So I’m trying to cnc some acrylic. simple circle shape and the material keeps moving on me. I have the clamps down as tight as my fingers can turn them but it slide on me over and over. Any suggestions?
I tried reducing speed to 45 that didnt seem to help.
I was trying to figure out how to do multiple passes so as not to take such a bite in fusion 360 but i cant seem to figure that out. thoughts?
and thanks in advance
Tape? Either double-sided (if you think you’ll be able to clean it off), or masking tape on the spoiler board and the bottom of the acrylic, then use spray adhesive to stick one to the other.
Or you could rough up the part of the acrylic that’s under the clamps and see if that will make it more difficult for things to slide.
Or rig some kind of clamping solution or jig that holds the acrylic from the sides as well as above.
A vacuum table might be the best solution of all, but that’s more expensive and involved.
Place clamps on the edges of the material also.
Or print some clamps that hold both the top and the sides.
Like these:
The original is kind of large so I printed some at half size.
-S
Thank you for the replies I’m going to try those clamps. 
We always use four clamps to fix the material and the POM board does not slide. Please keep this topic updated after you use the CNC clamp by Holy1.
Als already mentioned clamps that also provide support from the side
shameless self-promotion: snapmaker-cncdogs by brvdboss - Thingiverse
I usually use them in combination with top down clamps and/or double side tape.
(Also helps to align pieces if you do multiple runs of the same object)
Thank you for sharing this model. Our application engineer has designed some similar parts. Here is an article for your reference:
