Repetitive problems both in cutting and engraving

[fnaranjob]

Hi everyone,

I'm running into some problems both in cutting and in engraving with the 2012 DSP, when doing vector cutting/marking I see the beginning and end of the curves don't match, the problem is very repeatable, it happens in the same exact place of the cut everytime it doesnt matter if I put the workpiece in a different place in the cutting table, if I mirror the image and try again the problem is mirrored too so I'm guessing its not mechanincal but who knows, it even appears the same when I increase or decrease the image size.

Now about the engraving problem, whenever I want to make a small engraving I notice some sections of the image look shifted from the correct position, this problem is also repeatable, it happens in the same place of the engraving everytime, I noticed the problem appears whenever the engraving changes in width, if I put a rectangle around the engraved image the problem seems to dissappear because the X travel remains constant, I'm attaching some pictures of the problem, I hope somebody has run into something similar or has an idea of how to solve it.

[artofmystate]

I have the same issue. No matter where the material is cut in the machine, the same file always loosing position at the same area. I have tried everything I know to solve this issue. I changed speeds, accelerations, pulse edge, microsteps, stepper amperage, etc. Then I hooked up MACH3 to test the mechanical systems. After abusive speeds and accelerations using MACH3, my laser shows only a .0005" position error. So the mechanical system checkouts fine.

Could there be a grounding issue with the DSP?

Is the power supply for the DSP too noisy with EMI?

I tested the new software and firmware resulting with the same issue.

[twosoc]

Hey, this probably won't help, as you might have already thought of it, but I was having a similar problem until I started taping the corners down, the vibrations shifted the workpiece over slightly in the same place every time, must have been a particular movement that caused it to shift.

[Tech_Marco]

Hi everyone,

I'm running into some problems both in cutting and in engraving with the 2012 DSP, when doing vector cutting/marking I see the beginning and end of the curves don't match, the problem is very repeatable, it happens in the same exact place of the cut everytime it doesnt matter if I put the workpiece in a different place in the cutting table, if I mirror the image and try again the problem is mirrored too so I'm guessing its not mechanincal but who knows, it even appears the same when I increase or decrease the image size.

Now about the engraving problem, whenever I want to make a small engraving I notice some sections of the image look shifted from the correct position, this problem is also repeatable, it happens in the same place of the engraving everytime, I noticed the problem appears whenever the engraving changes in width, if I put a rectangle around the engraved image the problem seems to dissappear because the X travel remains constant, I'm attaching some pictures of the problem, I hope somebody has run into something similar or has an idea of how to solve it.

Please send me the .pwj5 file and I'll send it to the engineer for testing.
Also, please enable the "Gap Optimize" see if it help. Plus, change the "Pulse Edge" to other way see if it help also. See attached images. Let me know.


Marco

[fnaranjob]

Thank you Marco,

I'll try your suggestions today, I'm attaching the pwj5 files, notice I have the same issue in most files, it is not just this one

[Tech_Marco]

We tried but couldn't duplicate the problem on our machines. I'll launch another OS see if it help to fix your problem. It look like that it could be some 'compatible' issue as it may happen to a few users but not all.

Marco

[fnaranjob]

We tried but couldn't duplicate the problem on our machines. I'll launch another OS see if it help to fix your problem. It look like that it could be some 'compatible' issue as it may happen to a few users but not all.

Marco

By the way, I'm using leashine brushless servomotors and their drives, I understand servodrives usually have different pulse durations for the pulse/direction signals than stepper drives, but this problem seems to be happening to "artofmystate" too (sorry I don't know your name ), and he's using steppers, I also checked for backalsh everywhere and it is lower than 0.01mm, I'm using belt drives and belt speed reducers, what do you mean by 'compatible' issues?, is the DSP controller not compatible with some sevo/stepper drivers? It could be useful to make a list of all the incompatible drivers models we know of so far, from the leadshine's driver's manual I got that the duration of the pulse signal should be at least 0.85us, and the dir signal should be ahead of the pulse signal at least by 5us for reliable operation, I dont have an oscilloscope at hand, could you please ask the engineer if the DSP pulse/dir signals are compatible with this requirement?

I know I'm asking a lot but it would be nice to have a singal sequence chart of the PULSE, and DIR signals of the DSP, that way we could make sure the servo/stepper driver is compatible with the DSP before we buy it, the chart I'm mentioning looks like this one from my leadshine driver:

[baccus61]

I also had this same type of problem for years and could never find the culprit. I had an offset as well on most jobs if I went over 10"per sec.
I changed out everything except the power supply and in the end I bought a 48V switch mode power supply from China for $25 and that fixed the problem.
I don't know how or why but now everything works fine.
If you have a spare power supply then you could try it. I don't know if it would solve your problem but it fixed mine. It's truly a weird one.
Rich.

[Things]

Sounds like your power supply might have had a bit of ripple on it's output confusing the stepper drivers. Real easy to check if you have an oscilloscope - even the cheap $80 pocket ones can be helpful for stuff like that.


Dan

[liaoh75]

I have the same problem. I'm using Yaskawa Sigma 5 series AC servos. My servos run straight from 3phase 220VAC so no power supply issues in the loop. Had Yaskawa engineers come to verify. Still trying to track down the source of the problem. Doesn't seem like our Stepper counterparts are having this problem. Hope there is a resolution to this at some point in time.

[baccus61]

Hi liaoh75,
Did changing your pulse width from 1 to 10 fix this problem?
Rich.

[liaoh75]

Hi Rich,

Do you mean "pulse unit" from 1 pulse = 1um to 1 pulse = 10um? If that is the question, the answer is no, it didn't fix the problem. If that is not what you mean, then please clarify and I'd be happy to try anything.

Thanks,

David

[baccus61]

Yes. That was what I was wondering.
I have a few Yaskawa drives and motors that I need to get up and running but I haven't had the time to get my teeth into programming them. I wanted to know if that changed anything as I may need to do the same when it comes to finally setting up my motors.
It certainly is a learning curve. I sometimes wonder what it would be like for the people who develop these things? So much trial and error to get things right.
I don't really have any info for you though but I wish I did. Here's hoping you get it sorted out.
Rich.

[fnaranjob]

Some update:

I've found that the "Gap Optimize" option in lasercad does eliminate the problem for me to a certain degree, there are still some graphics that don't cut correctly sometimes, but if I cut a file without the option checked I get a LOT more issues, does anyone know exactly what the gap optimize thing does? knowing that would help finding the source of the problem, I have 2 more machines to build right now and I'm going to use a different brand of servos, let's hope the problem doesn't show with them as Marco suggested it could be a compatibility issue.

Fernando

[Telrad]

Just to chime in on this topic, I come from the CNC routing world and whenever people see problems like this it tends to a problem with grounding and shielding. Make sure that your servo encoder wires are shielded and grounded at the drive end. Also make sure that the motor wires are shielded and grounde as well at the drive end. Finally check the laser to make sure it is also shielded and grounded at the controller side.

I've built several CNC routers and whenever I have a problem with electronics the first thing I check is for shielding. The emf can be killer on fast moving motors!