View Full Version : 1/4" white acrylic lithopane - shrinkage after multiple deep engravings?

Mike Lassiter
03-09-2015, 1:48 PM

Please take a look at the picture and tell me your thoughts. I did 2 sample attempts at a lithopane I am wanting to do for my wife. Pictures left out as I think they are relevant to issue. I ran multiple passes of the pictures and cut out the red vector first at the top left with the vertical length at 5" and the second one rotated 90 degrees with the 5" side to side now to limit engraving time. The red cut lines are identical at 3" x 5" only rotated and both cut out to the side or top of the sheet.

This morning I had both cut out pieces in my hand together and noticed they were not the same size. It appears they have shrank somewhat as indicated by the measurements in the picture. The one on the far left edge is shorter and the one cut from the top edge is narrower, which seems to be tied to the fact that the raster engraving was done in the direction noted on the picture. There where 5-6 passes made on each one with full power tapering down to about 25% power trying to minimize the debris that was engraved from being stuck to the engraved area. That's a different thing, but I am sort of scratching my head about this. Do you think it is normal for the acrylic to draw up from engraving in the same direction and the engraving was done? The sheet nor parts cut out were hot, but the cut outs were slightly warm when all was done. Each of these were done separately, as I made some enhancements to the one done on the right side as pictured which was perhaps 2 hours later that the first one done. This isn't exactly the end of the world kind of thing, as I suppose I could wait several hours after engraving to cut the part out, but as you can see, the sheet the parts were cut out of measures a good deal different than the parts measure with a digital caliper.