Cutting transparent acrylic, passes and power

[Bonjour (Bo)]

@joel1

After reading some of these post, it got me wondering if I was really getting the power I was expecting.
I said I could cut 6mm acrylic at 50% power and 20mm/S. Well that 50% power setting was really like 90% of my tube 23mA. From this, I found a few issues. When I last set my power supply I did this by setting it to give 26mA at 99%. So 50% should be around 13mA, but it was 23mA, something not right. Well, I found that my Ruida is only putting out 4.7V, so the PWM is never going to integrate to 5V, or 99% of that. My LPSU uses the same input for analog control and PWM, this tells me it probably has a cheap low pass filter to change the PWM to an analog control voltage. I bet that the analog output of my Ruida controller does the same thing.

So for a while now my power control was very much not linear or anywhere close. I just readjusted my LPSU to give 13mA out when set to 50% power. This gave me just over 25mA at 99%. I can live with that, but I still want to figure out why my controller is only doing 4.7V instead or 5V.

So the reality is I cut 6mm Acrylic at 23mA and 20mm/S. I dropped to 15mm/S and was at 17mA.

So whats the point of this? There was a comment that % power is somewhat irrelevant, which is true. But you might also want to be aware of your tubes rated power vs current and what you are really getting at different power setting. In my case I discovered that something was wrong, what was wrong might explain why I have been having an issue getting grey scale engravings to work well.

Now another issue pops into my head, I need to know how fast the LSPU integrates the PWM, this will dictate an engraving speed limit, but that’s yet another issue.

I hope the OP got their answer, but there were other good thoughts in here.

Get one of these, or you’ll always be guessing: https://www.bell-laser.com/product-page/mahoney-co2-laser-power-meter-probe-0-200-watts