Problems cutting acrylic on Carvey

Carvey
1

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 published the easel project here: Log In | Inventables

carvey-acrylic-1.jpg2467×1944 696 KB

carvey-acrylic-2.jpg2397×1971 727 KB

2

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.

carvey-wood-1.jpg3024×4032 2.28 MB

3

That circle does not look good at all. Looks to me like something is slipping.

4

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.

5

Check small screws on pulleys if there are such on the Carvey. If not tightened enough they might slip.

Note that I have an XC and no idea on how the Carvey is put together…

6

Maybe this is what I need to do? Carvey Manual: Tensioning and Replacing Belts

There is a section on “tensioning the y axis belt.”