Need Mylar help

[Kathy Burton]

A couple weeks ago someone recommended Mylar for cutting stencils, which has turned out great! (The PETG I was using stank!) However, I'm having problems with a few issues:
1) The sheet wants to fly around when I turn on the fan (Penn State 1 1/2 HP) Heavy taping takes lots of time, not good for production. I removed the grid and went to the flat bed, which helped, but not enough.
2) Chaff flying around and being sucked up, and interfering with the laser beam.
3) Smoke residue on the Mylar, even at very low power settings. I'm using a clear Mylar which may be the problem, but I can't find a reasonably priced roll of the tinted or cream-colored version. Alcohol cleans it up, but I'm trying to avoid this step.
4) I'd like to cut multiple layers, but they fuse together. Is it even possible?
Lots of questions, I know, but after a week of experimenting I'm getting frustrated.

[Joe Pelonio]

Unles you have a later model Epilog with the vacuum table, this is a problem. What I have done is to place plastic screen with velcro over the
exhaust to keep things from flying out, but they may still drop down the inside edges of the machine.

What worked the best was to spray the mylar with temporary spray adhesive, artist's or the kind used for sewing. Then stick it onto something flat like posterboard and set the laser to just cut through the mylar and barely mark the board. It peels right off. Of course now you have to clean the back, but for stencils a little temporary adhesive seems like a good thing.

On my 45 watt I cut it at speed 75, power 13, frequency 500.

[Rodne Gold]

To cut multiple layers , interleave with tissue paper. I doubt you will do better than 2-3 layers. Reduce the pressure of your air assist and you can restrict your exhaust as well if things fly around. |(a foam piece wedged in the inlet - experiment with diff densities
As to the edge quality/smoke generation , try lower pulses per inch when vector cutting.
Smoke damage may be easier to wipe off if you spray the mylar with pledge first. Havent tried itnon mylar but it might work, works on other stuff and plastics. Trying to direct air assist might also help , try that too.
We use .7-.9mm styrene for stencils , cheap , cuts well etc , only drawback is that after a lot of cutting , you get like a white powder in the machine , easy to clean, The styrene stays flat generally.

[Kathy Burton]

I'm trying all of the tricks mentioned. I already reduced the force of the fan by putting a galvanized tee on the outlet so that it partially draws from room air when I'm doing stencils, and that solved the flying problem. Also turned off the air assist which helped with the chaff.

I'm going to test on styrene today and found a local supplier, which has been part of the problem with Mylar.

Thanks for the great suggestions! You're wonderful to share your expertise.

[Ed Maloney]

I seem to remember a post that someone installed a router speed controller to the blower to lower the flow as needed. I hope I remember right because I purchased one (~$12) to get around problems like you are having!

Ed

[Bill Cunningham]

I seem to remember a post that someone installed a router speed controller to the blower to lower the flow as needed. I hope I remember right because I purchased one (~$12) to get around problems like you are having!
Ed

That will work, if you have 'brushes' in your motor like the router does.. If it's a more modern induction motor, your only going to blow something.. Modern electric motors have a tendancy to become a 'converter' when you try to lower the speed .. They convert electricity into smoke :eek: