Sharpening a Patch-cutting Osborne Arch Punch?

[Rokon]

Have been cutting patches with an Osborne arch punch using a cutting board backing; however, the punches are getting dull and need sharpening.

Does anyone have a system to hand-sharpen an arch punch without screwing up the symmetry of the cutting edge? Osborne proved no help.

Do you work only on the outside bevel or do you also work the inside bevel?

 

[FishDFly]

Thanks for asking, I have often wondered how they were sharpened. Will be interesting to see the answers.

 

[Rifleman1776]

Just use a wet/dry paper on the outside. Never, never ever, sharpen the inside of the cutting tube. Doing so will change the size.

 

[Musketeer]

I have an old Osborne 3/4" arch punch I use for my Bess. I purposely enlarged the inside a very small amount to give me a bit larger than .750" inch cut to fit more snugly in the bore (the bore on mine is just a hair under .750"). Normally what I've seen suggested, though, is to sharpen the outside bevel with your method of choice, then just very lightly run around the inside with a small piece of fine sandpaper or a round ceramic "crock" stick to remove the burr. Just like sharpening a chisel or a chisel ground knife blade (which an arch punch is just a cylindrical version of) : sharpen on the bevel side, then just very lightly knock off the burr on the flat side. Like Rifleman said, you don't want to actually "sharpen" the flat side (or inside in this case).

 

[Larry (Omaha)]

Have been cutting patches with an Osborne arch punch using a cutting board backing; however, the punches are getting dull and need sharpening.

Does anyone have a system to hand-sharpen an arch punch without screwing up the symmetry of the cutting edge? Osborne proved no help.

Do you work only on the outside bevel or do you also work the inside bevel?

I just use my diamond impregnated flat plated steel sharpening stone and work the outside bevel. Rifleman said not to sharpen the inside, but I do take a circular diamond impregnated sharpener to the inside just to make sure its edge is not turned inward. When stoning the outside, the edge will roll inward a tad making a lip, that needs to be cleaned up.
Flintlocklar

 

[Tom A Hawk]

If it can be mounted in a lathe or drill press chuck, I'd spin it against a stone or other abrasive. Should make for a quick sharpening and a true edge.

 

[ZUG]

I have an old Osborne 3/4" arch punch I use for my Bess. I purposely enlarged the inside a very small amount to give me a bit larger than .750" inch cut to fit more snugly in the bore (the bore on mine is just a hair under .750"). Normally what I've seen suggested, though, is to sharpen the outside bevel with your method of choice, then just very lightly run around the inside with a small piece of fine sandpaper or a round ceramic "crock" stick to remove the burr. Just like sharpening a chisel or a chisel ground knife blade (which an arch punch is just a cylindrical version of) : sharpen on the bevel side, then just very lightly knock off the burr on the flat side. Like Rifleman said, you don't want to actually "sharpen" the flat side (or inside in this case).

This is the correct method to use on these type of punch cutters

 

[Rokon]

I have 2 questions about sharpening systems that have been proposed.

If you use wet/dry paper, do you "shoe shin" it around the bevel?

If you sue a diamond stone, how do you stroke it? Along the bevel or up and down the bevel?

As for lathe or drill presses, the Osborne punches are individually forged, so the shanks are irregular. I guess you might be able to center the punch in a lathe with a 6-jaw chuck but never in a 3-jaw drill press.

 

[Professor flintlock]

I have 2 questions about sharpening systems that have been proposed.

If you use wet/dry paper, do you "shoe shin" it around the bevel?

If you sue a diamond stone, how do you stroke it? Along the bevel or up and down the bevel?

As for lathe or drill presses, the Osborne punches are individually forged, so the shanks are irregular. I guess you might be able to center the punch in a lathe with a 6-jaw chuck but never in a 3-jaw drill press.

Have you ever tried a ground down hole saw sharpened and spun in a drill press. I usually do about 7 or 8 thicknesses of material. Drill through a piece of pexiglass ( make a hole in it it one size bigger than your sharpened hole saw) lpush down on the pexiglass to keep your material from twisting. After grinding the teeth sharpen with a file. On the drill press.Hope you can understand my method. Picked it up in an old Muzzle Blasts.

 

[user 34300]

For a similar job, converting holes saws inot patch cutters I proceed as follows. Chuck in a portable drill, rough grind on the bench grinder, refine on the belt sander, finish the edge on a sewn wheel charged with polish-o-ray.

Anything that is not moving the abrasive away from the cutting edge will be an uphill battle. The texture of the hone of the cutter will be annular rings. The rings closest he edge will weaken it and cause the keen edge to break away.

I have a few arch punches that never get used. For cutting patches in mass, the converted hole saw run in a drill press is the best I have found. I do about 8 layers of coth at a time. Staple the cloth in to a folded pad before making patches. I can make hundreds of patches in minets.

I buy hole saws at a used tool place of about a buck each.

 

[Rokon]

Can you post a picture of a "ground-down hole saw"?

 

[kje54]

Have been cutting patches with an Osborne arch punch using a cutting board backing; however, the punches are getting dull and need sharpening.

Does anyone have a system to hand-sharpen an arch punch without screwing up the symmetry of the cutting edge? Osborne proved no help.

Do you work only on the outside bevel or do you also work the inside bevel?

You could get a shaped water stone.

 

[Pukka Bundook]

You can roll them in a figure of 8 motion on an oil -stone as well. Keep turning the punch so that you do not sharpen only one part. It's easier than you'd think to keep it right.
This is the same motion used to sharpen a bevelled gouge.

 

[user 34300]

Can you post a picture of a "ground-down hole saw"?

 

[Rifleman1776]

Rifleman said not to sharpen the inside,

Yep, I sure did say that and stick with it. If you sharpen the inside you are actually enlarging the cutter at that point and your wads will be bigger than you want. And, the larger wads, after a while will not travel up the tube to be removed. Gentle honing might be OK to remove burrs or roll over but do not sharpen the inside.

 

[Rokon]

Many thanks for all your recommendations.