MIG brazing patch panels with silica bronze

[arcticman]

I brazed in a new (used) leading edge on a 67 hood. This is the first time using the MIG welder to do brazing. this is a nice way to go for restoration work.

[Fbks_Cruiser]

That looks really good! I hadn’t heard of brazing with a mig welder. I’ll have to look into that.

[truckster]

That looks really good. Is it easier than MIG welding? I'm really good with structural stuff, but even with practice I have a hard time not blowing through sheet metal.

[rsgt]

I have heard that plastic filler does not like to stick to brass. Maybe if it is epoxy primed first. Just a thought.

[Jrainman]

I use silica bronze wire , it does take a bit to master, this type of mig wire you are not looking for a traditional steel wire bead when using this wire , If you do this, most likly you are compromising the silica bronze with to much heat, the main thing is to make sure the back of the panel has complete penatration and being such a low heat soft metal you need to have a small amount of gap when welding two sections together so the flow is even on both sides .

it has its advantages and dis advantages but when used in the right conditions it can be a excellent choice low heat , very easy to shape or grind ,and does not rust are some of its good qualitys. Also the choice in Mig machine plays a part in how good silica bronze wire reacts to your repair.

[Hammond68]

Truckster. You don't want to keep an arc going when putting in panels. Run on the hot side and just do a series of button tacks. Frames or something that will be stressed needs a continuous weld though.

[arcticman]

You are correct. It is not welding its brazing. Welding is a fusion process wereas brazing is an adhesion process. BIG difference and you dont want to confuse them.Back in the day we used tourch and rod. I've never had an issue with Bondo not stickig to bronze. The advantage I see with using a MIG is the control you have with heat and therefore less distortion. I also agree that a butt joint with a root gap to allow penitration to the back side is a good option but its not the only one as is the case with this hood. For this job I used a lab joint. As a matter of fact most of the brazing I've seen on vehicles is a lab joint. Some vehicle makers are recommending it be used when replacing QT. panels at the section with a butt joint.

[Hammond68]

I've been a Welder for 30+ years. Tubes,pipe. 100% xray jobs. Im a welding encyclopedia. You can't fill a gap with braze. Braze is the same as solder. The only difference is it happens around 800 degrees. Solder is under 400 I believe. Both are a chemical bond. If you got good with running braze wire it would have its advantages. One disadvantage is lap joints only. Can't just butt it up and go. Must be good and clean also.

[72c20customcamper]

Don't know if it's the same but body filler wouldn't stay on anything that was brazed. Of course this was with gas welding might have been the flux

[franken]

Post #8, I agree because at least compared to steel, the brazing rod/wire is very weak.
Post #9, I'd guess flux is the issue as well.
For the OP is the wire flux core?

[arcticman]

Silica Bronze wire has no flux coating. It uses shielding gas Argon.
You can do butt joints provided you have correct root gap for proper capillary action to occur on back side allowing the joint to be finished on the top side.
an example would be sectioning a quarter Panel at the roof line or sill.
If you were replacing the lower section of a door skin (patch panel) a lap joint would be best.
Silica Bronze melts at 1900 F steel around 2700 F

[tj1970cst]

I didn't know you could use a mig to braze. I'm a pretty accomplished welder, as far as diy. Even done quite a bit of brazing.
I think your repair looks excellent.

[rjs53]

Originally Posted by tj1970cst

I didn't know you could use a mig to braze. I'm a pretty accomplished welder, as far as diy. Even done quite a bit of brazing.
I think your repair looks excellent.

X's 2. I'm not a welder by trade, my dad was and alot of my friends are. I think if talking structural which he's not, yea you'd do something different. Arcticman I think it looks great and will hold for a life time.

[Jrainman]

He is not brazing, he is using a a mig wire in his mig machine ,the wire is silica bronz wire used with gas ,its not a flux core wire, what he is using it for is well suited , Why because there is much less of a chance he will distort his hood while welding with silica Bronze wire, because the heat is much less then steel wire and it also grinds and shapes very well and the weld wont rust like a steel carbon wire weld, it is not wise to but a joint, you must have a small gap between panels as I stated earlier , This type of mig welding is widly used in european car plants today, and it is the correct way to repair panels today in these cars ,this wire is not intended for structual use, but works very well for its intended use.

[72c20customcamper]

Dont want to get to into the debate but he is not welding but in fact brazing. Welding requires the melting of the base metal being joined and in most cases adding a filler. True Hammer welding uses no filler like making Damascus steel for a knife.

From what I have researched is that the silica bronze melts at around 1800 ° carbon steel 2700° . So it's a chemical bond much like solder.

I am going to by a spool and futz around with it. Looks like a good option for panel repairs.

[clay68c10]

I briefly played around with silicon bronze on a TIG. It was interesting for sure. Doesn’t take much current to get it flowing.
It is the choice of a lot of body guys in a MIG.
I can vouch that it does hammer/dolly very easily, and I’m an amateur.

[67swb72klb]

This looks like a great option as long as fillers stick to it..

[72c20customcamper]

It's not cheap . My dealer priced a 10lb spool at 98$ and in need to use 100% argon. I have 75/ 25 argon co2. And tri mix so I would need another tank.

[arcticman]

Ive been a collision repair Tech for close to 35 years never had an issue with boby filler not sticking to a repair. For restoration work you should apply a light coat of epoxy to the repair area prior to applying fillers.