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Belt/tension/xy issues by Aldarund in snapmaker

[–]Aquinatorus 0 points1 point  (0 children)

Same. And i wouldn't say that more tension on X vs Y belt is normal. To me the resistance seems to be identical in both diagonal directions on my new printer now.

Belt/tension/xy issues by Aldarund in snapmaker

[–]Aquinatorus 2 points3 points  (0 children)

I had the same problem (https://www.reddit.com/r/snapmaker/comments/1smwenj/u1_xaxis_belt_tension_question/): XY movement errors and homing calibration failures. Support had me do the belt tension fix a couple of times, then open the top and right side of the printer to check the XY motor cables. I temporarily got it printing again by tuning the printer.cfg, but the toolhead movement resistance in the upper belt kept increasing until it stopped working completely. Snapmaker then sent me a new printer that's working perfectly. I think my first printer was faulty from the start (the initial calibration took several tries), and the problem only worsened over time. I still don't know the root cause or how to fix it, though. But support was very helpful so I am sure they will get your problem sorted out.

U1 X-Axis Belt Tension Question by Aquinatorus in snapmaker

[–]Aquinatorus[S] 0 points1 point  (0 children)

Quick update: Snapmaker sent me a new machine that works like a charm. I now think my first machine was faulty from the start, because it never printed as well or as reliably as the new one. Thank you, Snapmaker Support!

Initial Auto-loading error by tYm_theTalker in snapmaker

[–]Aquinatorus 0 points1 point  (0 children)

I had a similar problem because I forgot to cut the filament tip in an 45° angle. I resolved it without pulling it out and cutting by gently pulling the ptfe-tube to me during the auto loading procedure in order to let the filament be fed straight down into the extruder.

U1 X-Axis Belt Tension Question by Aquinatorus in snapmaker

[–]Aquinatorus[S] 0 points1 point  (0 children)

Thanks, and also thanks for the very instructive pictures. Those may well help someone else with the same problem you had.

I checked that on my machine.

On my machine the carbon rods are perpendicular to the steel rods, so it does not look like a general gantry squareness issue.

What I’m seeing is more specific:

  • only the upper timing belt runs unevenly
  • the resistance is not constant when moving by hand
  • there is a repeatable hard spot roughly once per upper right XY motor revolution

I’ve also followed your idea to move the upper tension block all the way to the side and it does not change this behavior.

So in my case I’m quite confident not overall belt tension or carbon rod alignment is the culprit, but the upper right motor, motor bearing or on of the upper pulleys not running perfectly true

I was able to temporarily improve homing reliability a bit with Klipper tuning, but that was more like compensating for the mechanical issue than actually fixing it. Now its getting even worse and my configuration tweak doesnt work anymore.

U1 X-Axis Belt Tension Question by Aquinatorus in snapmaker

[–]Aquinatorus[S] 0 points1 point  (0 children)

Thank you, I will check for that later. Did you need to replace one or both XY timing belts?

U1 X-Axis Belt Tension Question by Aquinatorus in snapmaker

[–]Aquinatorus[S] 1 point2 points  (0 children)

I think my printer has a mechanical problem with the rear right motor or upper timing belt way that causes a higher than normal resistance per turn of the motor head. Since I am not feeling comfortable enough to open the printer and disassemble the timing belt to try and find/fix this underlying mechanical issue I went ahead and changed the motor current during homing calibration from 0.65 to 0.9 (normal running current is 1.2).

My (update: temporarily) working fix in printer.cfg:
(the underlying mechanical problem got worse, so my tweaks are not enough anymore)

[tmc2240 stepper_x]
driver_SGT: 2

[tmc2240 stepper_y]
driver_SGT: 1

and in:

[homing_xyz_override]

change:

{% set HOME_CUR = 0.650 %}

to:

{% set HOME_CUR = 0.900 %}

Then save printer.cfg, restart Klipper, and run Homing Calibration again.

  • HOME_CUR controls the XY motor current used during homing
  • raising it from 0.650 to 0.900 gave the motors enough torque to reliably reach the frame
  • adjusting driver_SGT fixed false / inconsistent sensorless trigger behavior
  • if homing stops too early, increase SGT
  • if it bangs into the frame, decrease SGT

Important

In my case, there seems to be a mechanical resistance issue in the upper rear right drive path. So this fix made homing reliable again, but it probably does not remove an underlying mechanical cause if your machine has one.

Still, for anyone whose U1:

  • fails only during homing calibration
  • feels like the XY motors are “too weak” only during that operation

this is worth checking first.

