Help with Home Adjust Location

Mayhem

I recently installed a MicroSwiss direct drive onto my CR-10 and I'm having an issue with the print head wanting to move beyond the home position and start off of the bed.

I followed the instruction supplied by MicroSwiss and checked this as directed in the Configuration.h tab of the TH3DUF_R2 firmware that I am running, and set the home adjust as shown below:

However, this isn't resolving the issue. When I commence a print, the printer home and maps the bed. For the first three probing spots (3x3 grid) the sensor looked to be in the right position over the bed. However, when finished the third spot it 'bounced' back inboard and then was offset to the right (i.e. closer to the x-axis limit switch) for the rest of the mapping process.

Once it has finished mapping, it homes correctly (i.e. gently bounces off the limit switches) but then it tries to move past the limit switch and grinds the stepper motor. The two lines of filament purge are right over the edge of the bed.

Here is my Cura start code:

M117 Print Starting...

M75 ; Start Print Timer and Engage Fil Sensor if USB Printing

M84 E ; Disable E Motor for probe accuracy on direct drive systems

M117 Antiblob retract...

G92 E0 ; Reset Extruder distance to 0

G1 E-2 ; Retracts filament to prevent blobs during probing

G92 E0 ; Reset Extruder distance to 0

M117 Homing All...

G28 ; home all axes

M117 Homing Z Probe...

G28 Z ; home z again

M117 Probing ;)

G29; auto bed leveling

M117 Warming up

G4 S10; wait for heaters to recover

M420 Z0; Z fade

M900 K0; LA

M117 Purging extruder...

G92 E0 ; reset extruder

G1 Z1.0 F3000 ; move z up little to prevent scratching of surface

G1 X0.1 Y20 Z0.3 F5000.0 ; move to start-line position

G1 X0.1 Y100.0 Z0.3 F500.0 E15 ; draw 1st line

G1 X0.4 Y100.0 Z0.3 F5000.0 ; move to side a little

G1 X0.4 Y20 Z0.3 F500.0 E30 ; draw 2nd line

G92 E0 ; reset extruder

G1 Z1.0 F3000 ; move z up little to prevent scratching of surface

M117 Printing…

Any thoughts?

IMc

Did you set home home offset adjustment instead of probe offset

Mayhem

Thanks - I only set the home offset adjustment, as that is all that the MicroSwis instructions said to do: https://cdn.shopify.com/s/files/1/1210/0176/files/Leveling_probe_installed_with_TH3D_Unified_Firmware.pdf?v=1594851705

I don't like playing around in the firmware code, as it is all a black art to me.

I don't understand enough about how the settings interact with each other. So I just need to measure the distance of the nozzle from the centre of the probe in x and y or do I also need z (or do I just leave z at 0 given that the EZABL is set up and working)?

I ran the printer again and took some video, which I need to get off of my phone and edit. It actually overshoots before it probes the 3rd spot on the bed (front, far right) if that makes any difference.

IMc

Myself I leave z at 0 with my bltouch, if you probe is on the left side of you nozzle you have to put a - before you measurements in x and if its in front of the nozzle - in y

The image I posted was so you know what you are looking for in firmware

HouseOfBugs

I'd set the home adjust to 0 and see how it behaves (or disable it).

Mayhem

Thanks.

With the home offset adjust disabled, the probing positions are shifted left (i.e. the sensor is right on the edge of the bed. With them set to -5 and -10 the positions are similar to stock but it overshoots just before it probes position 3 (3x3 grid) and is then offset back to the left as a result. Grinds the stepper when the print starts and purges on the edge of the bed.

I had to chop the files up in order to upload them:

1. Start sequence

video-one.mp4

8MB

2. Mapping the bed. Note the orvershoot and bounce back on the third position

video-two.mp4

7MB

3. Trying to overshoot the limit switch and purging off the edge of the bed

video-three.mp4

5MB

Here you can see the purge lines on the very edge of the bed:

I hope these are helpful.

Mayhem

Well my weekend turned to crap and I got no time to experiment. However, I am wondering if the videos I posted assist in narrowing down the issue? I spoke to someone else who suggested decreasing the probing grid. Any thoughts or comments greatly appreciated.

IMc

Looking at your picture I would of thought x would be more than -5

Mayhem

Thanks. Moving x -5 puts the tip on the nozzle over the bed and it looks good when it maps positions 1 and 2. However, it overruns and bounces back inboard prior to mapping position 3, and then all subsequent positions are offset back towards the limit switch. Not sure if you had a chance to view the videos but the position shift is pretty clear. I'm trying to figure out why is is overshooting in video 2. I believe this is the main issue.

If I move it more (say -10) it is still going to overshoot and then be too far to the left again. Every time it grinds the stepper, as it is trying to move the hot end past the limit switch. When I get some time in the workshop I'll try and if it overshoots I kill the print. I really don't want to trash the stepper.

IMc

I see what you mean the x carrage skips back, it's as if the belt is elastic, have you charged the motors around to see if its the motor

Mayhem

Thanks - I haven't switched motors but I don't think that is the issue, as once it starts printing it prints fine. Of course, I am not ruling out the coincidence of the motor developing an issue at the exact same time that I changed the hot end.

Is there a way to test the motor without swapping it out?

HouseOfBugs

Check the coil resistance. https://www.th3dstudio.com/hc/guides/troubleshooting/testing-and-checking-your-stepper-motors/

Mayhem

Thanks Tim - I'll give that a try and report back.

Mayhem

Stepper motors are fine and working correctly.

I have fixed the problem.

IMc

Mayhem

What was it in the end

Mayhem

Embarrassingly I had zip-tied the cable loom a little too short. It was the loom that was jerking the carriage back toward the centre 🤦