Grounding Issues

[zeitgeist]

I just got my upgrade hardware installed on my K40 and everything seems to be working well except that I can't track down where I'm leaking voltage at. Somewhere I'm losing power between the laser PSU and the tube itself that's causing the laser to not only cut more weakly but is causing a charge to build up on the machine.

I've grounded everything I can think to ground: the plug, the chassis, the PSU case, and the case of the DSP controller, plus obviously all the ground terminals on the hardware. I even have a redundant ground line set up from the screw on the chassis to the ground of the wall plug.

For my red laser cable from the PSU I twisted it together with the laser cable itself, then double-sealed in shrink wrap, and stuffed the whole thing into vinyl tubing then capped with silicone.

I also turned off all the lights and watched to see if I could visibly detect a discharge, but no such luck.

At first I thought maybe my ground wires were too thin or I had a weak ground, but my tube is most definitely not cutting as strong as it was prior to this issue arising. Which to me suggests that I'm actively losing current rather than merely collecting ambient static, which would not be fixed by grounding directly to a metal stake or using thicker gauge wire.

I'm largely out of ideas, please help!

[zeitgeist]

I re-wried the laser tube several times, using several different sealing techniques, moved the wires all around and far away from each other, re-zip tied the wires both positive and negative to the laser tube, arranging them away from each other, checked the ground on the laser PSU, checked the other grounds as well, did multiple corona tests, and now the problem is....worse.

What else can I even do?!? The laser's completely unusable until I figure out how to fix this. Right now I can't even fire the test-laser button.

[zeitgeist]

After some more digging and talking with Marco, I discovered my LPSU was set to 220V rather than 110V and there was a crack in the silicone seal at the positive power input to the laser tube. But even after switching the LPSU to the proper voltage IN and re-connecting the power to the laser tube I'm still not getting proper performance from the machine.

At first I was only getting a maximum of 6 mA coming through the laser as measured by an analog ammeter, even when running at 80% from the software with PPI turned off. Now after making the changes to the voltage selection and reconnecting the laser, I'm able to get up to about 15 mA, but the laser does not seem to be performing correctly I'm getting tics from my stepper motors.

For example, even after aligning the optics, if I try to cut a square out of basic cardstock at 30 mm/s, 500 PPI, 50% power, it barely makes it through at all. If I engrave an image, even at 1000 PPI, 60% power, 200 mm/s I don't get a very dark and certainly not deep engraving. One of the pictures below shows the same image on a single-pass engraving. The left image is the 800 PPI, 60%, 200 mm/s. The image on the right is 500 PPI, 50% power, 300 mm/s.

But I'm also getting tics from my stepper motors where they jog one step when they're not supposed to. I included a photo below of what it looks like when they try to cut a rectangle. There is also sporadic resetting of the LCD.

I also included photos of my general arrangement of wires inside the machine and how everything is connected. I followed the wiring diagram supplied in the forums, and didn't really improvise anything. The only exceptions are that I used RGB LED wire to connect the drivers to the DSP, and I included LED strip lighting inside the machine that runs on its own driver and is independent of machine power. Also, during the troubleshooting process, I added an additional ground line to the chassis of the DSP controller, and a separate isolated ground line from the chassis of the LPSU directly to copper piping with an additional layer of plywood separating the LPSU from the chassis of the machine. The LPSU is still grounded along with the rest of ground lines through its power-in adapter, so its not off the floating potential.

[Tech_Marco]

When you see a flash or resetting is happening, that mean you have poor grounding for sure.
As I said, post your manufacturer parameters screen shot for review
The tics could be caused by bad motor or speed was too high. Check the mechanical parts as it may be lose somewhere

Marco

[zeitgeist]

Sorry, I missed the part about the manufacturers parameters. Its attached below now.

What recommendations do you have to improve grounding? Everything that ought to be grounded is indeed connected to the ground, and I also checked the grounding in the house to make sure its connected. I even added those extra ground-lines to be redundant, at least I thought. If the grounding wire is not thick enough gauge, could that be part of the problem? Am I also correct in noticing that the DSP controller itself isn't directly grounded? It appears its only grounded through the connection to the LPSU.

The motor tics also happen occasionally when test-firing the laser. At first I didn't realize the motors were moving until I did some further experimenting.

