Maslow 4 - moves in unexpected direction when jogging & unspools belts

Aloha,

After finally getting a decent calibration, I used jog controls to move the sled to home. The first move or two was as directed (100mm diagonal down right), but after that any jog in any direction moved down right and significant slack developed, to the point where I had to stop and sort it out.

My calibration was with a 1400 current threshold for both retraction and calibration. Can I increase those thresholds without rerunning calibration?

Mahalo,

1 Like

David Negaard wrote:

After finally getting a decent calibration, I used jog controls to move the
sled to home. The first move or two was as directed (100mm diagonal down
right), but after that any jog in any direction moved down right and
significant slack developed, to the point where I had to stop and sort it out.

My calibration was with a 1400 current threshold for both retraction and
calibration. Can I increase those thresholds without rerunning calibration?

you can, but they only affect retraction and calibration, during normal
operation it will go up to 4000

David Lang

2 Likes

This sounds like a bug maybe unrelated to calibration? I’m not really sure what is happening there. I would start out by just doing power off and back on followed by Retract All → Extend All → Take Slack and see if that fixes it.

1 Like

Mahalo for that clarification. I will continue to strive.

1 Like

I did as you recommended (twice) and when I jog, some belts slacken to allow movement and do not take up that slack. That seems to be the relevant symptom. Top right and bottom left were the ones I noticed most because I was jogging down right, but trying multiple jogs I see the same symptoms on any belt.

1 Like

David Negaard wrote:

I did as you recommended (twice) and when I jog, some belts slacken to allow
movement and do not take up that slack. That seems to be the relevant symptom.
Top right and bottom left were the ones I noticed most because I was jogging
down right, but trying multiple jogs I see the same symptoms on any belt.

retraction force would not help this.

what was your calibration fitness?

are you sure the Z was all the way down when you did the calibration?

David Lang

2 Likes

I’ve seen the same behavior but didn’t spend the time to find a repeatable pattern or document it. Anecdotally it seemed to happen to me as I did repeated diagonal jogs toward the bottom left of the workspace. I wonder if the logic to unspool some of the trailing belts is being over aggressive in its calculations as the machine is further away from center?

2 Likes

Bob Craig wrote:

I’ve seen the same behavior but didn’t spend the time to find a repeatable
pattern or document it. Anecdotally it seemed to happen to me as I did
repeated diagonal jogs toward the bottom left of the workspace. I wonder if
the logic to unspool some of the trailing belts is being over aggressive in
its calculations as the machine is further away from center?

it sets all the belts to the length that it thinks it needs for that location,
if you are getting a lot of extra belt, that indicates that the frame size does
not match what it thinks it does (bad calibration), or that the retract/extend
cycle didn’t fully retract the belts (which would lead it to thinking the belts
are shorter than they actually are)

David Lang

2 Likes

Also double-check you have the arms in the right order, and have zeroed the Z axis (drive it down until it clicks with no bit in it, then hit zero-z button on the setup dialog).

2 Likes

I was not hitting zero-z in setup! Otherwise, all good. Arms are in the right order.

1 Like

I started over—flashed the latest firmware and installed fresh index.html.gz and maslow.yaml, and got a good calibration and everything seems to be working. No more slack belts, no more odd directions, none of that.

Part-way through a cut, it stopped due to an overcurrent condition, and said I could restart at line 91? I have no idea how to do that, nor do I know why it happened. Maybe feed is too fast?

I’ve been having similar issues with over spooling. I really gnawed a belt yesterday in the process.
Double checked the arm install order which was correct, and I have my z-height all the way down with no bit when calibrating.

It’s difficult to know what I should expect in “normal” operation. I was beginning to just assume the over spooling is part of operation. Then I had one go where the Maslow actually tensioned everything and it seemed to be moving correctly. That was followed by more errors.

I left it yesterday with

[MSG:WARN: Position error on Bottom Left axis exceeded 15mm while running. Error is 15.057mm Counter: 6]
[MSG:WARN: Previous error was 15.057mm]
[MSG:ERR: Emergency stop! Stopping all motors]
[MSG:WARN: The machine will not respond until turned off and back on again]

I’m assuming the frame measurements need to happen from the center of the bolts that hold the belt ends?

I’m also having an issue where when I update the firmware, the startup messages in the console show the previous version. Was saying 0.74 after I had update to 0.75, and after updating to 0.76 yesterday, it now says 0.75. Issue persists even follow restarts.

This is an issue that I’m working to track down right now, but it’s not anything that you are doing wrong. It seems like it might be related to EMF, and the question we’re working on right now is is there a source of EMF that we can reduce or can we make the code more robust to handle it without issue. 100% not your fault. Hopefully this week’s update will help

1 Like

Hey bar, thanks so much for chiming in and letting me know. Really appreciate it. I’ll be gone a lot over the next two months, but if there’s any more information I can gather for you to help in troubleshooting let me know. I’d either have to tomorrow, or July 1-3.

Also, I didn’t realize the Maslow had caught a belt when I was most recently working with it and it snapped it completely. I’m working on a smaller table right now, but I’d like to replace the belt if possible so I can have the full length to work with when I’m ready for it. Can you point me where to purchase them?

Thanks for all the work you do making cnc available! It’s one of the coolest projects out there.

1 Like

Absolutely, we’ve got all the spare parts up in the shop here: Shop — Maslow

Getting that bug fixed is the top priority right now because it seems like it’s the last thing holding a lot of folks back right now so we should have a solution ASAP!

1 Like