Belts not entensioning when applying tension

1

I was setting up my 4.1 with firmware 1.05 and ran calibration. It worked great. It was able to move around and the belts were tight. But when retract to install a bit after extending the apply tension does not pull in the slack all the way. It also sometimes release slack on the top left arm. I have tried applying tension before to the top belts but no luck. The bottom right or top right arms usually have some slack. I also noticed that sometimes the bottom right does not retract until the retraction force is above 1500. I have also taken it apart and loosened the screws a bit to see if it is too tight.

Is the retraction force being used when taking up slack? Because it seems to only be used when retracting.

Retraction Force: 1100
Calibration Force: 1100

Fitness: 0.6095035623959463
Maslow_tlX: 8.3
Maslow_tlY: 2388.9
Maslow_trX: 3692.2
Maslow_trY: 2379.7
Maslow_blX: 0.0
Maslow_blY: 0.0
Maslow_brX: 3693.1
Maslow_brY: 0.0

Edit: PS I have a deadline next week and I really need to get this thing working!

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2

The retraction force is used when you press the “Retract All” button, the “Calibration Force” is used when you press “Apply Tension” or “Calibrate”

3

It seems like the retraction force is increasing the more I am using it. I took the arm a part and I couldn’t move the belt gear at all.

Maybe it was screwed too tight?

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4

You could try adding a bit of silicone lubricant in there to help it move smoothly

5

I did add some lube and it works wonderfully now!

I replaced just about everything else (motor, belt, screws, berrings) but the lube did the trick!

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6

Excellent, I am glad to hear it!

7

Now I have a different problem. The belts are loosening after applying tension when I ask it to move, xy or z.

Things were working fine last night until one of the z motors died. So I replaced it and now this is happening. Maybe things have changed enough to need to recalibrate?

8

calibration is just figuring out where the anchors are.

if you hit the test button, does it report that it sees all the motors and
encoders correctly?

David Lang

9

I recalibrated and it works. I think it might be because I lowed the retraction force now that it was able to move better. I guess you cant change that after calibration or because it was so high 1800?

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10

Test seems fine

Test
Index.html Version: 1.05
[MSG:INFO: Firmware Version: 1.05]
[MSG:INFO: I2C Timeout: ]
[MSG:INFO: 10]
[MSG:INFO: All tests passed on Top Left]
[MSG:INFO: All tests passed on Top Right]
[MSG:INFO: All tests passed on Bottom Left]
[MSG:INFO: All tests passed on Bottom Right]

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11

I upped the retraction force and it is doing better but the belts do lack sometimes

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12

@bar @dlang The belts are still letting out too much slack as the machine runs.

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13

How much too much are we talking about? Is it like several feet too much or an inch too much?

14

So just after applying tension the machine lets out slack when I click jog in any direction. The upper left belt is so lose there is almost no tension on it.

As the machine runs the error seems to add up. Where its letting out too much slack on the opposite end its pulling. Eventually there is so much slack that its not stable and moves too much. Then I get the calibration error greater than 15 mm.

Let me grab a picture in a bit.

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15

Here are some pictures and a video
Google Photos

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16

This sounds to me like it could be a magnet issue.

When you press retract all what are the number that get printed out?

What do you see when you press Settings → Test?

17

Test output:
Test
Index.html Version: 1.05
[MSG:INFO: Firmware Version: 1.05]
[MSG:INFO: I2C Timeout: ]
[MSG:INFO: 10]
[MSG:INFO: All tests passed on Top Left]
[MSG:INFO: All tests passed on Top Right]
[MSG:INFO: All tests passed on Bottom Left]
[MSG:INFO: All tests passed on Bottom Right]

When I do retract all the numbers make sense to me. I have done retract and extend before and the numbers are about +/- 0.01

Do you mean retract all after I have applied tension?

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18

This looks pretty good.

The most likely cause for this would be that one of the magnets is slipping. That leads to the machine gradually losing its position over time.

When you run Retract All the numbers that it prints out are the difference between how much belt the machine thought that it had extended, and how much was actually extended. If that number is larger say 1-5 that would be an indication that a magnet could be slipping.

Pressing Retract All twice in a row will always lead to very low values, but if you extend the belts fully and then retract them again that’s a better test of if the magnet is slipping.

If it’s getting worse as time goes on that is all that I can think of as the cause.

If it’s not getting worse over time, then it could be just a funky calibration so running calibration again (potentially with a higher calibration force) might fix it

19

I was retracting, extending then retracting. The measurements were pretty close to +/- 0.04.

I just recalibrated and swapped the bit in directly. Its been really tight now.

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20

Been running it pretty much all night. I think it might have been a combination of a bad belt or encoder plus a bad calibration.

I swapped the encoder boards and added glue to the magnets. I also switched out one of the belts that was not totally straight all the time.

I would love to work through some of these common assembly / part issues with you to make a better self test / diagnostic. I feel like there should be an automated way to detect some of these issues.

I should have more time a couple weeks and I would love to dig into the code. The maslow 4 is so close to be something great!

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