Technical New to me welding process - MIG Brazing

I have the same welder as yours, the red one. Had a buddy that worked at a welding shop a long time back and they had a bunch of the older orange ones that never seemed to die. He took one home after the shop closed and its still going. The combination of mig & stick is what made it so versatile. I always wondered how well it would do for a tig source.

 

I never got the hang of starting it on sheet metal, but it’s pretty easy to run on 1/8th -up, probably me and my technique have more to do with it than the machine

 

I am going to try this process

 

That was very painful to watch!

 

Me too, I checked our little MIG we use for aluminum and we already got 100% argon.

 

I'm anxious to hear what your results and opinions are.

 

What size wire are you using? I assume something like .023, but does the brazing wire come in sizes equivalent to steel wire? I have a secondary welder that I bought for sheetmetal because I'm too lazy to switch back and forth on wire sizes ,liners,tips and rollers. When I first got the welder, birdnesting was a problem. I quickly learned that while you may get away with not changing liners on larger wire sizes, with the small .023 steel wire, having the correct liner was a must. I probably should have gotten a teflon liner. Anyway, since the brazing wire is even easier to bend than the steel wire, I have to wonder about wire size and liner selection...........

 

I use 0.035".

 

Question for them that's done it:
for autobody work like 18 ga, would 023 or 030 wire ge best? And how about the trick of using a one-size-larger tip to reduce drag/birdnesting like migging aluminum without a spoolgun?

 

Too slow on the keyboard

 

Is anyone hammer welding this soft wire or just grinding it down?

 

I also have that welder, in blue: mine's a 'Cobramatic'. (In 1975, Cobramatic made an 'outrigger' wire feed for use with an AIRCO welder. Customer demands led AIRCO to parent a line of welders with the wire spool built in. The previous AIRCO machine was a stick welder, AC and DC.)
Mine still has the original liner in it from 1978!

 

OEM's use silicon bronze wire to fill spot welded joints like where the roof panel and C-pillar meet. Basically in place of body putty. The two panels are spot welded together, the joint is welded with the silicon bronze, then ground smooth. The strength is in the spot welds, not the silicon bronze filler. I'm not a welding expert, but I do work in the welding supply industry. Silicon bronze wire is available in normal diameters, not sure about .023 because OEMs would not use that small. It is very expensive, about 5 times the price of steel wire.

 

On sheetmetal ?

I was thinking....(Danger, Will Robinson,Danger)....
When welding sheetmetal with a conventional steel wire and it becomes one with the parent sheetmetal, the builder then grinds the outside face of the weld smooth. It would seam (pun intended) that it would be a place that a crack might start some time later. I'M wondering if someone went on the backside of a weld and mig brazed over the steel weld if it wouldn't serve as a strengthening support for the joint.
Simply mig brazing the joint and grinding one side flush would seem to also result in a possible eventual crack appearing.

I'm just guessing here, but while I can see some benefits with ease of application, I do wonder about long term problems.

 

I looked at the demo video linked above. To those of you with actual experience: Are you getting the backside bead like that in the real world? If so that would eliminate any fear I might have about seam cracks.

 

Yes.

 

interesting process , but the video was really annoying ugh

 

Watch the first video.

 

Yea,the first video is the one I referred to earlier. One look at the of the first frame of the second was enough for me. Just turned it off.

The technique in the first one is a lot like the normal MIG sheet metal method, except there is no spacing between tacks. Think I'm gonna try it

 

would like to convert my 110v lincoln for this process do they offer a small spool for these units?

 

Yes.

There are spools the size of 3lb steel ones, except, because the wire is lighter, they are 2lbs.

 

Our minds working together must be quiet enough to watch where we first remembered are opinions while in conversation with the others immediate opinion that destroys ours! LOL!

 

Read up, Gimpy posted to my question about the spool rolls with a link.

 

@gimpyshotrods Gimpy, do you prime the joint and then apply filler? I've been told that filler doesn't stick well to brazing. What's your opinion and experience with that?

A friend of mine and I tried this today and it looks like we can do it pretty easily once you get the wire speed and current right.

 

This is a persistent myth. Filler and primer stick to brazing just fine. It needs to be rough enough, just like any other metal.

The brazing myth comes from guys who did a poor job cleaning the flux off of the base metal after torch brazing.

With MIG brazing there is no flux.

 

First I have ever heard of MIG brazing, but it's an interesting process. I've done a lot of TIG brazing with silicone bronze rod, though. Used to work at a place where we used it on sheetmetal bodies for a line of chillers we manufactured. Warpage was almost nil, so it was great for seams and various threaded inserts that were pressed in.

 

I tried it this weekend and liked it. it doesnt seem to work for plug welding overlap panels. i have a extra welder that i has replaced at work that i am going to use for this, so i can have one with bronze and one with steel wire.

 

Very true, lots of brazing with a torch in my past. Still have some rod and flux on my torch cart. The flux problem was and is very easy to solve. Hot water, lots of it. The flux is water soluble and washes away fairly easily with hot water and rags.