How to cut a clean circular hole in cork

tjb

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I have some 4" round x 1/8" pieces of cork in which I need to mill a hole in the middle. The holes will be somewhere between 1/2" and 1" round and MUST be clean looking machined cuts. Is there a tool to do such a thing, or does anyone have suggestions on how to accomplish it?

Thanks in advance.

Regards,
Terry
 
I've done this with gasket material, using a center-wheel drawing compass fitted with a knife blade instead of a pencil lead. I bought the blade years ago at a hobby supply store, but I expect an amazon or google search might turn one up...or in a pinch, one could grind a drill-bit shank or dowel pin into a sharp blade without much trouble...
 
I have used a drafting compass with a small knife blade (simiar to an Exacto blade) with mixed results It works best with a very sharp blade and multiple light cuts. Another way would be to make a gasket cutter from some suitible tubing. Sharpen the edge well and twist as you make the cut. A lot depends on the nature of the cork. A Forstner blit with the cork sandwiched between two pieces of thin plywood should also work.
 
However you proceed to cut the cork in the past ive gotten the best results by first hydrating the cork. Steam works the best but if its not possible to steam then covering with a wet cloth or spraying with water until its absorbed enough moisture to Not Crumble.

Once softened, use a 1" copper pipe to "punch" cut the hole by sharpening one side of the opening edge all the way around. I like to have the beveled edge on the I.D. of the pipe which will give you a almost perfect sized hole the shape of the pipe opening.
 
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I have cut lots of cork with an adjustable pivoting gasket cutter, they use a center pin to pivot on that fits in a hole in a backing board and use a razor type of blade held at about 45 deg to the cork. Dampening the cork is a good plan, especially if cutting thin walled washers.
 
I use cork for vintage piston-fill fountain pens, and have always used a core punch, nice and sharp with a twist to get through. The trick, for me, has always been to have twist get the punch moving and the downward force cut through. Mine are generally in the .200" ID, .250" OD range, so pretty small and thin when done. I've tried a water soak, and it didn't help.
The challenge for me has always been getting the exterior down to the right size and smoothness. Now that I have a bench grinder and a lathe, both will get their chance. I suspect the bench grinder's fine wheel will be best.
Tim
 
Just echoing the prev replies....

I needed to cut out double sided adhesive foam rings. I used an Olfa circle cutter.

If you need to cut it to a pretty accurate size, another method is sandwhich the cork in between 2 pieces of alumn (or whatever scrap you have), clamp, then machine the hole to size.


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A cork drill/punch (don't know the official name) is a very easy way to do it. Basically you can make one by sharpening the end of a piece the correct size tubing. The ones we use to use in the lab had a T handle on the unsharpened end for turning.IMG_6897.JPG
 
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