I'm confused and in need some help

[Walt Langhans]

So...

My shenhui laser has an 80watt RECI that is about 2.5 years old with a good number of hours one it, and a 18mm 50.8 focal length lens. It cuts 1/8" MDF at power 96% and 18mm Speed. It engraves MDF 30% power at 150mm speed.

My RayFine laser has a New 90watt RECI, and a 20mm 63.5 focal length lens. It cuts 1/8" MDF at 96% power at 16mm speed. It engraves MDF at 20% power and 200% speed.

I figured that the setting between the 2 machines would be different but I'm really baffled the higher watt laser cuts slower then the 80 watt, but engraves faster.

I'm assuming it has to do with the lens but that's only a guess, does anyone KNOW what's going on?

[George M. Perzel]

Hi Walt;
Also have a Shenhui with dual 80 watt RECI tubes, both running with 40mm lens.
I have found that one tube runs "hotter" than the other (appears to have more power). I have measured 80 watt RECIs at 95% power and found the one is about 92 watts and the other is about 82 watts-go figure.
Also, shorter focus lens tend to cut better because the beam is finer at the point of cut and beam dispersion is less. Type and quality of lens also make a difference.
All in all, there are many factors affecting beam performance and that is why giving precise values for power and speed for a particular material is really very iffy.
Hope that helps
Best Regards,
George
Laserarts

[Walt Langhans]

Thanks for the reply George. Every thing you said makes sense and a I get it. It's just still seems to defy logic that adjusting the setting down for engraving and then up for cutting. It's like the tube is preforming better at the lower setting than the higher ones. Oh well, I guess it is what it is. Thanks!

[Keith Winter]

Hi Walt,

I don't have a chinese laser so I hesitated to reply. But I would suspect the same things as George, lens focal length difference, lens quality, mirror quality, and alignment would all be things I'd check. Also I can confirm even for US lasers some tubes run hotter than others. For instance on my 120w tube you'd expect it to be 50% hotter than my 80w. However we got lucky and got a really hot one, it's really about 70%+- hotter than the 80 watt.