to peen screw slots back into a usable condition for removal.

You aren't making a blacksmith swage. You are making a jewelers bench block.

You aren't making a blacksmith swage. You are making a jewelers bench block. Bob La Londe

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You never know. Today I tapped the pins out of three loose pin hinges easily; the fourth had rusted and took several good whacks to loosen it.

As Jim suggested , a keylock machined feature . As you suggest , a preheated steel block and flux for the pour . I think I'm going to use a mix of bearing bronze shavings and some faucet chunks . Cartridge brass is probably too soft for this piece . This guy has been really good to me , bought a few pieces of silver , a couple of jewelry purchases for my wife . And a jeweler can't have too many bench blocks . That'd be like a mechanic having too many wrenches or a blacksmith too many hammers and tongs !

Or as Jim suggested , a machined feature that the brass can shrink to fit tightly as it cools . That T/C can work for you or against you ...

If you're feeling really generous... offer to make an improved version after he has had time to work with this one and see where changes could be made...

I've already got a couple of things that I'm not seeing on commercial blocks .