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I may start something here but how do you feel about gas welded frames?

I don't have a decent electrical supply to my shop, just enough to run a grinder, some lights, and a radio. I dont think the circuit could handle running a welder even with everything off. But who wants to weld in the dark?

I already have the torch and tanks. Plus I feel I weld better with gas than with other welders. Not that I am a pro by any streach of the imagination. There will be a bit of practice going on.

I'm even thinking about brazing. It was the way the Brittish did it for a long time.

Thoughts, questions, smart remarks?

Josh V

The only thing that I can think of, is a problem with the amount of heat. I have an OxyAce setup as well. just haven't gotton around to starting it up to try.

I don't see why you couldn't braze up a chassis. It would probably be plenty strong.

Joints would have to be re-designed for brazing.

Oxy-acet welding, when done right, would be stronger than a typical mig weld. There are 2 basic problems. 1) it takes more talent to do oxy-acet welding and get it right, in other words, the mig is more foolproof. 2) you heat the chassis more so keeping it all straight is harder.

FWIW, race cars were gas welded for years with great success.

Joshua

A lot of the English racing frames are nickle-bronze welded, Which is like brazing but is much stronger. You do not apply as much heat and therefore you have less heat disortion, when compared to welding. Depending on the rod selected, the strength will be from 50,000 psi up to over 80,000 psi. Your tubing is only in the Mid to Upper 30,00psi. The only thing is that this type of welding you normaly use an in gas flux Vs on the rod flux and you need to have very good fitting joints. I think frames made using Nickle-bronze welding look much better and if done correctly are stronger then either MIG or gas welding. I think that would be your best option with a gas welding. google ewi, or check out your local welding supply center for more info. Dave W

What kind of change in the joint design would be required? Would brazing be any better or less suited for square tubing? One concern I have is the fillet on the side of a joint. Obviously the inside corner is well suited for a fillet? And when a piece of square tubing of the same size joins with another of the same size, the radius of the corners creates a gap on the side. I'm not sure how this will affect it. I know you want as tight of a fit as possible.

Tomarrow I will experiment with some brazing and compare with a gas weld.

Josh V

Don't go by what I say about brazed joints. Do some research yourself, but braxing is best in overlaping joints, not but joints.

Here is a brazed control arm from an GT40

http://www.racingicons.com/gt/detail09.jpg

See how the ball joint end is made? That is what is typically done for maximum strength in a braze.

Bronze welding is different than brazing. I am still investigating the process but it seems to handle joints more like fusion welding than straight brazing. Brazing also relies on capillary action to draw the braze material in while bronze welding does not.

As far as OFW welding OFW welding was used almost exclusively to produce tubular aircraft structures up into the 1940's. The preferred alloy is 4130 chromoly. 4130 doesn't respond well to TIG or MIG but it was formulated for OFW. You get the added benefit of much higher yield strength so you can use slightly smaller sections.

I will be using gas to weld up my frame as I want something that can cut as well...

Ah, the GT40. Probably THE car I would have if money were not an object. I got a ride in one when I was 16 or 17 around Road America. That spoiled me but good.

I can see what you mean by the extra piece involved in the joint, Calvin. It is along the same lines as a lug on a older bicycle frame. Back when bikes had lugged frames.

I will go to the library tomarrow to get a brazing handbook I've seen there. I guess a little knowledge is a dangerous thing.

I also just picked up some flux covered brazing rod. It doesn't have nickel in it from what I can tell. It will be used just to play with for now. When I get to the Welding store I'll get some proper nickel-bronze rod and flux.

Josh V

Why not go to Nationsrent and get a gasoline powered welder. A co-worker suggested that to me when I asked him about brazing the frame.

Or just build your own.
http://oak.cats.ohiou.edu/~weinfurt/gaswelder.html

Another place for design information would be a bicycle shop. there are plenty of bikes that are still brazed together.

I found this web site while surfing this evening.

http://7faq.com/owbase/ow.asp?NotesOnWelding

It shead a little light on things.

I stopped by my local welding store to get some nickel-bronze rod. They didn't have any and they looked at me funny when I asked for it. At first they thought I meant silver brazing rod. It seems that if it doesn't require some form of electricity they dont sell it. The counterperson did however promise to look into it.

Josh V

Here is another site on the subjectfrom ESAB.

http://www.esabna.com/EUWeb/OXY_handbook/589oxy14_1.htm

Josh V[/url]

Joshua

Contact these guys for a local distributor


Eutectic Welding Alloys
40-40 172nd St
Flushing NY