HELP! Mirrored Acrylic Charring / Burning

[Lina charbine]

Hello,

I have an Epilog Mini 40 watt machine. It has worked great however recently my clean cut lines have turned into charred burnt lines when cutting mirrored acrylic.
I have attached a couple of reference photos, the mirrored side just looks burnt on the edges.

I have contacted 413580413581my local technician however he has no idea what could be causing this.

[John Lifer]

Are you cutting from the back? if so, it is probably the problem.

[Joe Pelonio]

How thick? I cut 1/4” at speed 8 on my 45 watt. For mirror acrylic, I apply transfer tape to the front, to prevent reflection and cut with it up. Nice clean cuts every time.

[Lina charbine]

Yes cutting from the back as the acrylic also needs to be etched. Was previously cutting fine so I now can't work out what changed.

The acrylic is 1/8" thick. Cutting using a 40watt machine using the following settings (I have however played around with all of these and tried different setting combinations):
Speed:12%
Power: 80%
Freq.: 5000Hz

[Anthony S Martin]

Are you using autofocus? My father had a similar issue with his Epilog Min 24 and it turned out that autofocus was not correctly focusing. He got it back working as some gunk had built up where it didn't belong.

[Kev Williams]

If it worked before and doesn't work so good now-- is the mirror from the same supplier? If so, chances are THEIR supplier has changed the mirror coating...

One thing I do in general when cutting plastics is to run a first, and sometimes second pass at low power to penetrate the surface slightly (.02"/.5mm), then whatever power is necessary to finish the cut. This leaves a much smoother top edge than cutting full thru in one pass, which overheats the entry of the cut leaving a raised 'mushroomed' edge. If you haven't already, try it. And note if the cut is flaring up or throwing sparks-

[Joe Pelonio]

Yes cutting from the back as the acrylic also needs to be etched. Was previously cutting fine so I now can't work out what changed.

The acrylic is 1/8" thick. Cutting using a 40watt machine using the following settings (I have however played around with all of these and tried different setting combinations):
Speed:12%
Power: 80%
Freq.: 5000Hz
Try 100% power, maybe 16-20 speed. Thinking about what has changed, is your air assist psi the same? That’s one thing that can result in charring, when your pump is not blowing enough air.