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Birth of a new/old Universal 50W laser

Posted by johnoly99 
Birth of a new/old Universal 50W laser
October 19, 2012 07:12PM
Thought I'd share our fun little project we started this evening with you guys.

Here's some Pictures of the start of the project.

A friend has an old (circa 1994) Universal brand 50W laser that he used in his shop up until 2006, when the brains released the magical blue smoke. Problem was, he bought thier #2 prototype for that model, and they told him no luck with support or parts etc... for it. Sooo, he pulled it out of service and stuck it in the corner of his shop. Well, last night we had our makersapce meeting at his place, and guess what I found hiding! We popped the hood, pulled some wires and access covers, and here it is, one day later, the old brains have been removed, new RAMPS 1.4 getting wired up and we're gonna have some fun!

Hopefully, we'll have motion tomorrow morning, the X/Y axes are driven by standard NEMA 17's, and if they are DOA, we have plenty around to swap with. The machine right now has a manual Z adjuster, you would use a piece set on top of your part to laser, and crank it up until the piece was just at the lens surface (LOL), well, it already has the complete leadscrew mechanism for driving the table up/down with the handle, so off with the handle, on with another stepper. Also, origionally it had a constant speed rotary axis, but it was driven by a NEMA 17, presumably for exact speed of rotation, but it couldn't index to set positions. Well, it can now!

The only issue I can see at the moment is the laser tube (synrad 50Watt) has a BNC connector that used to plug into the origional boards, that at the other end, splits into two 1/8" audio style male connectors. I'm trying to find some docs on the tube. The only thing we found tonight was that their new tubes have a BNC connector that drives the tubes duty cycle (0-100%, so 0-255PWM). There's a solid state relay between the power supply and the laser tube's positive line, and it should do the switching fast enough right? Or, are they "arming" (lol) the laser with the relay, and firing via the BNC connector with the PWM, or is the laser powered on with the relay, and then it's interupted via pwm on the BNC connector?I'm sure I'll find something on here, but as most commercial laser equip. goes, they seem to be pretty hush about how to hack it? No fair!

If anyone knows, drop me a line on here, I'd gladly appreciate anyone's input
Re: Birth of a new/old Universal 50W laser
October 20, 2012 05:22PM
... with one of the first RF-CO2-lasers from eksma (around 1994) I had to apply 28Volts DC as power source and then a PWM-signal with TTL level (0-5Volts) for controlling the power.

Actually I have a 40W CO2-tube with a HV-source, that is controlled different ... had not the time to test it, but is planned for the next week ...

Aufruf zum Projekt "Müll-freie Meere" - [reprap.org]
Call for the project "garbage-free seas" - [reprap.org]
Re: Birth of a new/old Universal 50W laser
October 22, 2012 12:52PM
VDX, thanks, yes, I found a pdf of the exact synrad tube, and yep 5V signal running recommended 5khz signal with PWM for power. Next up is how to drive the "tickle pulse", a 2ms pulse, to ionize the tube just below firing so it can respond fast when rastering.

Got the X Y stages running this weekend, even fired up the tubes PS and tested it out. Seems it still works, so we're good there, now on to writing the gcode interpreter to use a G0 for non-fireing moves, and whn G1 is called, fire. I want to be able to adjust the DPI of the firing with Gcode, like M92 S500 would be 500 DPI, and maybe M92 P(0-255) for power, or duty cycle of the pulse.

here's a video of it working with X/Y moves

Re: Birth of a new/old Universal 50W laser
December 28, 2012 04:46PM
any progress? I have the same Laser only as a working production model that actually works great BUT my friend has a similar vintage 25w with something not quite right so this could be a great possible fix.
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