Cutting .020 HIPS on CNC Machine

[Brian Martin Pennsylvania]

Hello Everyone,
This is somewhat a continuation from a thread I started on Saw Creek Mill about lasers. In a nutshell I'm trying to cut 18" x 5/8" strips out of High Impact Polystyrene (HIPS) of two different thicknesses.

The first thickness is 3/16". My questions are:
1. Would I be able to use a 1/16" router bit to cut 3/16" or would I have to go larger. (I'm trying to minimize waste)

The second thickness is .020"
2. Once again could I use a 1/16" router bit.

I was advise to use a vacuum table because I am not going to leave bridges or gaps between the material. BTW these sheets come in 4' x 8' and I plan on buying a kit CNC machine or a laser cutter.

Any insight would be helpful,
-Brian

[David Warkentin]

Yes you will want a laser. And I am quite sure a 1/16" bit should cut it.

[Scott Shepherd]

I'm not sure you'd get good results with 3/16" polystyrene on a laser. It's very very "melty". I've never cut styrene that thick on the laser, but the stuff I have cut is very soft when it comes to lasering. I have cut it on the router a number of times with no issues. 1/16" bit on the .020" would work fine. It might work on the 3/16", it's hard to tell. That's a deep cut for that diameter. If you could go 3/32" or 1/8", you'd be in good shape. You can probably get it done with the 1/16", cutting 3/16" deep, but you'd be better off the next size up, in my opinion.

[Jim Underwood]

You'll want to calculate chip load very carefully. If it's melty stuff, you'll want to create chips, not fuzzzzz... Might be worth a call to your tooling supplier.

[Jerome Stanek]

I have cut .125 on my cnc using a 1/16 bit cuts very nice

[Richard Coers]

It's very difficult for a 1/16" bit to move chips out of the kerf. You'll have to crawl with the feeds to keep from breaking bits. Why not use a table saw?

[Brian Martin Pennsylvania]

A table saw actually melts the material and leaves a less desired edge. If we went larger with the bit would that move the chips out of the kerf. Would a dust collector also help remove the chips?

[Richard Coers]

Contact someone like Onsrud for the type of bit to use. I would try compressed air at the cutter more than dust collector. Also, once the kerf fills up, not dust collector will touch it. Cutting plexiglas experience for me. Too tough to get enough vacuum flow right at the cutter. Metal workers actually use a vortex chiller right at the bit. Less than $300
http://www.use-enco.com/CGI/INPDFF?PMPAGE=933&PMITEM=328-4352

[Brian Martin Pennsylvania]

Thanks. We will be checking this out.

[George Brown]

Another vortex cooler, adjustable cfm's

http://www.globalindustrial.com/g/pneumatics/air-compressors-tools/Air-Cooling/Exair-Spot-Cooling

and less than $200

[David Warkentin]

Just came back and looked at this. Why in the world did I say you will want a laser? Freudian slip?:) I'm sure I meant vacuum...

[Jerome Stanek]

If you use a pressure foot and an up cut 1/16 bit along with vacuum it should cut really good.

[Richard Coers]

If you use a pressure foot and an up cut 1/16 bit along with vacuum it should cut really good.

I'm curious on these recommendations of using the 1/16" bit. What kind of feed speeds do you guys use with them? I've never used less than 1/8" bits, and that is for profiling, not cutting. I'd think you have to be careful just touching the spoil board too hard with a 1/16 and snapping it. Not true? What about bit chatter? The 1/16 seems more like wire than a cutter to me. How deep are the flutes in a 1/16? Can't be more than 1/64 can they? That's not much clearance to pull chips through 3/16 material.