[Tech_Marco]

First thing: why you set the range to X:1200 and Y:900 ??
The workable of K40 is merely 340 x 220. So....

I saw that you set the motor driver to "16" which is fine. But for 16, I don't think that the 'um' is 4.87 or 4.9. It should be around 6.6 or 6.7 or around. (It has nothing to do with the resetting. I just curious)

Double check the AC plug installed on the K40. Pay a little attention that whether the "N" is connected to the case or not. In my previous experience, 99% (1% for system I didn't touch) machine made by "ShenHui" are having the "N" un-connected. Terrible tech issue there!

Trick (may work). You pay want to put a metal wire to the water container to ground it
I remembered that on ShunHui D350, statics was built-in in the water bucket.

Make sure the HV (red cable) is short and state away from any signal wires. The electromagnetic field caused by the HV cable is strong enough to make your hands hair straight up (someone has mustache should try it too)


Marco

[zeitgeist]

Hi Marco,

Thank you for the response after hours!

The area setting is 1200 x 900 because I never changed it after install. I wanted to get an exact measurement of the work area and I hadn't done that yet.

I'll re-run the um setting to see if it was done correctly.

Going by memory, I don't think the Neutral AC-in is connected to the ground on the machine. Based off your wording, I'm assuming that if its not, then it should be. I was wondering about the water as well. I've come across one other person who had static building up in their water, but I have yet to actually test for that.

A big part of my problem may be the HV line. I actually left the length of the wire coming from the LPSU uncut, so I will shorten that down as well.

Tomorrow I'll examine the AC in and post up some photos so I can make sure its wired up correctly. Last thing I want to do is directly charge the machine.

[Tech_Marco]

If you can, post the original picture from your previous engraving.
It looks not very good to me. It seems that it was over saturated.
You may import an .bmp or .jpg, then use the `Dither` function to make engraving better look

I just landed at Spokane, WA for my daughter`s volleyball tournament. Will stay here for 3 days. Anyone closed around here and like to meet with me, feel free to contact me


Marco

[zeitgeist]

I'll have to upload the photo later, its on a different computer.

I grounded the water bucket and shortened the HV cord going to the laser, and that has fixed the LCD resetting and motor tics, but I'm still getting weak power out of the laser.

I tried running a cut at 800 PPI, 100% power, and 5 mm/s which barely went a couple millimeters into birch plywood. The ammeter on the laser only read about 6.5 mA. Could my LPSU need adjusting to increase the current?

[Tech_Marco]

On the LCD, set the power to 100% and test fire. Check the current see how high it output. For 40W LPSU, you should see 20~22ma. If you can get 16~18, it is still good


Marco

[zeitgeist]

98% is the highest I'm able to set it. I set that earlier in the software, and the machine has not recognized that I increased it back to 100% (this is in the manufacturers parameters screen). So even when I manually dial in 99.9% on the LCD, it goes to 98%. But when test firing at 98% I'm getting just 14 mA.

If I try to cut a circle using the same settings in the LCD, I only get 6 mA at the same power.

[Tech_Marco]

LCD power setting is for the "Test" only. If you want LCD to bypass the software setting, you can change the mode.

Anyway, 14mA max is not good but not too bad. The max allow for the 32W tube is 16mA. You may disable the PPI and set 100% on the laser for cutting and you should get closed 14mA reading.

What kind of LPSU did you use? The stock one or bought a new one from us? The tube is the stock tube also?
Seems the tube may be not in a good shape if you can't get over 16mA from the LPSU. Air leaking, may be.


Marco

[zeitgeist]

The LPSU is one I just purchased from here, the tube is the one that came with the machine. Before doing the upgrade, it was cutting quite well, but I may have damaged it during the upgrade by putting stress on the positive terminal. I have a new tube en route that should get here Monday.

If I disable PPI, I do get about 13 mA when I send a command to cut at 100%. But if PPI is enabled, it won't go above 6.5 mA regardless of where I set it or the power. Shouldn't I be able to cut through things with the PPI turned on? It barely makes a groove as-is, even at 100% power, 1000 PPI, and 10 mm/s speed.

In case its relevant, for the version of LaserCAD I have (v7.43), I had to manually go into the program files to enable the PPI option. It was greyed-out before.

[Tech_Marco]

It is normal to see less current with PPI enabled. Remember that the PPI is outputting in pulse, not continuously

Marco