How To Cut Kydex

How To Machining
1

I’m going to try to cut Kydex. I have a Shapeoko 4 Pro that I have been using to cut wood on for four years and I’ve never cut any other material. Can anyone tell me good feeds and speeds for cutting it? Also I am going to be cutting very tiny holes about 7/64" and then notches on the outer part that are 1/16"… What size and what kind of bit should I be using?

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We’ve had some discussion peviously:

https://community.carbide3d.com/search?q=kydex

and as always see:

https://community.carbide3d.com/t/materialmonday-on-youtube/13092

and

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Is there a video dedicated to Kydex or is it similar to another material that there is a video for?

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See:

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So nothing on actually using the CNC to cut the Kydex then?

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Apparently not, I had assumed that @wmoy had used the machine to cut the Kydex in advance.

We’ve had some customers cutting it contact us on support (in addition to the search link above) — the general guidelines on things to avoid for cutting any plastic apply:

  • Running the RPM too fast so that friction is created at the cutting flutes
  • Running the feedrate too slow, again causing friction at the cutting flutes
  • Dull toolling, causing friction rather than a clean cut
  • Poor chip evacuation, leading to chips being recut and ultimately melting
  • A different batch of material, that doesn’t tolerate the speed/feed parameters as well
  • using a downcut tool
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Ok thank you for the information!

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The other tricky thing to look out for is workholding — if putting in holes, use them to secure through — if not, consider a vacuum, or some other technique which will keep the endmill from lifting the (flexible) material up.

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9

Kydex is very soft, so a single flute down cut bit is going to be best for cutting it.

Small carbide drill bits are great for the holes.

Here are some 0.118" bits, just 0.009" over the 7/64" (0.1094")diameter.

Here is a 0.1065" drill bit.

Here are 0.1130" drill bits.

I successfully cut leather and drilled holes in it by using the “Blue tape and CA glue” method to adhere the entire sheet to a sacrificial 1/4" plywood panel to keep it flat.

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10

Kydex has been around for many years. Back in the 80’s it was used as a liner on the insides of ambulances due to not being porous and not absorbing things that leaked out of people and easy to clean up. It is also used for holsters due to its lower melting temp and holsters can usually be made while you wait. Kydex does not like to be cut fast it will get hot and melt. I have not cut any Kydex on my CNC but I have cut a lot of 1/4" polypropylene. Use the lowest speed setting on the router and very slow feed rates.

Here is a link to a post on the 1/4 poly I cut. Plastic on edges - #6 by avetrano

If you start at the speeds on the image you can look for any melting or material rolling up on the material. you can reduce the feed speed slower if melting material is showing up on the cut edges. If no melting is showing you can increase the feed up until melting appears and then reduce down. These increases can be adjusted while the cut is in progress and will change your feed by 10% for each click on button. Drill/machine the holes at the lowest settings. Dont over feed your 1/16" bit it will break .

Hope this helps
Anthony

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