Z-axis motors out of sync
I've be successfully printing for about 4 weeks now. After setting up the kit all tests past with flying colours and off I went. I started to get adventurous with new filaments and discovered that the z-axis needs to be recalibrated with each new material..... Not sure why? But hey, that's fine. However after calibrating the Z again I developed a problem, the z-axis motors started going out of sync. Basically what happens is the left stepper motor cogs/steps/rotates maybe 1/20th of a rotation with an audible click every 3s like clockwork when performing the x-y-z calibration process which results in the left z-axis rising while the right does not.....by the time the x-y-z calibration is finished the z-axis (or x-axis carriage) is leaning by about 20 degrees! And it can never find the 4th calibration point because it's now so far from the bed.
I've checked all the motor resistances, each motor is identical on both stages or out by 0.1 ohm. All motors pass the LED blink test. All motors have continuity.
Carefully inspected all wires, no indication of damage anywhere.
The power source is delivering 12.1V constant during all calibration tests.
Prusa sent me a new Rambo and still the same problem so it's not the board.
Here's the messed up part, if I run a Z-axis only calibration it passes every time, and the left z-axis motor does not cog/step/advance out of sync with the right motor. It only happens when both the z-axis motor and the x or y motors are powered simultaneously.
I'm lost for what do next. Prusa is scratching thier heads too.
I guess the only thing next is to replace the left motor and see what happens?
Any ideas how I can trouble shoot the problem definitively???
Aaron
Re: Z-axis motors out of sync
Did you try swapping over the 2 Z motor connectors on the RAMBo to see if the problem moves or stays where it is?
That would determine if it's an intermittent motor/cable problem.
For me, it's most likely to be a cable (or connector) problem. Replacing the cable and connector may well fix the issue.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Z-axis motors out of sync
Hi Peter,
Its probably something simple like that. I know for a fact my part cooling fan connection is garbage because I randomly fail the self test and if I wiggle the connection presto! it passes.
Here the kicker. I can sometimes print by doing a Z-axis calibration + a few failed V2_Calibration run (fails because the stepper motor advances). For example I just printed Benchy. Looks almost perfect. Did a X-Y-Z calibration right after........same problem again. Test fails because on stepper motor is advancing on its own during the calibration. Redid the Z-axis calibration, now it won't print the beer opener......go figure. It seems to always happen when all three axis' are moving at the same time. its like the z- receives a current spike and the motor bugs out.
Furthermore, the bed and nozzle are still hot from printing benchy and both fans are still running. I try the self test and guess what? It fails because of the nozzle cooling fan! Which is already running!!!!!!
I'll try new connections this weekend. But in the meantime, I'll be using this ultimaker 2+ my filament supplier lent me to get these prototypes finished. Maybe if the guys at Prusa can't help I'll buy this ultimaker, and chuck this thing in the bin. over 40+ hours of trouble "shooting" thus far. For my wasted time alone I could have bought a Ultimaker 3! Should have......
Aaron
Re: Z-axis motors out of sync
I try the self test and guess what? It fails because of the nozzle cooling fan! Which is already running!!!!!!
Well that would be because you don't answer the question correctly.
You are asked whether the fan is running. If it is, then you should select "Yes".
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Z-axis motors out of sync
Hahahha. Thanks Pete. I needed good laugh
Aaron
Re: Z-axis motors out of sync
did you try moving the axis manually ?
settings - move axis -z axis
move it up and down several times while also moving the wire loom .
probably some intermittent connection.
Re: Z-axis motors out of sync
You could also dismantle the connector from the wires on the motor and inspect the crimping of the individual wires. I saw another problem in this forum where there was a bad crimp.
/Henrik
Re: Z-axis motors out of sync
Henrik,
Do you mean crack open the motor case and have a look at the connections inside the motor or check the connector on the rambo side?
Aaron
Re: Z-axis motors out of sync
connectoe side is a lot easier to access... 🙂
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Re: Z-axis motors out of sync
Yep, I meant the the cable side... maybe it is possible to use a magnifier and look from the outside before dismantlling.
/Henrik
Re: Z-axis motors out of sync
I read a post in the reprap forum and the problem was that a wire had worked loose at the crimp terminal when the stepper motor made clicking sounds and was jumping eratically. So I think it is better to disassemble the connector and pull the wires holding the crimp terminal to reveal loose crimps. You might also need a magnifier (x8) to be able to see small movements of the copper strands when pulling the wire. All it takes for a stepper motor to fail intermittently is a bad crimp - where the copper strands seems to be in contact with the crimp terminal, but there is no good connection - comparable to a cold soldering joint.
/Henrik
Re: Z-axis motors out of sync
Hi Henrik,
I spent yesterday dismantling every motor, inspecting every wire and every connection. Everything looks good and it managed to pass the x-y-z calibration this time around! But then the problem surfaced during a benchy test print. Must be a fault somewhere...... How to find it if not visually now....
Aaron
Re: Z-axis motors out of sync
I would use a mobile phone set to vibrating mode during receiving a call and mount it on one z-stepper at a time. Then you could move the z-axis up and down, wiggling the wire looms and at the same time calling the phone. This may perhaps reveal a bad wire or a connector if lucky.
Another route to reveal a bad wire would be to write/adjust a gcode file to move all axes simultaneously (if possible) and wiggle the wire looms.
A third option would be to use the extruder stepper motor as a vibrating source - unmount it and tape it to one z-stepper at a time and handcraft a gcode file to extrude and at the same time highten/lower the z-axis.
/Henrik
Re: Z-axis motors out of sync
Hi Henrik,
I soldered every connection this morning. Nothing changed. Must be a bad motor?
Aaron
Re: Z-axis motors out of sync
Yep, it sounds as the motor is faulty. As a last test - you could put the motor in the freezer for a couple of hours and test the coil resistances if they differ from the other motor. If you have a heat gun or a hair dryer you could test the coil resistances when hot as well. Maybe there is internal discontinuity in the coils intermittently.
/Henrik
Re: Z-axis motors out of sync
Hi All,
Just wanted to close this topic out. The problem was a faulty motor and that's it.
Thanks for all your feedback.
Aaron
Re: Z-axis motors out of sync
I am having this exact same problem. Thanks for your post. I suspect a faulty motor now. I’ve contacted support. Any update on your end?