I have not tried this on a frame, but I have had excellent success repairing dents in antique copper vases using a "snarling iron." A snarling iron is a simple metal bar that is shaped so that when one end is clamped in a vise, the other end can contact the dent from the inside of the frame. You then smack the iron (not the workpiece) with a hammer so that when it springs back, it taps the dent out from the inside. Work slowly and carefully, as the dent will be work-hardened. I simply bend mine from cold-rolled steel, then give the business end a smooth radius with a file.
Getting a snarling iron inside the top tube of a finished frame might be impossible, though, but the technique should work on head tubes top tubes prior to assembly.
You can see a snarling iron in use here
http://home.tallships.ca/
Dave Clementson
> Hello-
> Maybe some of the frame builders on this list can answer this issue. A
> friend of mine and I were looking at his dented top tube where a previous
owner
> had let the bars swing back and put a small 1 mm deep "dimple" in the
tubing.
> Its about 1 cm in diameter. Not knowing any better I told him that the way
to
> get it fixed was to use a rig that clamped on the top and some how
"smoothed"
> out the dent, with a follow up with paint and possible filler of some
sort.
> He then asked why not drill a hole in it and pull it out like they do
> with car dents? I didn't have a good answer for him.
> Can any of the frame builders or other knowledgeable folks on this
list
> share their insights of why or why not one approach is better than the
other
> and why isn't the drilled-hole pull-out-the-dent technique used more
often? Any
> and all opinions respected.
> Cheers
> Dave Anderson
> Cut Bank MT