I’ve noticed that when I cut acrylic, it shrinks slightly, so when doing mixed media projects (e.g., wood and acrylic), I have to sand to make up the difference. Does anyone know what the shrink percentage is or if it varied between GF acrylics and other cast acrylics? I come from a 3D printing background, and having to account for shrink in plastics like ABS is well understood, but I’m not sure if that’s the same for laser cutting plastics.
Great question - I’d do a search of the forums. Someone has had to have posed that question. Assuming you meant shrinkage along the cut lines? I can’t believe it would heat up the acrylic so much the entire piece would shrink.
What you’re seeing is called kerf. It’s not shrink so much as removing width-of-laser-beam much like using a saw blade (which removes material when cutting) vs. using an exacto knife (which slices without removing matieral).
If you search the forum for “kerf compensation” you’ll see lots of tips, tools and files.
Basically, you want to test your specific material with the settings you want to use and use calipers to figure out the kerf of your machine at those settings. Then add that amount to your cut object in your design program.
Generally it stays about the same - between .005 and .008 inches - but if you’re doing exacting stuff that can be a noticeable difference. The easiest way to confirm kerf on your machine is to cut a 1" block - and then measure what you get.
There’s lots of info about perfect fits for inlay - start here and go digging!
I’ve worked with acrylic a lot and also mixed acrylic and wood…specifically insetting one of them tightly into another. I do extra testing when using PG wood with PG acrylic just because they are very different materials. This is a very small 2"x 1" test I did just yesterday. The kerf is .016" to fit these two pieces of 1/8" PG acrylic together.