V-shaped cutting laser?

mnrec · Mar 23, 2013

Hi everyone, first time poster, but I've been lurking a bit.

I have a project where I need to engrave into plastic (acrylic, polycarbonate or PVC would work). I need to engrave a V-shaped groove (with an included angle of 90 degrees) with a width of about .002 inches. I am not sure where to start on this, as in what type of laser to look into or how to make it a V-shape. I'm assuming I'd have to use two lasers to get that shape...but then I'm not sure how to keep the beams focused to account for inconsistencies of the surface of the plastic.

Anyone have any suggestions, or maybe point me in the right direction?

Thanks!

DTR · Mar 23, 2013

Looking at what this guy built may give you a direction of where to go.

http://laserpointerforums.com/f54/mini-cnc-laser-etcher-78491.html#post1128866

mnrec · Mar 23, 2013

Thanks, I'll check that out.

One important thing I forgot to mention, I want to cut into BLACK plastic... which I, from my limited understanding, can be done with an LED instead of a CO2 laser... right?

Speedy78 · Mar 23, 2013

Black plastic can be engraved in with a regular laser diode.

daawood123 · Mar 23, 2013

I doubt you can use LED's to cut into plastic. Maybe two high power 445nm's with line lenses?

DragonSoulSong · Mar 23, 2013

I'm going to assume that, by "LED" you meant a diode laser, am I correct? In which case, yes, you could likely use a diode laser of a high enough power output to do this, in lieu of a CO2 laser. On the other hand, if you, in fact, literally meant to ask if this could be done with an LED, then my answer would have to be, most likely not.

Edit: Haha...I got ninja'd by no less than two other people...apparently I'm a very slow typer on my phone... :crackup:

mnrec · Mar 23, 2013

So with the line lenses that you speak of, would I be able to get down to .002" or better? And for engraving a V-shaped groove, would I just orient two of them at 45 degree angles?

For this project, I could have the lasers be very close to the material being engraved.

Speedy78 · Mar 23, 2013

Not sure if you would get those tolerances with a line grating. It will produce the beam it produces with out anyway to make it more or less narrow. Or I could be completely wrong on this. This is from my experiences anyways

daawood123 · Mar 23, 2013

I dont know about the inch part, but yh, it would be a simple case of aligning the 2 beams so the ends meet. It may take longer to engrave though as the power is more spread out.

mnrec · Mar 23, 2013

Any idea how much power I'd need?

daawood123 · Mar 23, 2013

I wouldnt know exactly, but two M140 diodes driven at 1.8A should do the trick. Be sure to provide plenty of cooling.

Also, try to get the same power, as if one line is more mw than the other, then your going to have depth issues.

Things · Mar 24, 2013

I'd avoid PVC at all costs, it gives off chlorine gas when lasered, which is both highly toxic and will turn almost all metal around it into rust within a couple of days. Same goes for ABS, it gives off hydrogen cyanide, the same stuff they used in gas chambers. Teflon gives off nasty fluorocarbons too.

mnrec · Mar 27, 2013

Thanks for the tips!

I'm probably going to use black acrylic sheet. How do you think the cut edges would be? I really need them to be as smooth as possible... I'd imagine the trick there would be making sure it doesn't melt too much by controlling the power and feed rate.

I'm thinking I might get a couple of the laser modules from DTR's shop to do it.

V-shaped cutting laser?

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