How to cut a clean circular hole in cork

tjb

Terry
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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
 

Video_man

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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...
 

RJSakowski

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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.
 

Latinrascalrg1

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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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benmychree

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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.
 

tmenyc

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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
 

darkzero

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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.


20190717_181647-800x450.jpg
 

RWanke

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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
 

tjb

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Thanks for all the responses so far. I'm finishing up another project this weekend (hopefully) and will begin studying the recommendations. A punch-style thing-a-ma-jig seems to make the most sense for a first attempt, and I'm thinking of trying to operate it on the lathe a la jcp's post.

Keep the comments coming, and I'll post results (with perhaps more questions) as I proceed.

Regards,
Terry
 

brino

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and I'm thinking of trying to operate it on the lathe a la jcp's post.
I thought @jcp meant to use the lathe to make the die....not to cut the cork.
-brino
 

tjb

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I thought @jcp meant to use the lathe to make the die....not to cut the cork.
-brino
Re-reading it, you're probably right. I didn't read it quite that way. I interpreted his post as suggesting making a backing plate out of wood or some such product, mounting the cork on the backing plate and then using the tail stock to move the die into the cork - all NOT under power, of course. Several have mentioned twisting the die as it goes into the cork. It struck me that doing it this way, the chuck could be twisted very easily while the die remains stationary. The advantage I thought he may have been referring to is uniform centering among all the pieces. That's necessary because I need to make about a dozen of them.

Thanks for the clarification. I have several pieces of 1" copper about 2" long, and I had already recognized that making the die on the lathe seemed to make sense. Your clarification makes it clearer.

Regards,
Terry
 

jcp

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Re-reading it, you're probably right. I didn't read it quite that way. I interpreted his post as suggesting making a backing plate out of wood or some such product, mounting the cork on the backing plate and then using the tail stock to move the die into the cork - all NOT under power, of course. Several have mentioned twisting the die as it goes into the cork. It struck me that doing it this way, the chuck could be twisted very easily while the die remains stationary. The advantage I thought he may have been referring to is uniform centering among all the pieces. That's necessary because I need to make about a dozen of them.

Thanks for the clarification. I have several pieces of 1" copper about 2" long, and I had already recognized that making the die on the lathe seemed to make sense. Your clarification makes it clearer.

Regards,
Terry
Sounds like you're on the right track.....keep us informed how it goes.
 

brino

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Re-reading it, you're probably right. I didn't read it quite that way. I interpreted his post as suggesting making a backing plate out of wood or some such product, mounting the cork on the backing plate and then using the tail stock to move the die into the cork - all NOT under power, of course.
I NEVER meant to say it couldn't be done your way.... try it maybe you invent the revolutionary "tjb" method of gasket production.
In fact, I cannot think of a better way to guarantee ID and OD alignment, unless they were one piece.

Please do let us all know what works for you!
-brino
 
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tjb

Terry
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I NEVER meant to say it couldn't be done your way....
Yeah, I caught that. Actually, jcp's post combined with your clarification provide what seems to me to be a good strategy:
1. Make the die on the lathe which undoubtedly will produce a cleaner edge than I could accomplish with my less-than-expert ability with a file. (This step would never have hit my radar screen without your clarification. Thanks.)
2. Fabricate some form of holder for the die to mount it in the tail stock.
3. Mount the cork blank in the 3-jaw chuck (I have a mental picture of how to make the backing plate for it, but I suspect I'll modify it somewhat as I'm building it.)
4. With lathe in neutral and not under power, feed the die into the cork, twisting as necessary with the chuck.

Still have another project to finish first. To be continued...

Regards,
Terry
 

yendor

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It may sound a little crazy but I have used Brass Tubing from a hobby shop for this sort of job.

Cut it to about a 3-4" lenght.
Use a RatTail File to sharpen the edge on one end.
Insert a press fit dowel rod in the other end for the 1" you will need to adapt/turn down the dowel but then chuck it up in a drill press and it makes a nice clean hole.
The only down side is you will need to re-sharpen the cutting end frequently as brass tubing won't hold an edge long.

I've done this many times when I've had a Paper Manuals that weren't 3 - hole punched for a binder.
 

tjb

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Okay, a little slow on completing this project. It got interrupted by surgery to fuse C3 and C4 discs in my neck. Other than that, there's really not much of an excuse.

I finally finished the project, which was to make a set of coasters to match a set of hot plates made a year or so ago. After reviewing all the helpful information, I came to the conclusion I may well have been over-thinking the project. Here's a pictorial of how I approached it.

