# Cutting discs out of semi-flexible plastic



## enLIGHTenment (Aug 5, 2007)

What's the easiest/cheapest way to cut a few discs out of 1mm semi-flexible plastic?

To be clear, I don't want to drill a bunch of holes where the material in the hole is waste but rather want to get a bunch of (hole-free) discs from a small plastic sheet where the rest of the sheet becomes waste.


(Please no one say 'CNC mill'.... )


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## will (Aug 5, 2007)

Try looking for wood plug cutters. These are used to cut wooden plugs, but I am pretty sure they will work on plastic. You could also try hole cutters, these have a drill bit in the center, which you can remove. This would work best in a drill press. The size listed on the hole cutter is what the hole will be, not the piece that ends up in the hole cutter.


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## TigerhawkT3 (Aug 5, 2007)

Hmm... Sounds complicated. I think you'll need a CNC mill for that. 

I think the easiest way to do it would be to get a tube or stencil in the size you want, and use an Exacto knife (or similar sharp object) to carve out the discs.


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## gadget_lover (Aug 5, 2007)

A) Cut into squares. Mount between centers on a lathe. Turn to size. Works on wood or metal lathe.

B) Use a hole punch. They can be made easily enough (for limited use).

C) Two sided tape to hold it down, exacto knife to cut it out.

D) Two sided tape to secure it, a hole saw to cut the disk.

The more tools you have, the greater the options.

Daniel


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## lukus (Aug 6, 2007)

If you have a piece of tubing the same size as the discs you want, you can just sharpen the tubing and cut the discs with it by whacking with a hammer. I've cut quite a bit of leather that way when I needed bigger holes than I had punches. Even a piece of copper tubing for plumbing works pretty well. And I just sharpen the tubing on a belt sander.


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## mahoney (Aug 6, 2007)

If the disks are not too small in diameter, tinsnips or sturdy scissors should do the trick


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## evan9162 (Aug 6, 2007)

Use a hole saw and a drill press. Remove the pilot bit from the hole saw. If you clamp things down good to prevent movement, and start very slowly, you'll end up with really good results. I use this technique to make circular PCBs and aluminium disks for heat sinks.

Your standard hole saw will produce a disk about 0.2" less than the saw diameter. So a 1" hole saw will produce an 0.8" or so disk, and a 3/4" hole saw will make a disk about 0.5-0.55"


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## DonShock (Aug 6, 2007)

You might also want to consider punches intended for making gaskets. It'll depend on how tough the plastic is and what size disc you need.
Small set
Medium set
Large set


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## Norm (Aug 7, 2007)

As Don said a Wad punch would by far be the easiest way. 
Norm


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## enLIGHTenment (Aug 8, 2007)

Thanks for all the suggestions. I'll see what I can put together. My tool collection here is rather limited.

What I'm trying to do is cut out discs from the material of a translucent plastic DVD case to make diffusers for my lights.


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## greenlight (Aug 8, 2007)

lukus said:


> If you have a piece of tubing the same size as the discs you want, you can just sharpen the tubing and cut the discs with it by whacking with a hammer. I've cut quite a bit of leather that way when I needed bigger holes than I had punches. Even a piece of copper tubing for plumbing works pretty well. And I just sharpen the tubing on a belt sander.



I like this idea. Now I have to find some holes to punch out!!


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## LED Zeppelin (Aug 8, 2007)

enLIGHTenment said:


> Thanks for all the suggestions. I'll see what I can put together. My tool collection here is rather limited.
> 
> What I'm trying to do is cut out discs from the material of a translucent plastic DVD case to make diffusers for my lights.



If it's the material like a CD case, not poly like a video tape case, it's way too brittle to whack with a tubing punch. You'll just shatter the plastic.

With that material I think the pilotless hole saw would work best, clamping the stock on a drill press table.

If you don't have a drill press, make a guide by cutting the same size hole in a piece of scrap wood. Fix the plastic to the wood somehow (clamp, screw, firmly tape), remove the pilot drill, and use the wood to steady the hole saw as you cut the plastic.

Don't get the saws that are multiple sizes on one arbor. Those have split saws and are crap. Get one that is the size you need, they might run $5-10.

If it's poly with a live hinge, then the tubing punch would work. I'd place it on a hard, flat surface when whacking or you'll deform the plastic. MDF board or an anvil would do. But I'd probably just use snips or an X-acto knife with the poly.


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## savumaki (Aug 8, 2007)

Check 'Lee Valley Tools' who are in your backyard for hole punches similar to those used for punching holes in leather; they range in size but I have seen them up to 1".
Hope this helps.

BTW- you can call Lee Valley and ask them what sizes they have, they are very obliging.


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## savumaki (Aug 8, 2007)

enLIGHTenment said:


> Thanks for all the suggestions. I'll see what I can put together. My tool collection here is rather limited.
> 
> What I'm trying to do is cut out discs from the material of a translucent plastic DVD case to make diffusers for my lights.



Missed this on my first post;
I have some WriteRight screen protectors that may be of help, basically a peel and stick sheet which can be cut to size with scissors or razor. They diffuse rather nicely.
PM me with your address and I'll send you a couple.

A search on CPF for "WriteRight" should give you more info.

Karl


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## Calamityville_Horror (Aug 23, 2007)

If you're talking about the brittle plastic CD cases, with limited tools I would probably end up scoring with a utility knife and snapping, and then filing to size.

If it's the larger, more flexible DVD cases, heck, I've cut those with a pair of sturdy scissors.


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