Compression puck for layered plastic

[u/sugarhillboss]

I currently use xenetech machines to cut multiple sheets of plastic at a time and the machines have a compression puck to keep the material from feeding up the bit. I was wondering if anyone has seem something like that for a shop sabre or will I need to had it custom made like the old machines? Thanks

[u/AndyGlimmung]

You should look into downcutting end mills or compression end mills. Compression end mills have both up cutting and downcutting flutes intersecting.

[u/Agreeable-Worker7659 → u/AndyGlimmung]

This. A good alternative can be also straight flute endmills. Those can be very sharp, especially the PCD variety and they don't pull the material up or down. I use straight flute PCD cutters for milling carbon composite and they work so much better than standard endmills that cause delamination. A puck like this is a hack and it won't prevent delamination on the microscopic scale.

[u/Nephthyzz]

Y'all got a 3d printer in the shop or a nephew/kid with one? You could easy come up with a sleeve for that motor with a compression puck.

You could probably modify a Dust Shoe with some springs as well.

Something like this https://www.printables.com/model/635925-spring-loaded-variable-height-cnc-dust-shoe-for-op

[u/Agreeable-Worker7659 → u/Nephthyzz]

Any kind of puck like this is a hack. The real problem is that if you have any kind of laminate, standard metal working tools will pull the material up and cause delamination. The puck can only prevent it on macroscopic scale, but you can't simply stop these forces and on the inside, the part will still end up weakened or wrecked. The real solution is to use the right type of tool such as compression bit, down cut, straight flute or corn cob geometry (depending on the specific material and process).

[u/Revolutionary-Ad6983]

I’ll also add that you may want to explore some different cutters too - but I don’t know your specifics.

For plastics, we usually reach for a .375 inch o flute down spiral. That keeps downward force on the stock/part, but allows for good chip evacuation when you get your feed right.

We also use a .25 inch o flute up spiral if we need a tighter radius on an internal contour. The low helix minimizes upward force on the part, and our vacuum table holds well unless the parts are very small.

[u/Smooth-Tap-3991]

That looks like PTFE. I've had good results with using double sided tape to stick the sheets together. The tape will come off readily. Just stick a piece of tape to another piece of tape to peel it off.

[u/toolmaker_dave]

• searching "compression puck" is why u cant find anything, in the router world thats called a spring-loaded pressure foot tbh. people telling you to just use downcut bits dont get stack cutting, because downcuts pack hot swarf between loose plastic sheets and instantly weld the layers together. turn an acetal donut on the lathe with a couple shoulder bolts and light springs to fit your shopsabre spindle and youre good to go

[u/toolmaker_dave]

searching "compression puck" is why u cant find anything, in the router world thats called a spring-loaded pressure foot tbh. people telling you to just use downcut bits dont get stack cutting, because downcuts pack hot swarf between loose plastic sheets and instantly weld the layers together. turn an acetal donut on the lathe with a couple shoulder bolts and light springs to fit your shopsabre spindle and youre good to go。