I just acquired a CO2 laser and have some questions

It’s a used 100W laser which the previous owner just helped me set up on Saturday. We checked and realigned the mirrors after the move.

My questions:

  1. I know that a laser beam diverges over distance and I assume that divergence results in weaker power. It would seem that the greatest distance would be in the lower right corner of the bed. Should I see a difference in burning or engraving strength in that corner? At this point I am - so I’m coming here to the ‘brain trust’ to validate my experience.
  2. the previous owner installed a milliamp meter to measure laser current. How do I calculate maximum current to the tube? I want to know the max, so I can avoid it.
  3. having used a diode laser earlier this year (Sculpfun S9), should I expect to make multiple passes with the CO2 to cut through quarter inch plywood? Obviously I still have do some experiments to gain knowledge and experience - I just thought I would start with a question to hopefully jump start that knowledge.

Thanks in advance - I’m sure I’ll be back with more questions soon…

Arden

Yes, although with proper alignment it should be minimal. Figuring out where your laser’s sweet spot lies is part of the learning process.

It should be written on a sticker on the tube, but my “60 W” OMTech has what looks like a 50 W tube with narly a hint of a maximum (or even recommended) current setting.

For a genuine 100 W tube, the table in that post suggests 28 mA.

Set up a manual pulse at 50% power, fire it into a cup of water, then read the meter after a second. Double that current and you’ll know what the power supply’s maximum current is set to. If that’s around 28 mA, then you’d want to keep the power below 70% for much of your cutting. If it’s grossly higher or lower, then there are likely other issues.

Quite the contrary: you may need to throttle that puppy down.

Cutting 6 mm plywood chugs along at 6 mm/s with about 40 W from my 60 W (claimed) tube.