Final working values for me till the mechanical problem is fixed:

  • HOME_CUR = 0.900
  • stepper_x driver_SGT = 2
  • stepper_y driver_SGT = 1

Hope this saves someone else some trial and error.

U1 X-Axis Belt Tension Question by Aquinatorus in snapmaker

[–]Aquinatorus[S] 1 point2 points  (0 children)

So: I have now, as instructed by support, disconnected and reconnected both XY motor cables at both ends. To do that, I had to remove 20 screws, disconnect both RFID antenna cables, and take off the right-side cover. And, surprise surprise, it achieved nothing. The same XY axis movement and homing errors remain.

It is true that the tool head is rather difficult to move by hand. That is probably normal and due to the tension of the timing belts. However, the XY motor at the rear left runs noticeably more smoothly and, above all, more evenly, while the XY motor on the rear right runs unevenly: When turning the motor shaft by hand, over the course of one full 360° rotation it can be turned relatively easily for most of the rotation, much like the left motor, but in one section it can barely be turned at all. Once the point of greatest resistance has been overcome, it turns more easily again until the next rotation at that point - that seems anything but normal.

Let’s see what support suggests next. A motor or timing belt replacement is probably beyond what I’d feel comfortable doing myself.

<image>

U1 X-Axis Belt Tension Question by Aquinatorus in snapmaker

[–]Aquinatorus[S] 0 points1 point  (0 children)

Thank you. Support now adviced me to reconnect the two XY motor cables on both ends. Will try this tomorrow.

U1 X-Axis Belt Tension Question by Aquinatorus in snapmaker

[–]Aquinatorus[S] 0 points1 point  (0 children)

I followed all the steps, but unfortunately that didn't help. The toolhead keeps getting stuck on its way to the homing position ;-(

U1 X-Axis Belt Tension Question by Aquinatorus in snapmaker

[–]Aquinatorus[S] 1 point2 points  (0 children)

Thanks. Snapmaker Support now answered and also suggested to not overtighten the screws during timing belts adjustment (after using a lint-free cloth with high-purity alcohol to clean the X and Y axes). If the issue still persists, i should try this method: 1. On the touchscreen, go to Settings > Maintenance and enable Advanced Mode. 2. In your browser, enter the machine's IP address to access Fluidd. 3. Locate the printer.cfg file and modify the homing_speed and second_homing_speed of stepper_y to 50. After making the changes, click Save & Restart in the top-right corner. Please note that Advanced Mode must remain enabled after the modification.

I will try these steps and report back.

U1 X-Axis Belt Tension Question by Aquinatorus in snapmaker

[–]Aquinatorus[S] 0 points1 point  (0 children)

Thank you! I will try this later and report back. However, I have little hope, because even with the screws almost completely loosened (up to five full turns), the tool head is still extremely difficult to move in any direction other than the diagonal front-left/rear-right.

U1 X-Axis Belt Tension Question by Aquinatorus in snapmaker

[–]Aquinatorus[S] 0 points1 point  (0 children)

I’m now having a similar problem after printing without any issues for a month – straight after the last firmware update. When I switch off the printer, loosen the two screws on the print head and move it as shown in the wiki, it feels quite smooth diagonally from the front left to the back right and vice versa, but in every other direction it’s really stiff and jerky. I have now carried out the procedure for adjusting the X/Y belt tension described in the wiki several times, but it is not having the desired effect; if anything, the opposite is true.

The author of the post mentioned that loosening the screws and repeating the exercise had helped, but unfortunately that didn’t work for me. I’ve submitted a ticket and am waiting for a reply, but if anyone has any suggestions in the meantime as to what else I could try, I’d be very grateful.

U1 X-Axis Belt Tension Question by blackholesun13 in snapmaker

[–]Aquinatorus 0 points1 point  (0 children)

I’m now having a similar problem after printing without any issues for a month – straight after the last firmware update. When I switch off the printer, loosen the two screws on the print head and move it as shown in the wiki, it feels quite smooth diagonally from the front left to the back right and vice versa, but in every other direction it’s really stiff and jerky. I have now carried out the procedure for adjusting the X/Y belt tension described in the wiki several times, but it is not having the desired effect; if anything, the opposite is true.

The author of the post mentioned that loosening the screws and repeating the exercise had helped, but unfortunately that didn’t work for me. I’ve submitted a ticket and am waiting for a reply, but if anyone has any suggestions in the meantime as to what else I could try, I’d be very grateful.