Re: Mount a laser on a mill?
No $400 laser diode or even a $1000 one will engrave metal. I had one and it was a waste of time. It was rated at 5 watts and I was running at 4. Had nearly $500 or more invested. Do not believe the hype on eBay or from Chinese venders here. Its great at wood and paper.
So how big is the piece you need to engrave?
I have two machines right now, the Ray Fine fiber could do the job but it was over $5000. The co2 might, maybe do fiberglass for you, and it can mark metal with Cermark coating first. The LightObject 40 watt co2 was about $3k and its a first class machine. Yes, the co2 lasers have mirrors and a water cooled glass tube.
IF you want to explore the options of mounting a 3 watt diode laser to your mill then take a look at what JTech has to offer... but again no metal engraving except to burn the anodizing off aluminum. The diode machine add on will run so s l o w you can take a nap running a job.
Retired Master Electrician, HVAC/R Commercial. FLA Saturn 2 4x4 CNC Router Mach4 Kimber 1911 45ACP