Sharpening hole punch bits?

[dansls1]

Does anybody have a good, inexpensive method to sharpen the bits that come with the Japanese style hole punches? I bought the cheap one, and it worked great to start, but the bits seem to have dulled - a couple very quickly and the rest as time has gone on. I've got the dremel, but I don't think just using a stone on the outside edges would necessarily do it. Any help?

[shrike]

I have the cheap one as well, and while I haven't had to sharpen mine yet it is something I've thought of.
I'm thinking that you could chuck them in a drill and touch up the outside with a stone while spinning it up. I'd worry about the edge peening over into the bore tho' so work carefully.

Before going that far you might try just smoothing the edge by sticking an awl or other pointy object in the hole and twisting gently. If the edge is just burred or peened over a little that might give it more life. That's the way the steel in you carving set works - it doesn't remove any metal, it just smooths out the wavy edge.

[Gil]

Chuck the bit in a drill. Wet a 220 grit "wet or dry" carborundum paper and sand the rotating cutting edge. Roll up a piece of the sandpaper that fits inside the barrel, wet it and lightly finish off the inside burr.

+Gil

[dansls1]

Originally Posted by Gil

Chuck the bit in a drill. Wet a 220 grit "wet or dry" carborundum paper and sand the rotating cutting edge. Roll up a piece of the sandpaper that fits inside the barrel, wet it and lightly finish off the inside burr.

+Gil

Excellent Gil! Thanks much!

[davelant]

A dremel with some of its conical grinding bits might fit in. These punches, are they sharp by virtue of a taper on the inside of the cylinder, or the outside?