ACRYLIC, lets get a final word..

[DIY'er]

Ok i have been reading anything and everything i can get my hands on about milling acrylic. I am with I know many of you out there trying to dial in some feeds and speeds for cutting and milling acrylic.

I have seen articles in which people have cut into acrylic with feeds from everything from 30ipm to 100ipm, Along the same lines they claim there spindle speeds cover a range from 3k to 12k. I have read the formulas and used them that talk about chip loading and such.

I have been doing my own testing now for the last day and a half and i still cannot seem to find that right mix to actually get chips from the material. I first got build up on the bit, and now no build up but lots of weld back. The weld back is not bad it can be removed from the part but chipping is the goal.

Please if you have had success cutting into acrylic lend a helping hand.

I am using a two flute 3/32 straight end mill cutting a .05 depth 3/32 groove into acrylic.

Jake

[SCRAPWOTSCRAP]

I wish cutting acrylic was an exact science, but I don't think it is. Had recent success with 3/32 bit in a pocketing application, rpm was 14k, feed 50IPM. I was happy with the results. Your melt (weldback) can be manipulated by cutting in opposite direction. When you get the melt, I usually see it as an indication to lower rpm's and speed up the feed rate. When ideal combination is reached chips become powder-like. Been cuttin acrylic 7 years.....still learnin! Hang in there! Learnin aint so bad.

Laterrrrrrrrrrrrrrrr

[DIY'er]

Thanks for the reply. I am all about learning, I have been doing this routing thing for a couple months now and i love trying to figure out the best cutting conditions. This acrylic has got me though; i have been through so many combinations, I will give your suggestion a shot.

Jake

[big_mak]

Are you using HSS or carbide bits?

[Greolt]

I believe there is a big difference if it is cast or extruded as to how it cuts.

Greg

[Geof]

Originally Posted by Greolt I believe there is a big difference if it is cast or extruded as to how it cuts. Greg

With extruded it is practically impossible to prevent melting. And even if you do it is very likely that not long after making the part you will see crazing and stress cracks. With acrylic it is not really worth the effort to machine extruded, get cast.

[DIY'er]

Ok so as stated below cast vs extruded. Before the end of the work day i got some cast acrylic on the machine and sure enough i got beautiful chips with no weldback no clogging bit its was great.

I only ran a couple runs but for those who have had trouble with acrylic here is a starting point. 3 flute endmill, 8000rpm, 50ipm dont go to deep and stick with cast acrylic. Catch you guys later

Jake

[Motorcoach1]

I agree cast is best machined , extruded has layers of stress that causes warping. I have heat soaked acrylic to melting point to releave this layerd stress , In the long run it's not worth the trouble , unless it's a small part and not much machineing is needed. I have made thousands of acrylic parts. The biggest thing is heat at the cutting edge. I have allways used high pressure blast of air on the cutting edge and a little watermist with soap in it. The result every time is a great cut and good finish. the speed was not a factor useing this method but it has been the only method that has given good results everytime. the cutter bits were 2 and 3 and 4 flute and just about everycutter you can name all have the same results with this method - the name of the game is KEEP it COOL so hook up that air nozzel and get blasting. I had a deacated air pump with a small tank 12 CFM with a small pidot tube arangement for the liquild flow into the air streem.

[Claude Boudreau]

Just my 2 bits here, I have notice quite a difference in the finish when cutting different colors of acrylic sheets ,the red is a lot harder to cut cleanly than the blue for example, I think it has to do with the glass content...But I only use a small home made cnc with 1/4 inch router...

[Geof]

Originally Posted by Claude Boudreau Just my 2 bits here, I have notice quite a difference in the finish when cutting different colors of acrylic sheets ,the red is a lot harder to cut cleanly than the blue for example, I think it has to do with the glass content...But I only use a small home made cnc with 1/4 inch router...

There is no glass in acrylic.

If you are finding a difference in machining between different colours check and make sure they are both cast acrylic.

[ImanCarrot]

Totaly agree with the Cast acrylic instead of Extruded. I've been machining this stuff for years. Also agree on two flutes.

Remember CLIMB cutting all the way as opposed to Conventional.

[chuck99z28]

Where do you guys get cast acrylic?

Obviously not Home Depot.

Is there a good source for hobbists?