motor y seem to get stuck and not moving smoothly

This is the video

still trying to upload video...

a

Sorry, I can not upload a video here, so I published it on youtube: https://youtu.be/oXsMHaDAzyM

are the rollers are too tight?

I checked the mechanics and that's okay. I disconnected the tooth belt and then I tested the engine. The problem is here: it works smoothly at very low speeds. when I increase the speed it rotates with interruptions and makes strange sounds.

Attached video:
https://www.youtube.com/watch?v=_5NTJg8dcX8

Hi there.

I don't know what your problem is but I also had a Y axis motor problem that manifested itself as intermittent resistance to drive.

I wondered if I had damaged my motor by generating back EMF by driving it too fast by operating the belt manually during 'mechanical tuning'.

I recommend getting a new motor, under warranty if you can. I paid for mine; it was only £25.

I disassembled my old motor (no obvious fault), removed the stator and reassembled it with the rotor free to spin on its bearings within the end caps. I used this in place of a normal motor to check drive resistance with the belt in place.

Doug

Thank you Doug, I will write to my dealer.

Stepper motors exhibit some strange behavior if one tries to drive them fast with no load. They exhibit a resonance which is normally damped by a driven load - this often occurs well below the normal maximum speed.

Your video appears to show the motor dithering back and forth even though driven in one direction - this often happens with unloaded motors near to their resonance frequency.

Could I suggest that before scrapping the motor, you firstly take up jvalencia's point and slacken off all 4 Y-axis rollers. Refit and adjust the drive belt, making sure that both gantry arms are exactly the same distance from the end plate. You might have to release the X-axis screw to achieve this (make sure the X-axis is still OK after this!!)

With power off the machine, move the gantry over the full Y range to make sure it doesn't tighten up at any point - if it does, it points to the bearings being mis-aligned with the leadscrews. If it tightens at the driven end, then slacken off the Y-axis screws (item 42) so that the extrusions self align. Re-tighten these screws and check that freedom of movement is unchanged.

Next, move the gantry to the other end of it's travel - there should be little or no difference in the freedom of movement. If there is, then the free end bearings are misaligned and you might have to remove some of the powder coating or even some metal as well to achieve best results. All this assumes that the leadscew is straight and the nut has been adjusted correctly as in operation 4.5.

Now is the time to check that the motor will drive easily at full speed over the whole Y-axis. If that's OK, then it's time to carefully adjust the rollers (I tightened mine until they could just not be rotated by hand). Whatever you do don't over-tighten these rollers, it's very easy to jam the axis by overdoing it!!

Good luck - it's taken a lot of words to explain something pretty straightforward!!

Peter

Peterg1000: I have been experiencing similar problems on my new ST2-600 build, so now, with your thorough explanation, I should be able to get everything "rolling" smoothly. Thanks so much for your help.

I followed the steps and found several irregularities in the drive pulley. still hear strange noises and have to intervene. engine runs better now, it seems that it was a software issue.

Thank you all!

Stepper motors exhibit some strange behavior if one tries to drive them fast with no load. They exhibit a resonance which is normally damped by a driven load - this often occurs well below the normal maximum speed.

This sounds exactly like what I was experiencing Peter.

I drove the second motor much more slowly so this didn't happen. For £25, I wasn't prepared to take any chances and was happy to scrap it.

All is well now in any case and I'll be chalking it up to experience.

Doug

Patrascanu - we all have these problems. Its bcz this machine is poorly designed.

Stepcraft will tell you to disassemble and reassemble the machine hoping something will get better.

I have the same problem on my x-axis.

I guess you will end up loosing some screws and working like that until machine will fail.

Welcome to the wonderful world of Stepcrap lack of quality & service.

I'm as well in this position.
I dismantled my machine many times.. and I still can't tighten my front and back plat as the machine will stall.

As well my.. circle milling looks not too well.. and am still having hard times figuring out where the mechanical issue is.
Needles to say the mail and experience of the persons (sometimes responding by mail), is either very low or they are not interested...

Id like to understand better how we should move by hand .. the Y axis while the stepcraft is OFF and how we should understand.. the play, or hard to move by hand at the end of the axis when he screws are tighten. I seem to be able to run only with them un-tighten and my Y axis is off by something like 0.44mm and my X axis is making errors of approx 0.23mm.

I seem to have even worst results if I make to circle patterns and drill them on cw and the other ccw.. as the backlash as well arrears and not sure how to correct it while using WinPC-NC. I must imput some steps in the WinPC-NC backlash settings, but I'm not sure how many steps correspond to my 0.23 and 0.44mm distances ?!! any idea ?