I also used John Laurer’s design to make a mount for my mini laser.
What bit type and speeds are you using. I am experimenting/learning milling acrylic.
I used a 1/16” carbide bit I bought from drill bits unlimited. It came out of a set. I believe it had a fishtail end on it. The feeds were pretty slow, and my spindle speed on this machine only goes to 3000 rpm so I used that. I snapped my bit while cutting the delrin nut because the flute length was too short for the design. Also the feedrate for the delrin nut was significantly faster than the laser mount.
John Laurer who heads up the Chilipeppr website is more advanced than I and detailed and I used his design from Fusion 360 and cam specifications to mill out the laser mount. He used a 1/16” flat Kyocera bit purchased off of eBay. I, however, used HDPE rather than acrylic for the laser mount. I had extra.
I now use single flute on acrylic to reduce melting. It creates bigger chips which is important. 10k rpm at 1500mm/min for 1/8th inch end Mill.
Just more amateur CNCr learning … this is probably a DOH to those with experience…
I did a lot of research on this because I use a lot of acrylic for projects. I have some O up-cut spiral bits in my amazon cart but before I spent $30 ea I wanted some assurance this was the right direction.
So, I did some testing using my manual mill yesterday and found the same thing about single flute and plastic .
The multi flute spiral bits worked best at higher S with lower F speeds but still had way to much melting. Even at slow F values the plastic would build up on the bit and cut off the chips. It seemed that there is a place were you could optimize the multi-flute bits but is was very touchy relative to speeds.
To my surprise an old straight single flute bit I had for woodworking chipped vs melted at most S speeds and moderate F rates. In general the best S for this bit was much lower than the multi-flute(s).
I then tried the single flute straight bit on my OX and it cut the best of anything so far (see picture), with no melting, albeit slow F and S=6K RPM. This is .093 acrylic double back taped to a base.
I am concluding (as my research suggested) that the O spiral up-cut type bit is the best choice for plastic.
The other thing that struck me is that the error in my spindle speed is at play here (see posts on spindle speed control). Meaning, its more important than I thought to know what speed you are actually running vs the speed you think you set in the Gcode. Example: @ S1000 my spindle runs >6000rpm. Got to get that new controller done ;).
This article might be a good reference to start experimenting:
https://stepcraft.us/acrylic/
@sszafran
#OXSpeedsFeeds
Thanks very usefull. consistent with what I have found.