Hi I would need to laser engrave really fine text (Patent Numbers) on a cylinder steel product 40mm or so in diameter, and the engraved text only occupies 15 degrees at max. Do I need a rotary chuck, and do you guys have any recommended machines?
At 15 deg you might be able to get away without a chuck. If you are marking steel you will need a fiber laser.
You can mark steel with a typical plasma-excited CO2 laser by painting it first with cermark (or molybdenum-bearing moly lube or sulfur-bearing things like mustard; examples of both you can search for here), but to engrave it you’ll need a fiber laser or RF-excited CO2 laser. I’d choose a fiber laser.
The difference between the high and low point would be only about 0.17 mm.
If you set the focus between the high and low point, it’s off by half of that in the worst case.