Laser cutting thick acrylic

Laser
#1

I have some thick cast acrylic scraps with lots of usable area. Some of the thicker stuff is between 0.5" - 1".

At what thickness does it become difficult to cut this with the 130W Thunder? Any recommended techniques beyond those in the following links? For some cuts I’m not concerned about maintaining the polished edge look.

Seems like the major point to getting a good cut is to adjust the focus at a distance midway into the material.

At what thickness can the Thunder make a ‘clean’ cut in a single pass. Is an acrylic cut still relatively smooth (no steps for each cut pass) if multiple passes are needed?

How much does the kerf width change as a function of depth?
If it changes, then the edges won’t be at a right angle to the face. The context is laser cutting faces of an acrylic, then gluing them together. Ideally the edges should be fully touching the face when bonding using acrylic cement.

#2

I’ll update with a little bit more information later, but at least for the multiple passes: the coordinate system is usually very exact, and as long as you don’t adjust the piece or rechange the origin, you can basically just restart the job and have it exactly line up. Further. You can actually set the passes in Lightburn, and it will treat it all as one run/go.

1 Like
#3

An issue you’ll encounter with cutting thick pieces is the lenses - I gather the Thunders are equipped with short-throw lenses rather than long-throw lenses which have less kerf on deep cuts.

I’ve done this with confidence regularly. I also sequence cuts so that the release occurs on the final pass without issue ever.

1 Like
#4

If the laser doesn’t look doable, consider using the Shakeypoo in plastics. All depends on what end result you’re after.

#5

The Shapeko for plastics in on my todo list.

I thought I saw a thread not too long ago that the plastics Shapeko was down. Is it back up (if it was down)?

#6

There’s usually 3 “default” lenses for lasers like ours, and we stock the middle one. There are both super short focus for fine detail work, and a much longer focus for deep cuts available but we do not have them readily available to my knowledge.

#7

The shapeoko 3xxl is very much up and watch for classes ! Should have some up soon .

1 Like
#8

Any time I have cut 1/2" or greater is was a struggle to get a good cut. I would recommend the shapeoko and flame polish the edge with a torch. Can get a really great look doing that, just go lightly with the torch.

#9

Keeping in mind that cast acrylic can’t be flame polished easily but extruded acrylic can.

#10

I tried this (unsuccessfully) on Big Thunder just this past weekend, using 3/8" MDF. The challenge was that the head is too close to the workpiece. I could only lower the head about 1/4" before it was essentially touching the workpiece.

#11

There’s a long focus lens for the thunder that is for thick material.

#12

Ahhhh … thanks. Where is that stored?

#13

That is a great question. @jsnowfreedman would be the one to have seen it last. I know we had them when we got the Novas.

#14

I’ve looked around, I don’t think we have a fully assembled long (or short) throw laser head sitting around. I’ve noticed lenses for such, but only those and you need more than just the lens for it to work properly.