It has to be a special tint. and you NEED TO BE WEARING LASER SAFTEY GLASSES!!!
I can not stress this enough. The back scatter from the cutting beam is bright enough to damage your eyes.
Don’t risk your eyes or anyone else’s.
Get the right kind of safety glasses for your laser and wear them. Make visitors wear them.
You can also get shielding plastic to build a safety view window in a box to put over your XC.
And yes, people run the laser at very low power to focus and position it.
(jtechphotonics site went down immediately after I posted - opps did I do that?!)
FYI: It is possible to get big sheets of the proper tinted plastic, but it is kind of expensive.
My plan is to build a sold enclosure, probably of chipboard, and put in a few shielded view ports. 
We use .118" Amber TP Acrylic around two sides our Shapeoko 2. It even blocks the beam from our 6W 450nm LD.
Most Amber TP acrylic blocks around 95% around 445nm depending on maker. Most will have the specs for visible/UV transmission if you ask.
I’ll not bother, got a couple of pairs of safety glasses for myself and the wife and no one else can accidentally walk into the shop.
Angus, yes, you switch on the laser at minimum power, I do it via GCode, set focus and Z height, then run the job running at full power (where needed).
Cheers
Ian
If you buy from jtechphotonics, Jay actually tests each sheet to verify that it is up to spec. I do not know of another vendor that does this.
Have you ever had to contact jtechphotonics? I ordered a laser from them and had some trouble with my order and I cannot get a response to any of my emails or posts on their website…
Spoken to Jay a few times via email with no delays. Maybe on holiday, email problems, off sick?
I too have spoken with Jay many times. Very prompt responses and great customer service. Not getting a response seems odd.
I was able to reduce the overall size of my protection for the laser to a box around the laser itself. You may be able to create something similar. My old huge box is pictured and then my smaller set up (youtube video).
Yup, he got back to me on Monday. He was very nice and a pleasure to work with. Highly recommend.
Great idea. I would love to copy that. How did you cut the shield? Anything special?
Jay has been always available and stands behind all his products. He is one of the only vendors I know that personally tests all the protective acrylic he ships for proper laser protection.
I just used a jig saw on the sheet of acrylic. I used super glue to glue it together. I then cut out the holes in the back to match up with my mount. Eventually I figured out I needed an ability to move it up and down without having to move the z axis since I set the laser height about 3 inches above the material. I used my dremel tool to cut two slots in the back in order for the box to slide up and down on the two screws that mount the laser.
can you prevent the z-axis from moving…i have a laser on mine and have not used it as much as i would like because i cant figure out how to restrict the z-axis. any insight?
You might find this post useful: Where is the laser engraving category? - #50 by IanWatkins
Cheers
Ian
@JeremyHill How did you manage to get it so the laser turns on and off?
Depends on which grbl hex you are using. If you are using the jtech grbl 0.9g then you can use S254 (high power) and S0 (off). If you are using the 0.9j grbl then you can use S1100 (high power- perhaps even 1200) or S0 (off). I use the picengrave pro 5 for most of my work but I have also used easel (changed the z codes to the s codes) or the Inkscape Jtech extension for gcode generation. In the cases of Easel and Inkscape, I was not going for shading of any kind. It was a pure on and off (or full power and off) type of signal I was looking for.
After some experimentation with both grbl hex codes, I came up with a preference for the 0.9g version (less latency) and created two separate power control boxes - one for laser (0.9g) and one for spindle (0.9j) operations. That may not be ideal for you but it made it easier for me. I switch over the X, Y, Z connectors that I set up for each box as well as the USB cable. I leave the laser and spindle connectors in place. I have long gone away from trying to deal with the limit/homing switches as they were problematic for me.
If you use PicSender, you can save your GRBL settings and reload them. Just flash your Arduino with the GRBL version you need ie jtech laser or latest GRBL and reload your settings with PicSender. No need to swap control boxes.
to sound like a complete moron for a second…how in the world do i know which GRBL i am using? What does this even mean i am completely new to the world of CNC and would like to learn as much as possible.
the stepdown you need to use is probably more a matter of the laser being underpowered (in comparison to ‘real’ lasercutters. A 40W laser cuts through 3mm birch like butter, focus or not.
but since you have less power to work with, it makes sense to take more care in respect to focal distance in order to get the most out of what you have. It actually amazes me that you can cut 3mm ply at all with a diode laser, so imo that makes it a really useful addition to the arsenal!
