Delrin cut thickenss and alternatives

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#1

So, I knew a laser cutter could cut wood and acrylic just fine and I assumed it could cut virtually any material only limited by its power. Now I discover that you can’t cut PC/PVC due to chlorine and ABS tends to melt so you don’t get clean cuts.

I’m looking for something plastic, similar to acrylic but not as brittle. So far the only thing I’ve found is Delrin, which seems to be a double-edged sword:

  • cuts ok
  • accommodating, don’t need to be too precise with tolerances
  • robust
    howerver:
  • releases formaldehyde during cut
  • very difficult to glue
  • requires more power to cut than acrylic
  • some people say it tends to catch fire during cut
  • expensive?

Having said that, I’d like to ask the GF team what’s the maximum Delrin thickness that can be cut and if there are any recommended alternative materials (a non-brittle acrylic).


Fabricate your own toothed gears
#2

What about PET? It is less brittle, not sure if you can get it in sheets, not sure about how it melts while lasered, but it is a possibility. I use it in my 3D printers all the time and it performs well in that use.


#3

You can get PET in sheets. http://www.mscdirect.com/browse/tn/Raw-Materials/Plastics/Plastic-Sheets?navid=12101803#navid=12101803+4288145687

You could also look at High density polyethylene (HDPE).

Do you mind if I ask what you are going to be using it for?


#4

Here is a good rundown on plastics and how they work in CO2 lasers.
http://www.synrad.com/synradinside/pdfs/LaserProcessingGuide_Plastics.pdf

We have been linking to this one in a bunch of places I hope they appreciate it. :slight_smile:


Uses for white polypropylene?
#5

The thing about delrin is that it wears like a rock. Strong and smooth and rigid. In my limited experience PET is softer, as is HDPE. Those two are also less rigid, which might me a problem, might not. (I printed some spring clips in PET; they work nicely). http://www.ulsinc.com/materials-library/materials/pet/ says it produces flammable vapor when laser-cut and should be watched carefully. Ditto HDPE and my personal favorite, UMHW PE (ulsinc.com’s searchable library is pretty cool, btw).

And apparently PE can’t be easily engraved, because you just get a pool of melted plastic that re-solidifies.


#6

I’ve cut 1/4" black Delrin on one of our forges here in the office. I didn’t play around much with the settings so I can’t comment on what would ultimately be possible - but certainly <= 1/4" is doable!


#7

Hackaday has you covered. My favorite is the wheels.


#8

I’ve never used UHMWPE before. I’ve used HDPE to make positive molds for silicone rubber. It worked great; machined very well and we didn’t need to use mold release to remove the parts from the mold! I’ve never laser cut it though.


#9

Thank you everybody for your comments, there’s some very good info here.

I originally learned about Delrin from those Hackaday posts, definitely worth reading, however they don’t say how much power you need.

My usage would be to cut some robot parts, boxes, mechanical stuff in general.
I need something that doesn’t break if you drop it and not too soft.
My target thickness would be 5 or 6 mm (1/4 in) so I can use small screws to join 2 pieces perpendicularly, without an L, if needed.


#10

I like those wheels. Especially because I could take and extra few minutes and cut some encoder slots.


#11

The author of those posts mostly worked with 1/8", and warns that 1/4" can vary anywhere from 1/8" to 3/8" along a single sheet. He doesn’t specify his laser power anywhere I see, except for a comment that he is in the 40-60 Watt range. So that, combined with @jared’s comment of having cut some 1/4" (on “forges in the office”… is @jared Staff who forgot to activate his title?)

But anyway, the author of the Hackaday posts made some robot type machines with the 1/8", so I would say you are pretty well set with 1/8, and occasionally doing double layer to enhance strength.


#12

Sorry for any confusion - yes, I am GF staff. And the subject is close to my heart… not everybody has a favorite plastic, but mine is Delrin.


#13

@jared you might want to put the “Staff” tag by your name. It will but a little more weight behind your comments. And it also helps us know that our comments are heard and that it was tried by the mighty GF gods. :wink:

Edit: Shoulda kept reading. You guys are sharp and already caught this.


#14

I fixed @jared’s staff tag. :slight_smile:

The gears on the rubberband drone in the video are laser cut delrin (aka acetal). That stuff is bulletproof. On my todo list is to make a ravioli roller out of it.

Inspired at least a little bit by this.


#15

Would that be possible so it imprints a Glowforge logo on one side? or makes Glowforge logo shaped ravioli?


#16

I can speak from experience on this. Delrin/acetal is a bugger to etch. it tends to puddle instead of vaporize, leaving your etch very sloppy and droopy looking.


#17

Cutting two thin layers and sticking them together may work as a pseudo-etch.

EDIT: For clarity… I mean cut ONE layer, and attach to a not cut sub layer.


#18

Unless you want a multi-layer etch with two thin cuts and one backer piece…


#19

Just a solid wheel like a pizza roller with two slightly smaller gear-shapes on either side, so the center one splits and the other two seal. Nice idea though. :slight_smile: