Having worked consistently well for 5 years my Lowrider V2 has started malfunctioning……
Whilst cutting recently my z axis started creeping. So it would go to cutting height but slowly increase as the cut went on. My cut was to levelling the bed so the z was not moving up and down constantly, it wasn’t as if it was skipping steps as tool went on and off. Rather both left and right z motors would creep up by 5-10mm over the course of the cut.
As both motors were moving, i tended to think the problem was electrical. After a lot of troubleshooting I decided to replace my arduino ramps board and all the drivers. I flashed the new board with the latest Marlin. I set all the Vref to 0.7V and can confirm i have 12v whilst the machine is moving. I’ve checked all the Dupoint connectors and all look ok. However, the machine is now behaving very erratically.
All axis are behaving erratically, sometime moving normally and then skipping steps or losing power. The z motors seem to be the worst, losing power, coming back on and then losing power again. The steppers are also making some very strange noises. When I run a test GCode, the x is only moving to about 90% of the required distance, so maybe going to X1100 instead of X1200. The problem exists when controlling it from the controller or through repetier host.
The first video here shows me moving the z axis on the controller. At first it moves, then powers off, then powers back on and continues to move. The motors do not sound healthy, I do not recall them making that noise previously.
The second video is me raising the z 30mm through repetier host. As you can see it moves then powers off, then powers on, then off, on and continues to do this after I finished recording……
What’s annoying is I’ve had a machine working perfectly for 5 years, and now it has decided to behave like this.
So the z was rising, not falling down over the duration of the mill. That was why i guessed electrical.
Thanks for highlighting the z motors are overheating. Could i need new steppers? I’ve always run these at 0.9V, but now they seem to be overheating at 0.7v… I plugged in a spare stepper and it seemed to be behaving as erratically as the two connected on the z axis…
I have managed to fix one problem, i reflashed the board with an older version of Marlin and the x axis is now moving to where it should be… small blessings.
One thing, when i take a multimeter reading for the vref, as soon as my screwdriver touches the variable bolt on the driver, I get quite a loud buzz… is this normal?
Jeff said (and I agree) your stepper DRIVERS are possibly overheating or are misconfigured.
I think you are using stepper to describe the driver and motor to describe the stepper motor.
Your stepper motors could also be overheating, but to tell takes measurement of the motor temps.
Normal practice is to use a non-conducting screwdriver to do the adjustment.
Is that what you have?
This symptom is very much not normal. Motion systems don’t rise up in defiance of gravity.
Is your Z axis is trending higher than expected over a job and your job has regular up and down motion in Z? If so, then it seems you are either losing steps when doing Z- moves or…
With those symptoms i guess the other way- slightly loose endmill being driven up through the job.
Have you marked / measured the protruding length of endmill to show it isn’t moving around?
(I don’t think this is the issue based on your video)
That implies you changed firmware recently. From what to what?
Did these symptoms start after the firmware change?
You could also have incorrect driver config in firmware.
What drivers are you using?
If you have firmware set up for a different model of stepper drivers, you will get very weird behaviors.
I think I’ve managed to fix the problem but still not entirely sure what was wrong…
I ended up replacing the board and drivers and rechecking all the wiring. It seems to have worked.
I checked all my grub screws, but they were fine. The z was definitely rising as i’d checked it with calipers before and after the print. The z axis driver I replaced did have some scorch marks on its underside. I’d been milling wax and i think some wax has got in behind it. Could this have been the cause?
I said driver, but it was the Arduino directly below the driver. Here is a pic, I’d already scraped off the burnt wax. It was machine wax, so wax mixed with plastic, so had a melting point of about 150degreeC.
It’s plausible that there was some conductivity in the wax, making for who knows what kind of pull-up/pull down path and it could absolutely have caused bizarre stepper driver behavior.
what is weird is since changing the board and drivers, the motors won’t tolerate a Vref above 0.7V. For years I’ve been running my old drivers much higher, all closer to 0.9 and maybe even higher for the z axis. Now they just lose torque, switch off then come back on… Could this all be caused by the new board and drivers?
