I make ornaments for friends. One of the problems with laser cutting / etching acrylic is that the bottom gets covered with soot from the cutting process. The solution is that you can leave the paper on when you laser cut, but you lose registration when it comes to engrave the backs
You also have to remove the protective paper from the top, but when you do this, the soot from the cutting / engravings that are towards the bottom of the sheet ends up on the engravings at the top of the sheet.
It is a real pain to clean.
The solution is a jig made from 1/4" MDF
Step 1: Leave the paper on -- then cut
Instead of removing the paper, cut the shape out then peel off one side or paper. When I first started doing this, I used the scrap left over from the sheet as an alignment tool.
I would but the parts back into where they were and then etch them. It solved the issue of the burning on the edges, but it still caused a lot of soot tot appear on the parts cumulatively from the bottom.
I came to the conclusion that there had to be a better way to do things.
Step 2: Laser cut the 1/4" MDF to your pattern
Instead of using the scraps that break when you look at them, I bought two (2) 2x4 sheets of 1/4" MDF.
I cut both of them to size on the panel saw.
Next, I drilled holes so that I could bolt them together with 1/4"-20 bolts and cut a recess on the bottom using a forestner bit to accommodate the nut.
Next, i created a pattern using Corel Draw were I wanted to locate the parts that will be engraved. It takes a little bit of time to cut through the MDF, but the Trotech Lasers at TechShop will do it. I also cut a 2" hole using the laser to that I can use to push the parts out without having to turn over the board.
Another benefit is that I can use this template to lay out the etching and I am sure that it hits in the right place.
To align the jig, all you have to do it to use the red-dot on the laser and make sure that the laser and the jig are at 0,0.
This makes doing multiple parts a breeze.
I made it at Tech Shop.