Problem engraving two ply acrylic - absolute newbie

Not sure this is the right place to ask a question like this but ran into problems when trying to engrave two ply acrylic. The engraved area is very messy and the black acrylic becomes grey - any tips for what type and of settings to use for better results? Please be kind, just started trying this out!

Used these settings
Speed: 500mm/s
Power: 10% of 100w
Tried the interval and increasing focus length with slightly better but far from good results. I’ve brushed the acrylic with plastic brush but still looks similar.

The grey you’re seeing is the acrylic vapor condensing on the surface. I’ve read of people applying bar soap to the surface, which washes off cleanly, taking the condensate with it, but that doesn’t resolve the engraving portion. I’ve used with success a liquid of dish soap and water, applied with a brush while the laser makes the passes. The liquid falls into the areas of the engraving reducing (possibly eliminating) the condensate debris.

Of course, this requires that the lid protection be overridden and one should have safety glasses in place. A fine spray bottle would be better suited for your objective, I believe, allowing you to keep a distance from the rapidly moving nozzle.

Turn your air flow to a minimum. You don’t need to blow the area with as much pressure as one would for organic materials. The flow should be only the amount necessary to keep the acrylic vapor from traveling into the nozzle and fogging the mirror.

The concentration should be not so heavy as to retain the gel-like consistency of the dish soap (Dawn, of course!) but not so watery as to sheet off the surface from the airflow.

I’d gotten good results with Trolase white-on-black acrylic:

It has a protective plastic film that carries all the crud away when you peel it off.

Setting the scan interval to 0.15 mm produced better results, perhaps because it kept the beam from plowing the same territory on subsequent passes. A slightly defocused beam would let you space out the scans even further, which might reduce the overall energy enough to produce a flatter bottom surface.

That was with a 60 W laser running 14% power at 400 mm/s. I was tinkering with the scan offset, so the text on the left test piece looks a bit raggedy.

A few more pix on my blog:

I’ve had good results with fast speed/low power and very little air assist.
You want to remove just the top layer, there should be very little “tug” at your fingernail when you run it across the engraved surface.

Thank you for the answers, will try both the power/speed settings, reducing air and cleaning worth soap! Will make a new try this weekend and reconnect.

Where is the .lbrn2 file for the plant markers ? … did I miss it on your blog?

:smile_cat:

Turns out WordPress is even more fussy about uploaded files than this forum: nothing XML-ish, no matter what file suffix it might have.

Here ya go:

Plant Marker - CSV template.lbrn2 (209.6 KB)

And some of Mary’s garden plants to feed into it:

Garden Plant Tags.csv (333 Bytes)

They’re absurdly fancy for garden plant tags, no question about it, but they got a smile and that’s what counts … :gem:

Thanks…

It looks like 1/16" or is it 1/8"?

Looks almost too professional :crazy_face:


Looks dangerous and/or kinky … ?

:smile_cat:

The Trolase is dead on 1.5 mm, so call it 1/16 inch. It comes in 1/32 and 1/8 inch, too, although I shotgunned some colors rather than thicknesses:

After considerable screwing around with those markers, nearly all my mistakes cancelled out!

I was looking at the site… hence the question… :crazy_face:

:smile_cat:

I found this great walkthrough of how to laser a two ply material like this: In-Depth Training | TroLase Engraveable Plastics and Laminates - YouTube

Also, this blog has a nice guide on this type of material: Two Tone (Ply) Acrylic Settings & Tips - Danielle Wethington

In essence the tips are

  • Use the lowest amount of power possible. I ended up using 150 mm/sec, 14% of 100W, and 400 lines per inch. Tried higher speeds but got problems with my highly detailed design, that might be a problem of the laser though.
  • Limit the air assist, I turned it off completely.
  • Defocus (I did some tests and got fair results with lowering the table about 2 mm (i.e. a little more than 1/16")
  • The guy on youtube said mr magic magic eraser was great for removing the fine dust that’s still generated. The girl on the blog used gorilla tape, haven’t tried that yet. So far I’ve only tried soap, it was far from perfect but worked ok.
  • Another great tip was that if you’re making multiple signs, don’t laser all the way through. I you keep a bit you can clean all the signs all in one go, then break them off one by one, this worked great for me.

I still don’t get perfect focus but don’t know if that’s the laser being a little out of focus.

@jkwilborn based in EU so this was 1,5 mm, which is slightly thinner than 1/16".

Thank for this, I think I should look into the scan offset setting to enable running at higher speeds. Saw this on your blog which was really helpful, will try it out – thank you!

On the small scale, the offset will vary with material as well as speed, but getting Close Enough™ definitely improves the results.