Dimension Different Depending on Cut Direction?

[munkeluvr]

Hey, all!

So I was curious if other people have experienced this.

When I’m doing kerf size and fit tests for fitting pieces together, I’ve discovered that there is a difference depending on which direction I’ve cut the pieces in. For example, say I’m trying to cut a tab and a piece that slides into it. If I cut them vertically (long ways north and south) they may fit fine, but if I just turn the pieces in the GF UI 90 degrees and cut them east to west (in the same session, same settings etc) then the fit is too tight and they won’t go together.

This may not sound like a big deal because it really is an incredibly small difference (probably less than a kerf width over a couple inches), but I’m thinking of doing larger marquetry pieces and when fitting 20 larger pieces together this could really throw a wrench into things.

Anyone else experienced this? Anyone know of any way to fix it?

Thanks in advance!

[evansd2]

It’s possible, it’s also possible that it might be material related. @geek2nurse did some attempt to quantify some of these things.

As for marquetry and inlay, I’d recommend being careful with nodes. I wrote up a thing about it:

Improving kerf adjustment on complex shapes

This is an inkscape-specific thing, but may apply elsewhere. Kerf adjustment is well-trod territory at this point, but I recently decided to see if there was anything to improve performance. The issue: when doing a “stroke-to-path” action on an irregular shape, you can sometimes see deformation of the resulting paths. The solution: add more nodes. The software is making a best-guess estimate, which you can improve with extra nodes. Illustrated: On the left, the original shape. On the righ…

It can be really helpful to get good fits.

[munkeluvr]

Hmm, I’ll have to test the node thing. I use Illustrator and have for decades and I don’t think I’ve noticed outlining strokes to cause any imperfections, but it’s good info for me to watch out for, for sure. Thank you!

As for it potentially being a material issue, that’s certainly a variable, but it does it without fail, with several different plywood sheets as well as acrylic (acrylic is when I finally felt like it wasn’t nearly as likely to be material variation). I appreciate the reply!

[evansd2]

Yeah you’re right about the acrylic, it should be really consistent. It’s possible that your beam profile isn’t circular (not sure how but misalignment might cause that), do you notice any of the other symptoms that might happen with laser misalignment, like loss of power on the right or left of the bed?