60w Redsail M500 not cutting through

[Michael Arruda]

Hello,

I have been working with my Red Sail M500. The mirrors were pretty bad, so I just replaced them with HDD platter material. Before and after the mirror swap, it seems there is less power than there should be. I try cutting through 1/8" Luan plywood and it just doesn't make it through. Settings are 100% power, 9 speed. Scorches the wood pretty well, but still doesn't cut all the way through everywhere- when you flip it over, you can see the black outline where it cut through, but not completely- there are plenty of fibers on the bottom that were not cut and must be broken to separate the pieces.

Any idea why I would be experiencing such low power output from a 60w laser? Tube or PS needs replacement, controller not sending the right fire timing, what?

Thanks,
Michael

[Ian Franks]

We just had the same problem and replaced the tube. What a difference. Feel like we are in cutting heaven now.

[George Carlson]

I think you are "Stepping over a dollar to pick up a dime". Real mirrors are not that expensive and will make quite a difference. Using old HDD material is just a hack. An interesting experiment maybe but not very effective.

[Michael Arruda]

Actually, compared to the scratched up scorched mirrors that were in the machine, the HDD mirrors are working a bit better. The only negative is that being aluminum, a 60w laser is heating them quite a bit, to the effect of the mirror mounts getting rather hot to the touch.

-Michael

[George Carlson]

I think you have answered your own question. Obviously, if the mirrors are getting hot, they're absorbing the laser energy instead of reflecting it. Three mirrors each absorbing 20% of the power would not leave much for your cutting. I have a Redsail M900, it cuts 1/4 luan at 10mm/second.

[Michael Arruda]

George,

I was just about to agree with you and buy a set of mirrors, when something occurred to me- if thermal absorption disrupts the power of the reflected beam to any great extent, why do high power, and some low power, laser systems use Cu mirrors? A solid copper slug polished up is going to be even more thermally absorptive that the same in Al. The thermal conductivity coefficient of Al is 205 while that of Cu is 401.

-Michael

[George Carlson]

It's not thermal conductivity, it's the ability of the mirror surface to reflect the laser beam. Good mirrors and polished to a flatness of 1/10 wave or better. HDD substrates are not designed to be mirrors.