Help! Power set to high but output is low, not able to cut.

[Robin Croen]

Greetings all, I hope you can weigh in on a problem I'm having with my new-to-me machine.

I recently bought a used China red, 1400 x 900 130w, Ruida 6442 controller, laser power upgraded to a lightobject PSU by previous owner. I tested it out with the seller and it cut through 5mm ply without breaking a sweat. This was about 4 weeks ago.

Fast forward to this weekend. I'm excited to finally get this thing going after doing some tune-up work and getting my space set up. I've gone through the process of leveling the table, aligning the mirrors and focusing the beam and everything seems spot on. I've calibrated my max power using a newly-installed analogue ammeter; 60% power in the software gives me 28mA on the meter (tube specs called for 30mA max operating power and I figured I'd go a little low).

I fired up a test file from RDworks, a 20mm square on 5mm ply. The resulting "cut" was a disappointing burned outline barely deep enough to snag a fingernail. I've only tried the ply so far but based on that I don't think I'd be able to even cut 1/8" MDF. The settings were as follows:

• From RDworks, I made a cut layer with max and min power both set to 100%, which if I understand correctly means I should be getting 100% of the 60% that I set as my software max. I set the max power on the machine control panel to 60% as well, which is the max allowed to me with the current software settings.
• Speed set to 10mm/s.
• Air assist is on.
• Chiller is on and easily holding at 18C.
• When cutting, I verified that the laser was firing at my full power setting of 60% via the ammeter which held steady at 28mA during the cut.
• I verified that there was a visible purple beam inside the tube, see pics.
• I've double checked the mirror alignment and beam focus, made some tweaks to improve conditions.
• I double checked the lens orientation, its convex side is facing up and flat side is facing down towards the table.
• I cleaned all three mirrors and the lens with DNA. The mirrors have some marks and spots that I was unable to remove, see pics.

Imgur album: https://imgur.com/a/LHfwNgC

What am I missing here? This is a used tube, but considering that the machine has been run less than an hour total since it was last able to cut through 5mm ply would it really go dead on me so fast? And if it was going dead, would the ammeter still be reading my max power setting of 28mA? I'm hoping that this user error and the right settings will solve the problem.

I've spent many hours googling and combing through the forums for answers and I'm at a loss for what to try next. Thank you all in advance for your help!

[Steve Utick]

Greetings all, I hope you can weigh in on a problem I'm having with my new-to-me machine.

I recently bought a used China red, 1400 x 900 130w, Ruida 6442 controller, laser power upgraded to a lightobject PSU by previous owner. I tested it out with the seller and it cut through 5mm ply without breaking a sweat. This was about 4 weeks ago.

Fast forward to this weekend. I'm excited to finally get this thing going after doing some tune-up work and getting my space set up. I've gone through the process of leveling the table, aligning the mirrors and focusing the beam and everything seems spot on. I've calibrated my max power using a newly-installed analogue ammeter; 60% power in the software gives me 28mA on the meter (tube specs called for 30mA max operating power and I figured I'd go a little low).

I fired up a test file from RDworks, a 20mm square on 5mm ply. The resulting "cut" was a disappointing burned outline barely deep enough to snag a fingernail. I've only tried the ply so far but based on that I don't think I'd be able to even cut 1/8" MDF. The settings were as follows:

• From RDworks, I made a cut layer with max and min power both set to 100%, which if I understand correctly means I should be getting 100% of the 60% that I set as my software max. I set the max power on the machine control panel to 60% as well, which is the max allowed to me with the current software settings.
• Speed set to 10mm/s.
• Air assist is on.
• Chiller is on and easily holding at 18C.
• When cutting, I verified that the laser was firing at my full power setting of 60% via the ammeter which held steady at 28mA during the cut.
• I verified that there was a visible purple beam inside the tube, see pics.
• I've double checked the mirror alignment and beam focus, made some tweaks to improve conditions.
• I double checked the lens orientation, its convex side is facing up and flat side is facing down towards the table.
• I cleaned all three mirrors and the lens with DNA. The mirrors have some marks and spots that I was unable to remove, see pics.

Imgur album: https://imgur.com/a/LHfwNgC

What am I missing here? This is a used tube, but considering that the machine has been run less than an hour total since it was last able to cut through 5mm ply would it really go dead on me so fast? And if it was going dead, would the ammeter still be reading my max power setting of 28mA? I'm hoping that this user error and the right settings will solve the problem.

I've spent many hours googling and combing through the forums for answers and I'm at a loss for what to try next. Thank you all in advance for your help!

The mirror in your first picture looks to have a big section in the middle with the coating burned off of it, which is certainly not helping things.

[Jerome Stanek]

did you make sure your mirrors a aligned after you moved it

[Robin Croen]

did you make sure your mirrors a aligned after you moved it

Yes it’s been aligned and double checked since being moved into my shop.

[Robin Croen]

The mirror in your first picture looks to have a big section in the middle with the coating burned off of it, which is certainly not helping things.

I’m going to order a new set of mirrors, the image I posted is mirror 2 which looks the worst. Any recommendations on what to get for new mirrors?

[Bill George]

I am curious since you checked and aligned all the mirrors how did you miss the one that is burnt up? Get new ones from LightObject.

[Rich Harman]

The mirror in your first picture looks to have a big section in the middle with the coating burned off of it, which is certainly not helping things.

That looks like a reflection of the hole in the back of the machine.

[Kev Williams]

Before tearing out too many mirrors: have you done a ramp test yet? The lines of those boxes should be much thinner. Lines that thick are indicative of being severely out of focus. Or due to a very compromised mirror or lens. If your lens has a cone on it, remove it and try again.

A ramp test is where you take a long scrap of wood or plastic, set one end on the table, and raise the other end about an inch. Set your lens focus at the middle of the ramp. Assuming a 12" long ramp, draw an 11" long x 14" tall rectangle, paint it black, and set the machine to raster engrave at the lowest power you can find that will engrave, you might try 7 or 8% power, and full speed. You may have to increase or decrease power to get a good run. I ideally you'll find a 2 or 3" long section that engraves well somewhere in that 11" . The middle of that good section is your ideal focus point. Move the lens there, and make yourself a focus tool that fits between the lens and ramp...

[Bert Kemp]

I agree with Kev those lines look way to wide should be thin so Out of focus would be my first guess. Do the ramp test and see what happens. if it has auto focus rip the plunger off and toss it .

[Jerome Stanek]

Also make sure your lens is in the correct way

[Robin Croen]

For anyone still tuning in, here's an update:

I overhauled all the optics, adding new mirrors, mirror brackets, lens, and head. This being my first machine I didn't realize how truly f*cked the old mirrors were until comparing them with the new ones. It required some tinkering to get everything mounted as the new hardware was a bit bigger than the original stuff that came on the machine. I also needed to replace the dead Z motor, which I did with a stepper and driver. I might add a probe later, but I might not since many people seem to find them more trouble than they're worth. I also replaced the original "compact" X axis linear bearing carriage which was missing a lot of bearings with a standard-sized MGN12H clone, which so far seems to have taken care of some wobble issues.

Having made these changes I had a much easier time with alignment and was able to successfully make some test cuts. I also upped the cut speed to 20mm/s as I've read that 10 and under can cause some issues with laser power in the software. I haven't yet had time to find the focal length but I plan to make some gauges this weekend and continue to dial in the machine.

Thanks to all for your help