Looking for information on how to hook up the laser power supply (doing logic design now) to linuxCNC for proper PWM control and found this link: https://github.com/bjj/2x_laser
Lots of good information on how to set up laser control INCLUDING raster!
Still don't know if the PWM signal should go in the analog pin normally used by the pot or should it go in the TTL fire input.
Anyone tried one way over the other? May just add support for both...
PWM should go to the analog pin on the Laser PS input. This input on the PS is expecting analog 0 to 5VDC and determines the power level output to the laser tube based on the incoming voltage level. A 0 to 5V PWM square wave signal with 50 percent duty cycle would essentially be the same as a 2.5Vdc signal to the input pin, and thus the laser PS would be at half of its rated output power, however, this may not correlate to 50 percent of Laser Tube power depending on the combination of Laser Tube and PS used. The TTL fire input (some have H - high level, and/or L - low level inputs) is the signal that actually fires the Laser. In its basic form, if I had a momentary push button connected to the fire input, the laser would fire every time I pushed the button at a power level that corresponds to the duty cycle of my PWM input signal.
I just finished upgrading my ULS25PS to a Laser Tube and ran my first parts last night. Very happy with it.
Thanks that was the bit of information I was missing. Will wire up one IO for the PWM signal and one for the enable. Going to optoiso both since if I had to bet the laser supply will be the first to go
I just uploaded a few photos. It is a 2 position socket in which a plug will override the system when the lid is open. I have never had the plug for it, and managed to do any adjustments with the lid closed, so haven't used it. I could use a simple wire to short across them, but just haven't needed to use it at all.
Well finally have a set up update to share. Decided to go the Raspberry Pi route with PICnc hardware.
Decided to use their hardware and software stack and make a custom card optimized for laser cutters vs mills. Along the way went to a larger PIC and feature creep set in. The default part folks use can support up to 4 axis, 3 outputs, and 5 inputs. With the larger part I am laying out a card that can support up to 5 axis, 12 inputs, and 9 outputs (3 channels with PWM).
Hi, I've found this thread very interesting. I have a very similar laser cutter, works well, except for either the laser itself, the power supply or both. Where would you suggest I begin getting it up to full power again? I've seen the laser intensity vary in the middle of a cut, which makes me think power supply, but I don't have much experience with laser tubes at all.
Is your laser air or water cooled? (since you said it was similar want to make sure it has a air cooled RF laser on it)
If so have you checked the fans / airflow?
Since the laser is working but the power changes mid cut it sounds like the tube is heating up and dropping it's output.
Another easy thing to check that would cause similar issues is the mirrors. As the head travels along the mirrors will shift slightly and the beam may be riding in and out of a bad spot on the mirror.
Both of those things are easy to check so would be my first suggestion. If those both look good (or if your laser is water cooled) post back with the brand laser so I can do some searching on what setup it uses. (some the laser and tube are integrated others they are separate and even in the separate category there is LV and HV supplies. )
My ULS25PS was recently performing similar to what you are experiencing. It was manufactured in 1995, and was running on the original RF laser. Just the fact that it was still engraving after almost 20 years on the original laser was a miracle of its own. I changed it out to a liquid cooled glass tube this past year and it has been working great since. So, to this point of interest, what is the history of the Laser in your machine? If it is the original tube of similar age, it is time for replacement. If not, we'll talk more...
Yea the RF tubes are great for longevity and are regularly re-gassed and put back in service. Downside is they are 10x the cost of a HVDC (exposed glass) tubes new. My setup came without the laser head so have to start from scratch here. Wish I could find a good deal on a RF head for it but more than likely will go HVDC just due to cost and the fact it will be used infrequently (compared to what a business would do)