1. I had a piece of scrap 1/4" aluminum that I turned down to an 1/8" smaller diameter than the coasters. It had a hole milled in the center that was too big, so I plugged it by pressing a piece of scrap brass into it and turning it to the proper inside diameter (3/4"):
IMG_0001.jpg

2. I clamped this to a piece of scrap plywood and used it as a template to cut out the gasket material. Some of the gasket material was cork; other was automotive. Generally, I was experimenting on which I liked better and which will hold up better under use:
IMG_0002.jpg

3. I made a punch from a piece of 3/4" aluminum tubing by turning a sharp taper to the INSIDE resulting in the outside edge being clean. This piece fit very snugly into the brass hole on my template:
IMG_0003.jpg

4. Without moving the template off of the gasket/cork from step 2, I positioned the punch in the template and gave it a sharp whack with a hammer. The result was a set of perfectly shaped holes and very clean punch-out's that I have saved for some future who-knows-what project. I was anticipating I'd need to periodically sharpen the punch, but it held up for the entire project - twelve pieces in all.
IMG_0004.jpg

5. I positioned the shaped gasket/cork onto the back of the aluminum coasters I had previously made (not covered in this thread). Sandwiching the coaster and gasket together, I clamped them firmly and glued them on with black RTV.
IMG_0005.jpg IMG_0006.jpg

6. The result was a set of coasters that very nicely match my wife's hot plates. (I was looking pretty good when she saw them!) Here are top and bottom views of both - one of the coasters has a cork back; the other has an automotive gasket material back:
IMG_0014.jpg IMG_0018.jpg

P.S.: I made stands for both the hot plates and the coasters. Didn't think to take a picture of the stands by themselves, but you get the idea. That's the reason for the holes.


Thanks to all for the typically sage advice from our seasoned veterans on this project. It actually was less complicated than I imagined it was going to be.

Regards,
Terry
 

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tghsmith

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kind of late to this, but cork bores and one of of those "whatits" tools the sharpener for cork bores..
 

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RWanke

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Very nice looking coasters. Have to file that away in the attic of my head to maybe do at a later date.
 
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Latinrascalrg1

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Honestly they look like they will be Really Nice Once they are Finished! Sorry I Dont mean anything bad just that you did such a good job and where so worried about the Cork on the BOTTOM but if you would like truthful feedback I think if you take just a bit more time you could come up with a easy way to Jazz up those coasters! Maybe some sanding swirls purposefully done in a patteren of your liking or maybe chuck them back up in the lathe and add a few detail groves, etc.....
Anyway thats just my opinion and its worth Exactly what you paid for it!
 
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tjb

Terry
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Honestly they look like they will be Really Nice Once they are Finished! Sorry I Dont mean anything bad just that you did such a good job and where so worried about the Cork on the BOTTOM but if you would like truthful feedback I think if you take just a bit more time you could come up with a easy way to Jazz up those coasters! Maybe some sanding swirls purposefully done in a patteren of your liking or maybe chuck them back up in the lathe and add a few detail groves, etc.....
Anyway thats just my opinion and its worth Exactly what you paid for it!
I have what started out as a nice shiny aluminum coaster in my study. I made it from a piece of 1/4" aluminum left over from another project. I put a nice mirror finish on it, but it didn't take long for coffee cups and drink glasses to cover it with scratches that make the finish look horrible. (I'm staring at it right now.) Unfortunately, that's the nature of aluminum. Given that we intend to actually use them as coasters, I decided on a matte finish taken down to 400 grit with an orbital sander. Did that on the hot plates and wear and tear seem to blend in to the finish. Good suggestions, but I suspect they'd show unsightly signs of wear in a very short period of time.

By the way, don't know if you were referring to any picture in particular, but the coaster photo with the gasket laid next to it is NOT a finished coaster nor is it even the top side. The final sanding wasn't done until just before final assembly, and you get a better idea of the matte finish in some of the other photos.

Thanks for looking.

Regards,
Terry
 

Latinrascalrg1

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Maybe its just cause im viewing on my phone but im looking at the pic of the 2 stacks next to one another.
I was thinking something more along this type of finish. It will do a good job hiding finger prints and some defects. Im sure over the long run the surface will show signs of use but the great thing about this style of finish is its super easy to do and redo as it were..... Anyway I hear what you are saying about the difficulties of keeping them looking nice but the important then is that they get USED and I Hope you Get Great use out of them so that you wear them out completely....:)Screenshot_20190924-230647_Google.jpg
 
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