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Discussion Starter · #1 ·
Searched through an ass load of threads with no luck,,, need to learn to braze sheetmetal... What do i need for material?? Flux?? ?????
Never did it before, i'm a wiz with an arc & mig/tig but never learned the art of the bronze!!!!!
All input (even smart ass comments ) is welcome!!!!!!
 

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Brazing is much like soldering (only a lot stronger). Rod should be available at welding shops. Its available flux coated and bare. If you use bare you will need flux. And above all everything must be CLEAN!!!!!! Cleanliness is vital. Cannot be stressed enough. Heat depends on what you are brazing but is usually fairly low.
 

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Small torch tip, brazing rod, flux. Low gas pressure on torch for soft flame. Warm about 2 inches of the rod and dip it in the flux. Rod should be hot enough for flux to adhere to rod. Hold torch farther from metal than you would if fusion welding with torch. Heat both pieces of metal until red then touch rod in the center of heat zone. Braze will flow out. Just keep working across, dipping the rod in flux as you go.
Best to practice first on similar metal.

I personally don't like to braze sheet metal. Tends to distort the metal. Plus you can't go back and weld over or around it. Works good in certain applications. Seems to do best on sheet metal if you can do a lap joint, let the capillary action pull the braze in.
 

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Discussion Starter · #4 ·
I'm actualy going to be restoring(fixing) 2 cracks in a Cycleray headlight bucket, & figure it should be brazed, as its steal & brass anyway. I will be doing alot of practicing first, just like tig'in aluminum tubing....
I was actualy thinking of using a rounded patch metal on the inside for strength & to maintain the shape
 

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For brazing --- Run your flame just bit on the rich side In other words, get a neutral flame and then add just enough acetylene to start to get a little feather on the inner cone of the flame, it will help keep your heated area from oxidizing and help the filler flow. As has been mentioned, make sure the joint is CLEAN, and definitly a "soft" flame, you don't need to big roaring flame. Don't get your workpiece too hot, brazing takes place at a cooler temperature than welding. You'll know if your too hot, the filler will bubble and pop, instead of flowing. You'll see alot of brazed work on the old chops. Very few guys had TIG setups back then, in fact they wern't even called TIG back then. They were known as "heli-arc", back then and VERY expensive. Brazing is a great skill to have at your disposal and very versatile. Great for joining disimilar metals.

Regards,
Geo.
 

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Searched through an ass load of threads with no luck,,, need to learn to braze sheetmetal... What do i need for material?? Flux?? ?????
Never did it before, i'm a wiz with an arc & mig/tig but never learned the art of the bronze!!!!!
All input (even smart ass comments ) is welcome!!!!!!
Brazing (properly known as braze welding or bronze welding) is generally not the correct way to fabricate sheet metal (other than brass or bronze sheet). There are a few reasons it's not. First, the only types of weldment it should be used for on sheet metal parts, is the interior corner fillet weld. This weld has applications such as fuel filler necks, mounting tabs, and bungs and fittings. I like to braze fuel filler necks and bungs in.

The reason it's not suitable for sheet metal fabrications are that butt welds will crack if they're metal finished, as will exterior corner fillets. Braze welds will also crack if you attempt to control distortion with the hammer and dolly, which is often required, especially on butt welds.

Brazing on sheet metal components also subjects the part to galvanic action. This is usually not a concern on most motorcycle parts. But it can eventually corrode away the steel.

Braze welding can be very strong, in fact, you can fabricate a great frame with it if the fitting is proper. But a frame is made with fillet joins and fillet welds which are left as welded. That's not the story with sheet metal parts, which need to be metal finished prior to paint or plating.

If you want to fabricate sheet metal, learn to weld. The best process for that is either oxy-acetylene, or TIG. I think oxy-acetylene is superior for several reasons, but it requires more skill.
 

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Discussion Starter · #9 ·
So the concept is as simmilar as soldering, should i use a "internal patch" piece of steel for strength, or more to hold the braze/ fill the gap between the crack???
 

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So the concept is as simmilar as soldering, should i use a "internal patch" piece of steel for strength, or more to hold the braze/ fill the gap between the crack???
Yes, very similar to soldering. The key factor that differentiates welding from brazing and soldering is the relative melting points of the base metal and the filler rod. In welding, they're generally the same. In brazing and soldering, the melting point of the base metal is higher than the filler metal. Welding results in actual fusion of the base metal and filler since both melt at the same temperature. In soldering/brazing, since the filler metal melts before the base metal, the filler metal is combined with the base metal by capillary action rather than fusion. As to your question about an" internal patch", make your fit between the pieces correctly and you won't need it.

Bob
 
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