Acrylic Experts - HELP

[ColdBlooded]

I am looking for some advise from the Acrylic Experts on the Forum. I will be cutting 3/16" and 1/4" Acrylic. What is the best bits you have used to get the cleanest cuts and what is your recommended RPM and cut speed. I will be doing cuts and dados. Is there a bit that can do both with "Great Results". Does anyone have a technique for getting that mirror edge you see on commercially produced items.

Thanks for the help,

Brendan

[Steve Howden]

Onsrud make O flutes specifically for acrylic.

Very good results with:
63-712 1/8in O upcut: 16k RPM, 112ipm
65-025 1/4in O upcut: 16K RPM, 160ipm

ramp in and conventional cut.

A quick scrape with a blade to finish is usually all that is needed, but if you need mirror finish a quick flash with an oxy torch on slightly reducing flame does the trick.

HTH, Steve

[MogulTx]

I like the upcut bits, but you have to be cautious with how the material is held. Upcut will pull upward on the acrylic. I bought a few downcuts on a recommendation from a supplier, and if not using Vacuum- this works well with double sided tape.

[bleeth]

Cast and extruded Acrylic will machine differently. For extruded a straight single O-flute often works better and a slower feed and speed helps. The mirror edge is accomplished 1 of three ways. Sanding with finer and finer grit paper ending with something like 400 wet (oil works better than water). Flame polishing with a propane torch. It doesn't take too long to get the knack but you would definately want to practice on scrap first. The third way is starting with sanding to get rid of the scratches and finishing with a buffer wheel and jewelers rouge.

[ColdBlooded]

Thanks for everyones input and experience. Time to go experiment with these recommended bits and cut specs. I think I will try the flame polish method first. Sanding/Polishing sounds like a long time consuming process.

[knight_toolworks]

I have never had luck with a straight or downcut and acrylic. the chips weld too much. but yes hold down is an issue with thinner plastic no matter what. the pressure foot really helps a lot with this issue. spray adhesive works ok too.

[jerry_stanek]

Cast and extruded Acrylic will machine differently. For extruded a straight single O-flute often works better and a slower feed and speed helps. The mirror edge is accomplished 1 of three ways. Sanding with finer and finer grit paper ending with something like 400 wet (oil works better than water). Flame polishing with a propane torch. It doesn't take too long to get the knack but you would definately want to practice on scrap first. The third way is starting with sanding to get rid of the scratches and finishing with a buffer wheel and jewelers rouge.


There is are other ways onsurd 75-012 bit but that is very expensive also you can scrape the edges with a sharp utility knife. I do this and follow up with the torch.