Sub surface engraving

[Joe Hillmann]

I was engraving a set of pool balls this morning in a CO2 and well they were running I got bored and decided to see if I could run them faster with the yag. After a little fiddling with the setting I got it to work but the engraving wasn't showing up on the surface of the ball, it was inside the surface of the ball with very little marking of the surface. I am sure that with a little experimenting I can get it to leave the outer surface untouched and a nice clear image inside.


It looks like the ball has a coating of clear resin maybe 1/16" thick covering the colored core. The clear resin is invisible to the yag and the inner core is what is getting engraved.


Does anyone here know of any other products it might be possible to do sub surface engraving on?

[Mark Conde]

Sounds very cool. It would be great to see a pic.

[matthew knott]

Have you tried clear perspex, with a short lens (that you have) you can get tiny micro cracks inside a sheet or block, they look pretty cool when the block is lit up, much like the glass sub surface engraved blocks you see in the shops. you can get glass to go a bit but there not much point as so many people have frequency doubled machines that can do 3d engraving.

[Joe Hillmann]

Mark,
I can't get a picture of it that shows up, but it looks almost as if I engraved on the ball and then put a thick clear coat over it.

Matt,
Do the cracks inside of the sheet just happen at the focal length of the laser or are they spread out? Up till now I have never tried anything that is clear in the yag because my understanding is, it is so close to visible light (almost the same distance from red as red is from violet) that anything that is visibaly clear will also be clear to the laser.

[Joe Hillmann]

Matt, I just gave it a try on a piece of 1/2 inch plexi and wow, it was quite the show to watch it. It kind of exploded but the image is kind of visible inside of it, I'll have to try it again with lower power.

[matthew knott]

low power and a few repeats and you can get an image inside the block that looks quite nice. The perspex is almost invisable to the laser but when you have so much power focused down in a tiny area it starts to heat up any imperfections. Try adjusting power and frequency and have fun !!

[AL Ursich]

I have seen the Clear Globes with a 3D image inside made with a Laser Engraver... The Theory is that it shoots 2 beams from different directions and where they meet it makes a little bubble.... I was reading about it years ago.... Expensive Equipment... It could put your 3D face inside..... So you may have happened upon the type of laser they are using.....

AL

[Joe Hillmann]

I did some playing around and got it to work, at the moment I can't think of any piratical use for it. I found a that the plexiglass really like the frequency of 10kHz and about 40 passes. If I can find my camera I will try and get a picture of it.