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Cutting Acrylic

Anyone here with a heavy mill have experience cutting acrylic/perspex? I have a new project in the planning, but my previous experience with this stuff has been broken bits from running feed too high, smoking bits from running feed too slow (and the shop ends up smells like a nail salon).

Anyone have experience or a copy of the G-wizard and can recommend some feeds/speeds. It’s going to be 10mm, probably using a 6mm 2 flute emd mill.

T

Hi Tim Tim; No experience with my heavy mill at this time but I cut perspex with my laser. Any reason you are looking at the 6 mm bit. This is a large area to cut and add stress to the piece. Possible a 3 mm bit would be better running at the fastest speed for the spindle. Then adjust the feed to the best cut. Send me the file that you wish to cut and I could cut it for you (If you need it in a hurry). Bill

Use cast not extruded acrylic if available. If using small emdmills try for single flute. Chip clearing is key so single flutes work well. At 6mm a double is fine, it’s the smaller ones that don’t clear well with more than one flute. We cut shallow and fast, not that that is necessarily the best method - works for us

Thanks guys.

Bill - thanks for the offer but I need to machine some pockets into the parts so the laser won’t get me out of trouble this time.

I found a useful wall chart here http://marketing.axyz.com/files/documents/OP0BK01UK03a_Cutterguide_NA.pdf which recommends 20000rpm @ around 5000mm/min up to the full cut depth.

One other painful lesson I’ve learned is that the Acrylic tends to vibrate a fair bit. I might also put some rubber offcuts under the clamps to stop them loosening mid cut.
T

Hi Tim Tim, Just a thought could you screw the Acrylic to a separate waste board and then clamp this to your table. I cut a lot of signs 485 mm long by 140 mm high. I cut 2 at a time. using this method. Saves a lot of waste and the dust shroud does not get caught on the clamps. I hope to post photos soon.

Hi Tim Tim, not sure if you still need help. though ive had good results with the heavy mill in cutting acrylic . the trick seems to be slowish feeds and fast speeds but very shallow depths. 24000rpm @ around 800mm/min @ multiple depths of 0.5mm step down i have usually used. and to save time i dont ramp in with a helix, i just use plunge. doesnt seem to effect the cut. i use fusion 360 for cad/cam. cheers

Thanks for the pointers team.

I tried screwing it down as Bill suggested and that held the material much better than the clamps in this instance.

After getting some pointers from the supplier I used a 6mm 2 flute end mill @ 4000mm/min 16000rpm, cut depth of 2mm. Cut it beautifully.

beauty! might try that my self mate.

Hi Everyone,
I feel that I have successfully cut acrylic.
My settings are as follows-
Pass Depth 3.0mm
Stepover 96%
Spindle Speed 15000rpm
Feed Rate 250mm/sec
Plunge Rate 17mm/sec.
I have also attached a couple of Photos
One is of the bit used, it is 3mm single flute and note the minor flutes which help to throw the chips out. This bit is made for acrylic.
The other photos are grabs from a little movie that I made but the site doesn’t allow me to share this. If you would like to see it I can share over dropbox. In the photos please note how the chips are thrown out and second shows the finish achieved.
I hope this info maybe helpful
Cheers
Lyle