Been using the MC Etcher (90 degree) on acrylic with good results. As of late, the bit has started to stutter or vibrate as it goes across the surface, sometimes only in one direction, sometimes in all directions. Been using a .01 stepover, .015 depth, and a 60 ipm feed. I’ve tried adjusting the fee rate, DOC, and spring pressure with no change. Acrylic is fairly soft, so I can’t imagine the bit is worn out yet. Anyone seen this before or have any suggestions?
What machine are you using? If you have V-wheels, it may be time to adjust the tension of them, or replace them, depending on their condition.
If you have linear rails, I am not sure. Maybe put in a scrap piece and have it engrave squares and put your hand on the spindle and z-axis and identify what exactly is vibrating and where it stops.
I run a similar bit (since before the MC Etcher was available) and have seen this issue with some acrylic vendors where there is significant thickness variations, usually the cheap ones from Amazon that claim to be cast acrylic but still have plastic protective coatings rather than paper. This led me to a much deeper depth of cut to be able to ride thru the variation with little change for the engraved line. I set the zero of the bit with a vinyl protective sleeve cut to the length of the uncompressed bit, removing it after the measurement then use a 0.12" depth of cut to get to mid spring travel. The spring pressure and travel of my bit is likely different than the MC Etcher. I’ve also experimented with dust collection versus wet engraving with water with a drop of Dawn and a splash of isopropyl alcohol with similar good results.
If acrylic has plastic protective coating, it is most likely (almost certainly) extruded.
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This is cast acrylic (paper sided) that I get from a regional plastics distributor. The quality seems good and I haven’t had any issues with large thickness variations. I’ve never used the water with dawn and alcohol technique. I’ll give that a try. I’ll also do some more detective work like MatterHatter suggested and see if I can trace the starting point of the vibration. Will update with results. Thanks to everyone.