Sharpen Those Dull Rotary Punches

[MarshalWill]

All of us want our tools to be as sharp as possible so we can do our best work. One of my pet peeves is dull punches, especially rotary ones. 40 years ago, we could get new tips or a new rotary punch and even the cheapest ones would cut well by today’s standards. These days it seems to be a different story. I would buy a new one but if they were crap 30 years ago so they’re not going to be better now. I decided to sharpen the tips in the ones I have.

To use as a holder to sharpen the tips, the handle from my Tandy 3003-00 Mini Punch Set worked great. The thread size is the same as the rotary punch tips so I got to work.

To hold the tips, I chucked the handle in my hand drill.

While running the drill, I lightly touched the tips against my grey-green extra-fine grit CRATEX wheel at an oblique angle, being careful to not heat them. Also I didn’t want to take too much material off.

Then I did the same with the leather polishing wheel on my knife grinder using red jeweler’s rouge. Note that the grinder is turned around so the polishing wheel rotates upward. The tip is not digging into it.

You can tell when you have the tip sharp enough when it will not slip off your thumbnail when held at a very low angle.

I did this for all 6 tips on both of my good quality punches and when done, they all cut effortlessly, as good as any punches I’ve ever used.

If you don’t have a grinder with a CRATEX wheel and a low RPM knife grinder, get creative but don’t use a normal grinding wheel or you may wind up with tips that are too short or ground lopsided and still won’t cut right. You might be able to do the same thing by dragging the tip across a stone while turning in the drill. Then following that with a piece of leather with your polishing compound on it. I hope this gives some direction to others with the same dull rotary punches.

Edited August 16, 2023 by MarshalWill
Bum Photos

[bruce johnson]

Good tips Will!

If you don't have Cratex a good workaround is wet-dry sandpaper over a surface with a little give.  Something like a scrap of mousepad material works well. It has enough give and conforms to prevent flat spots or divots from bouncing the drill. Chucking the handle in a drill press with the belts at the lowest speed works well too and some folks find more control with that set up. I deburr my tubes with a tapered diamond file with hand twisting and buff the outside, then by hand I spin the tube into the end grain of a fresh 2x4 to wipe the final foils off the edge.  

[fredk]

Good tips and ideas from you both.

I'll need to get 'creative' to figure out how to hold the removable punches in my Tandy punches

For some sharpening I use some W&D used dry wrapped around the handle of an old artists paint brush inside the punch tube. Just lightly, not too much, not enough to enlarge the hole

[MarshalWill]

Thanks for the additional input, Bruce. That might help some who don't have a Cratex wheel. My Dremel set came with some Cratex tips in it but I don't know if one would have the control to run that against a punch tip spinning in a drill press. You'd sure have to have a good solid rest to prop against.

Fred, the tips on one of my rotary punches have a hole through the base of them. My other one has two opposing flats on the base of them which can be done with an open end wrench. The tips on my Tandy hand punch set have hexagonal bases so a box end wrench works good on a rotary punch with that type. They all seemed to be put on with some kind of thread locker so I had to take the ones with the holes off the first time with vice grips. After that, I used a thin needle awl in the hole. There might be a spanner available to fit them but I don't have one. It didn't occur to me at the time but I could have used a short piece of piano wire that would just fit through them to lever against. I'd venture to say that if your punches aren't like any of these, they are not removable and you're out of luck. I have several pairs that are like that and getting dull so they'll get tossed one of these days.

[fredk]

I notice that you did not read what I wrote. Try again

[MarshalWill]

Obviously I mis-read what you wrote. You said "I'll need to get 'creative' to figure out how to hold the removable punches in my Tandy punches" I think you mean you don't have a way to hold them to sharpen them once they're removed. That's what I used the 3003-00 set handle for. If you don't have one and can't or don't want to get one, try drilling and tapping the end of a rod or bolt so you can screw them into that. Does that answer apply to your statement?

[Satanicblood]

What was the purpose of Putting the handle into your drill? Are you running the drill simultaneously? Why use a low rpm grinder if you’re going to do that ? This method doesn’t make sense unless I’m not understanding something