Cutting .50" Acrylic

[sebago_signworks]

Hello. Let me start by saying that I am a novice at using a CNC. I have 3 4'x8' .50" Acrylic sheets to route. I do not have a vacuum table. My "plan" is to set it up so it routes all but a paper thin layer so the letters/logo wont move. Obviously I would also have it clamped/screwed down. First question, does this sound correct.. if not what? Second question, if it is correct what is the suggested bit and feed rate?

Thanks in Advance!
Devin Fahie:confused:D

[knight_toolworks]

I screw it down even with vacuum as a upcut tends to lift it off the table.
if edge quality does not have to be perfect I use a 1/8" 2 flute upcut endmill 1ips in two passes. the dust lost the letters in place.

[Xray]

Thats alot of plexi.
Not sure what you mean by "routing all except a paper thin layer" ... I can say that with plexi, slower RPM's and higher feed rates are best. Say, 6,000 spindle RPM, 200-300 IPM.

If you were to do the opposite, that would promote heat buildup, which will cause the plexi to fuse itself behind the bit, and also build up on the tip, both of which can ruin a project.
Best to do a little trial & error on a scrap piece before trying a sheet.

Screws work fine for hold down, so long as they are out of the toolpath. Of course, you'd want to pre drill holes for the screws, else you'll fracture the plexi.

[Greybarn]

We cut a fair amount of acrylic. For 1/2" we use our sharpest 1/4" dia O flute, 18,000 RPM, 1 IPS move speed. We will do a climb cut with a 0.030" offset and leave an onion skin, and then do a conventional cut all the way through. We have a vacuum table, and typically the parts are large (24" x 24") so we don't need tabs. For smaller parts we will use tabs.

[jerry_stanek]

I screw it down even with vacuum as a upcut tends to lift it off the table.
if edge quality does not have to be perfect I use a 1/8" 2 flute upcut endmill 1ips in two passes. the dust lost the letters in place.


That seems a little deep for a .125 cutter. I would be cutting this in 4 or 5 passes to get to .5 even when I use a .25 cutter I would do 2 or 3 passes.

[sebago_signworks]

Great stuff, thank you all.

[sebago_signworks]

Awesome, I cut my first sheet of .50" Acrylic today with success, thanks for all of the advice!