1/4" Cast Acrylic: Craiglist Find

Off the honeycomb. Definitely a pain


You lucky duck! :smile: (Nightlight looks fantastic!)


There is something in the file that I missed before and it has those weird specs by the moon and a few on the angel. Couldn’t see anything in the PNG so I took it into Inkscape and did a trace. Must have been some white pixels or something funky. I cleaned it up and finished the left side of the pillow/cloud that was cut off in the drawing.


What about placing the acrylic on top of some other sacrificial material? This way the laser cuts through the acrylic but then the excess energy gets absorbed by something else?

Or maybe placing the acrylic on top of a glass plate (invisible to IR) then a sacrificial layer, might keep smoke at bay.

Edit Sorry, this was in response to @takitus post above.


You can specify a manual focus point, but it’s not very well refined yet.

Glass plates are not invisible to IR at those wavelengths; they absorb it almost 100%.


Oh that’s right… brainfart, spent too much time in the heat today and still am not thinking 100%.

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Can you take a square and set it against the edge to see whether it slopes the thickness of the edge or if the high spot is in the center of the edge and slopes inward above & below?

If it’s the former then it’s focusing on the surface. If the latter then it’s focusing in the center.

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Quick question, where did you find the night-lite base? Was it scavenged or did you find a supplier. It looks a lot like one I have that’s branded by GE, but for the life of me I can’t find a supplier anywhere. Just thought I would ask.

He has a link to the original topic of them in the post. It’s just above the picture of the one torn apart.

Goes here:


Thanks for that, as soon as I clicked on it I remembered the post. Must be Monday or something the way my brain is working :smile:

When I find a bulk supplier I’ll post it. I have GE ones and I have Intertek, Ningbo Home Automation products. I have gotten these at Menards on sale. I have one that was a garage sale find. Menards said that if I bought them in the bulk 8 packs with three lights in each pack they would give me a deal that would get them down to less than two dollars a piece. But then I’d still have the original reflector to deal with as waste. Sawmill Creek has a thread about them but the info is outdated. I’ve tried to find something in Alibaba but my search skills with them are not that great. Walmart carries something like that. At least one store in Mexico that I saw.

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I enter in the thickness of my own materials. the edge flares to the bottom. The top of the reflector edge to edge is 2.9910" on my calipers. The bottom of the reflector edge to edge 3.0005."

I’ve noted that before when I’m doing inlay with thicker materials that the top goes in easy but bottom is pretty tight. On the ring frame for the acrylic the way the pieces go together so tightly it’s best to go top into bottom for the mating pieces. They all are symetric so it’s fascinating to see the slight variations.


Yea, I even tried to contact GE with the model number of the one I had (came as a Stargate nightlight I bought at a comic-con). all I got back was a generic email saying check with our local suppliers, but everything linked was for industrial lighting, not consumer products.

Huh. That’s counter intuitive. The beam is conical to the focus point and then spread out after the focus point. That would end up with it being either wider in the center or wider at the top. Your experience suggests that the focus point is at the bottom not the top or middle.

But I’ve never actually measured top & bottom surfaces. So I’ve assumed the above, I think I need to run a test to see what happens with specific focusing at those 3 levels.

IIRC there’s some weird stuff that happens with refractive index once you get into the superheated zone with interesting incandescent gases in addition to atmosphere, so that intuitions from regular optics don’t work in simple fashion. (Haven’t done the calcs, just read people blathering about it.)


If the distance being entered into the slot is the distance from the surface of the material down into the material until the focal point is reached, and he has been entering the total thickness of the material into that slot thinking it was for material thickness, then he’s been setting the focal point at the base of the material.

Just an idea. :slight_smile:

Yeah. I think you’ve got it. When I saw your post about the 2 different settings being available in the UI I figured he was focusing on the bottom.

Which did 2 things for me - reaffirmed my faith in my understanding of the properties of the laser beam and made me think that perhaps properly focused in the center of the material he could really clean up the edges.

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If he doesnt make it all the way through, the beam will be absorbed by the walls and the indention will be conical shaped with the tip pointing downwards. If he barely cuts through the bottom it will still maintain the same shape.

It turns out I did have some Proofgrade 1/4" clear cast acrylic at the bottom of some veneer. I put it in. The focus height when I switch to manual cut reads .236". As far as I have noticed, Proofgrade focus height is the thickness of the material, unless I am totally missing something here.

Given that weren’t clear instructions about using your own materials, I was just deducing from Proofgrade settings since that is what autopopulates in the focus height when you add material thickness.


There’s nothing wrong with setting the focal point at the base, it just gives you a slightly cone-shaped kerf. It still cuts through.

I had a very brief email exchange with Rita on the focal point issue…bottom line, that is one of the things still under development (tweaking).

(The pre-releasers are getting ahead of the curve a bit, and particularly by trying to do advanced things like inlay and kerf adjusting. So we need to know and work around it for a while if we get into the advanced stuff before they finish up the tweaking.)

Not a biggie…but knowing about it might help you to adjust your next inlay to fit a little better. Try setting the focal point at halfway into the material. (I did add a note to that effect into the kerf adjustment tutorials - all 3 of them, when I realized what was happening.)