Weird laser head movement problem

[Elias Rautio]

Hello everybody!

I am building DIY 1500x1000mm 80w laser machine, and I'm having a weird problem on laser head movement. If I move laser head manually from controller screen arrows or when it is homing it moves normally. When head is homed and coming back to previous position it starts to move weird. It looks like it would lose signal from controller to driver multiple times over and over and the laser head is kind of "jumping" forward constantly accelerating and decelerating. Same problem happens when cutting or framing. It seems like when telling machine to move constantly forward ( moving manually or homing) it works good, but when it is told to move specific amount it starts misbehaving.

I think you need to see a video, explanation is a bit confusing:
https://drive.google.com/drive/folders/ ... sp=sharing

I had previously smaller generic chinese laser wich I used as a organ donor. I harvested Ruida rdc6442s-b(ec) controller and psu, 80w laser tube and psu from it and everything worked fine before wiring them to my new machine. Other parts I bought new (bigger closed loop stepper motors, drivers and psu for drivers etc).

I have checked motor and driver wirings many times, rewired with new wires, tried unplugging everything else from controller except drivers, I have tried different drivers and different stepper motors, I have tride open loop mode. Nothing seems to help. I am all out of ideas, no idea what's wrong.
Could it be some configuration error or software error I can't figure out? Any ideas what could be wrong?

I appreciate any help, I have been stuck over month on this and it's making me crazy!

[Gene Uselman]

I finally got the first vid to play but did not see anything really unusual. You are using the Vendor files from the donor machine and that would be my first place to examine. We have generic 'Rescue' files, I would choose one as similar to your current machine as possible [I don't know how common the upper left home position is- none of the machines I have worked on have had that config- be careful] and save the files you now have first. Gene

[Elias Rautio]

I filmed 4k 60fps by mistake so file size is really big and preview takes a lot of time I see. I can take better video tomorrow.

Problem is better seen in the second video. In first video I show that movement is normal when moving manually from controller and problem is only seen short time after homing.

[Gene Uselman]

Just noticed you are in Finland... I grew up in a little German town in Minnesota, surrounded by little Finnish towns. Spent six years in the National Guard with a bunch of Finns, wild people... lots of fun.

[Elias Rautio]

I have heard there are lots of Finns in Minnesota. Finns are kinda their own breed

I tested vendor rescue files, it didn't help.

I added a new smaller file size video in the drive link. You can see it is homing correctly with one smooth movement but after that it starts misbehaving, accelerates and decelerates in middle of moves. Very weird problem and it is making my machine useless. I am really close of buying new controller but those are not cheap...

[Gene Uselman]

I have a couple I could loan you if you drop in tomorrow? I cannot read the speed screen on the controller readout- does that change when you are having the speed change problem? Just watched the third video- if you run that rectangle over and over, does it repeat the speed changes exactly?

[Elias Rautio]

Controller screen speed readout is staying same, but stepper drivers screen speed readouts changes when problem is occurring.

If I run that rectangle over and over it seems it is repeating speed changes exactly same spots

[Gene Uselman]

That would point toward the controller, or a program 'stuck' in the controller somehow? I assume that it worked normally in the first machine? Perhaps check all your wiring connection to the controller one more time?

[Elias Rautio]

Everything worked perfectly on the first machine. Maybe something is wrong in controller or program, resetting to factory did not work tho.

I have gear reduction on both axis and had 40k subdivision microstepping so it was like 0.05um per step. I thought that maybe this is too much and it is more than controller can handle (400kHz or so pulse signal) so I dropped it down to 400 subdivision microstepping. Now laser head moves doesnt stop in middle of moves and it seems to go right path, but it still accelerates very slow. Changing acceleration on vendor settings does not affect at all to acceleration speed... Really weird again

[Elias Rautio]

Hi Gene, I am looking for new controller, I am currently comparing different models. I see you have rdc6445, is it good or would you recommend some other controller? One thing wonders me; RDC6445 says in description it can control fiber laser source, can this be true? It would be fun some day to try upgrade second laser head with metal cutting fiber laser. Dedicated fiber laser controllers costs thousands of dollars tho so I wonder if it can be true for rdc6445