Sweat Brazing?

Absolutely nothing wrong with "sweat brazing". I've done it for years, and if the fit is reasonably close you get the same effect as a "furnace brazed" joint.

Needed to join two pieces of mild steel today, with minimal bead and as strong or nearly so as the parent metal.

So I got each one hot, got a thin coating of brazing rod melted onto each one, then slapped them together and heated the back of the accessible piece.

Poof! Instant bond. What a joy brazing is.

Is this an accepted procedure? Are there any pitfalls that I should know of? How likely is it that I've got a joint that's mostly flux?

(It's totally not anything-critical, except that it's part of a stand for painting a model airplane -- so the worst that will happen if it fails is that the air will turn blue.)

What's that Lassie? You say that Tim Wescott fell down the old rec.crafts.metalworking mine and will die if we don't mount a rescue by Sun, 12 Sep 2010 15:16:24 -0700:

Yes. It would be called tinning if it were soft solder. If you have a good fitting joint, and you have enough brazing melted on to fill the gap, you should have a very sound joint.

I figured that, but wanted to know.

(I just posted again, because I'm having trouble with my news reader, or with my news service. Gotta check with my ISP -- although I'm afraid that if I remind them they carry newsgroups they may cancel them entirely!)

Giganews has been real crap lately. I have to log back in very couple messages.

Tim

I have had a welding friend do this for me several times.

The latest was a badly messed shank on a Silver Deming 1" drill. I cleaned up what was left of the shank in my lathe and made a close fitting sleeve that fit up to the body of the drill, as well as the remaining shank for it. My friend coated both items with brazing rod, and while hot jammed the sleeve and drill bit together. I now have a restored 1" Silver Demimg drill bit.

I am sure this has been done before and others thought it was simply a routine procedure.

Bob AZ

It was that way for a week or so. But all is well now. At least through Earthlink.

I'm using earthink and I've had to log in at least a dozen times today. Are you on dial up, DSL or broadband?

Broadband Was on Verizon FIOS in Dallas (awesome speed) bit they don't come this far out in the stick yet, so we are on cable.

What news server are you using? News.east and news.west redirect to nntp.earthlink.net.

news.west.earthlink.net but all four or five NNTP server names are redirected to the same authentication server, before connecting to Giganews. I just had to log in, once again. It was much better before they bought out Supernews.

You just HAD to screw it up again, didn't you!

(Notice I'm posting from aioe)

I had to try four times to log in this morning. :(

I just had to re-do my login also. Wonder what is wrong? That is the first time in years. ...lew...

or nearly so as the parent metal.

(...)

My understanding is that one must provide a lap surface that is some largish multiple of the material thickness. Ferinstance I would go with say, 0.5" wide lap, joining

See, for example lugged frame construction in bicycles.

Who knows? Corporate customers, like Earthlink users aren't allowed to ask Giganews what is going on. Trying to reach anyone who knows anything at Earthlink is fairly useless.

Yes, I was going off my soldering instincts, so there's about 1 square inch of area to stick some 1/8" plate onto a 1/16" wall tube.

Actually I've seen frames that are brazed with no lugs. The claim was that if you're hand brazing you can do a fillet to get all the strength you need.

(Lugs were for hairy-knuckled factory workers in England and Italy who stuck whole frames into furnaces).

I don't know if that's for real, but they were certainly the bees knees for a while back in the 1980's.

area to stick some 1/8" plate onto a 1/16" wall tube.

That sounds reasonable.

--Winston

There is special brazing rod for "fillet brazing" that has a broader "plastic range" so it doesn't all melt and run away at the same time. Generally done with gas flux too - the gas bubbles through the flux before getting to the torch. Nasty stuff, but it does a beautiful job.

Nickle silver brazing rod comes to mind. GasFlux is Methyl Borate based and you should wear cobalt blue welding lenses to better see the green flame.

I've only brazed one time, and I had very good "coaching"[1] - it was a car part where an "L" bend had opened on the inside.

When I first started to try to braze the part, I assumed that the braze metal would act something like solder, but tougher. No such luck. One of the "coaches" said, "You have to puddle the iron."

Imagine my surprise when the braze lasted the rest of the life of the car! I was amazed.

But I definitely got me doubts about "sweat-brazing," primarily because it brings to mind sweat-soldering, which is trivial to do, works, and doesn't need an OA flame, but it's only useful for electronic circuit components. (and "brazing" doesn't seem to work that way. ;-) )

Cheers! Rich