longjohns

I have an old schwinn Madison frame that I want to get powdercoated but it has two small dings on the top tube. Would I be able to use some brass Braze to fill the dings then file then smooth? Would it be possible to do this with a cheap mapp torch? I don't have the materials to do it because I want to be sure of the stuff I needed to get. I asked here because it was a question about brazing! Sorry if it's in the wrong place!

JohnDThompson 

I'd use lead solder -- much lower melting point and still will stay in place better than e.g. "Bondo."

longjohns

Great where can I get the stuff?

Scooper

Auto supply houses like Eastwood. It's also called "body solder"...

sannerbikes700

Also keep in mind if you don't have capabilities to braze, you can use JB Weld to fill a dent.

You can powder coat over it just fine. Make sure to hand sand the surrounding area well, and duct tape the area off for when the powder coater media blasts.

jharley

I'm new here, but just noticed your post because I am doing a similar thing. The powdercoater that I've used before told me that lead solder will melt at the temperature used for powdercoating, that whatever you use to fill has to have a melting temperature at least 60% above the temperature used for powdercoating which is usually around 400 degrees F, plus 60% gives you 640 degrees F. Lead solder melts around 400-500. He suggested silver solder, which depending on what you have melts at like 800-1100 or something. I think you can melt that with a MAPP torch.

JB weld sure sounds like a nice cheap alternative though!

black66

You still have to check the temp range for JB Weld though.. It loses its bonding props at high temps; and I suspect that will be lower than the melting point of lead solder. And its harder to see if it happened or not.

sannerbikes700

The JB works just fine under powder coat... lots of people do it.

2wheel-lee

My powdercoater also suggested JB weld for small pits.

The JB weld package I looked at said 600 degrees, but their website says 500 degrees. Both are still above 400 degrees, but I wish they could get their own published information correct.

Sixty Fiver

Silver solder could be used and a mapp torch will generate more than enough heat for this.

Silver solder is quite expensive... we build filet brazed frames and use brass for almost everything and reserve silver for lugged frames and a few smaller jobs.