How to keep 1/8" acrylic flat

[Ernie Martinez]

I'm trying engrave letters into black acrylic sheet 24 x 12. I've arranged three 11"W x 8"H signs rotated 90 degrees so the letters run sideways from bottom to top (Left to right rotated).

My problem is that the letters at the extreme left side (bottom when oriented in laser) are not coming out as white as the rest. I'm assuming it's because of slight warpage in the sheet causing a focus issue. The warpage is almost imperceptible but if I lay the cut 8 x 11 sign on a table I can see about a 1/64" gap from flat.

What do you guys do when this happens? I'm experimenting with the black sheet before I go and screw up the more expensive Rowmark sheets.

If you don't believe that this slight variation should be enough to cause a focus problem, what else could be the culprit?

[Jim Dawson]

I would say a focus problem with beam alignment may be the culprit. We always align our beam at all 4 corners of the bed.

[Tim Bateson]

Healing tacky mat. Look near the beginning of JDS Industries catalog to find them. I won't cut RowMark/IpI without it.

[Martin Boekers]

You can check how bad the warpage is my putting the manual focus tool on the disable the axis
and slide the head back and forth. Then you will have a good idea where your focus is.

[Ernie Martinez]

Turns out my laser bed wasn't level. You would think a 4 week old brand new machine would come from the factory aligned properly.

[walter hofmann]

Hi ernie
no you should check verythings especially on a new machine, starting with the whole machine - the lasertube, the Y axis and the x- axis gantry - and the laser head is in level here you should check if the head is plumb. all this can be done best with a " torpedo level".
next check with a carpenter square if the Y-axis, x-axis is square. next if the mirror's are 45 degree and the beam is center mirror every where and check if the center of all the mirrors are in the same hight. last and not least check the distance from the end of the laser tube to the first mirror it should be no more as 1 inch.
if you want you can send me a PM
walt