I apologize if this has already been covered, but here goes:

This morning my Redline fell down and the top tube hit the edge of a paint can, leaving a dent about 1" long and somewhat less than 1/8" deep - not too bad, and since it's 4130 I figure it's not really going to weaken the frame very much.

Eventually, I plan to get the frame powdercoated, and I'd like to make the tube at least look a little bit better. I'm wondering how difficult it would be to fill the dent with brass and smooth it out, assuming no previous welding or brazing experience (equipment won't be too hard to come by). Good idea, or bad idea? Anything I should know or look out for?

Thanks a bunch!

If it were my bike I'd fill with bondo and use liquid type paint. If you use good paint, catalized urethane, the durability will be good so no major loss over powder.

EDIT: Maybe you could use some autobody "lead" filler? I'm not really sure what that stuff is made of but it melts at a fairly low temperature so it shouldn't hurt the metal.

thanks for the tip.

I would find a framebuilder and have them "roll" the tube.
Esentially this is done by clamping the tube between two blocks of hardwood that have a channel the size of the top tube.Then the clamp (vise) is tightened gradually while the frame is being rotated back and forth. A little more pressure, a little more twisting until the dent has been pushed back into shape.
That may make it so you don't really need filler, just add powdercoat.
If filler is still need, you'll have to ask the powdercoater what will work. I know of a "Bondo" like substance that is aluminum based. It's called "All-Metal", by who I don't know. Ask at automotive paint supply stores.
Good luck with that. Dr. D

i appreciate it!