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Bob Rath
01-09-2011, 9:16 PM
I'm having a bit of trouble with vector cutting 1/4" acrylic (plexiglass). I'm cutting it on a vector table with a 45w Trotec. Running 100 power and .25 speed, and while it cuts, I'm still getting some flash on the bottom side. My questions:
What speed/power settings are you using (on what type of Laser)?
Do you cut it on a vector table?
Do you cut it with the paper backing removed from both sides or what?

Thanks for your help.

Larry Bratton
01-09-2011, 9:57 PM
Epilog 40 watt..6 speed, 100power, 5000 frequency, vector table, usually leave paper on one side. If cutting with paper off both sides, I elevate it off the table with some shims etc to prevent that flash back

Joe Pelonio
01-09-2011, 10:10 PM
Similar to Larry, my 45 watt Epilog will cut it at speed 8 100% power. If the bottom has to be pristine I will leave the paper on, but most of my work is letters where the back goes onto a wall
so I can leave it off. If painting the front I peel both sides, but even then flashback that shows
marks is rare. I use a vector grid and air assist at 25 psi.

Mike Null
01-10-2011, 6:05 AM
I agree with all the other answers--leave the paper on the back. I'm in the minority but I like to use two passes for this material to keep down flaming.

I have the same machine as you and the cutting table is essential for this job.

Michael Hunter
01-10-2011, 8:42 AM
For times when flashback marks are critical (i.e. MUST NOT happen), I leave the protective film on the back and also add two layers of masking tape.

Bob Rath
01-10-2011, 10:01 AM
I agree with all the other answers--leave the paper on the back. I'm in the minority but I like to use two passes for this material to keep down flaming.

I have the same machine as you and the cutting table is essential for this job.


Mike---Since you have the same machine, do you mind telling me what settings you use?

Mike Null
01-10-2011, 10:07 AM
Bob

I'm pretty good about saving my settings by material but did not save this one. I would probably be at 100 P and maybe .5 speed at 5000 hertz with air assist. As I said, I like two passes.

Scott Shepherd
01-10-2011, 11:29 AM
Get it up off the table and the flashback will go away. Put some spacers under the material, maybe 1/4" thick or so and adjust the focus to allow for those. You'll get a nice clean edge with no tick marks. If you have pieces that will fall out, try and place spacers under those pieces so it won't drop.

Frank Corker
01-10-2011, 4:09 PM
If you have ever put paper in the bottom of the laser and lasered through acrylic you will find that the beam will go way below the surface of the cutting bed, so much so that it can burn the paper on the bottom, so I wouldn't waste your time trying to find the speed where it stops just above because you won't find it. If you are getting the flashbacks off the cutting bed, raise it in the air by putting a small stack of evenly spaced pennies underneath or wooden gold peg tees underneath just to keep it above the level, it stops all the tick marks completely.