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I am testing out cutting cast acrylic with Easel and Carvey.
I am using the single flute upcut 1/8 bit supported in Easel with default settings for Acrylic.
I have a 5mm acrylic sheet fastened to a 2mm one with double sided tape, and I cut a inner circle 5mm deep, then a larger circle around it 1mm deep.
Finally, I cut a rectangle around the two circles 5mm deep.
The upcut bit seems to be a good match for the acrylic, and I didn’t have any problems with melting. Overall, the shape is good, but there are some obvious problems:
The spindle touchdown points for both the circles and rectangle are slightly below where the cut should be. This results in bumps at the bottom of each circle and a small piece that sticks out at one of the corners of the rectangle.
The vertical cuts of the rectangle (especially) are not even, and slant slightly. It looks like this is worst in the vertical direction, but I haven’t measured it.
(See attached images).
I also cut another 5mm sheet alone with only 4mm cuts to make sure my double-sided tape isn’t messing things up, and it turned out exactly the same.
I carved the same model from wood too, and the result is much better. Again I used Easel defaults, with the Easel-supported 2FL straight bit. There is still some unevenness with the circle, but it doesn’t have a the problem with the “bump” from the acrylic version.
Yes, it does look like something is slipping, but it is consistently cut like that all the way through.
What could cause it to slip consistently at the touchdown point for the bit? It is cut the same all the way through, so the same thing happens on every depth pass.
I was eventually able to cut acrylic reliably on the Carvey, but it was not an issue with the belts.
The default depth for Acrylic in Easel was simply too aggressive (I believe they have changed it to more reasonable values now).
I get the best results on acrylic with a 1-flute upcut endmill and going fast and shallow. I have had good luck with 80 in/min / 0.008" cut depth and 100 in/min / 0.01" cut depth.
PS: I use cast acrylic only. Extruded acrylic just melts.
Even though it didn’t solve the issue, I at least know that rates aren’t the issue. I’ll probably be posting a new thread on this one, can’t seem to figure out what is wrong with my machine.
Issue resolved, x-axis belt had to be tightened. Suggest Inventables create a step by step of how to do this (if not already created, I could only find for the y-axis though).
