Just dropping some notes here, for my future self, and for those still using OG Maslow 4 gear.
15mm Error
Especially if you are seeing this on just one belt.
It can be caused by the cumulative impact of a retraction fault. Gradually the belt gets a little looser and a little looser, until it crosses the 15mm threshold.
Which brings us on to
Retraction Faults:
- Idler gear seizing up on its shaft. This definitely impacts retraction. The latest arm design includes bearings for the idler gear’s shaft.
- Belt spool jamming. For this, my guess is that a small amount of dust gets caught in the screw hole clearance slots on the arm assembly, and moving the M4 around can dislodge just enough to impact retraction. A fault that can come and go.
Solution for both, ie. if you’re fixing one, do both of them, is:
Cleaning
Pull the arm apart, blast everything with compressed air, meticulously clean everything.
Pay special to the crevices, for example, between the teeth on the gears. I’ve found that engine degreaser, WD40, or the like, helps with this.
Then use some ‘dry’ lubricant. I’m currently trying some PTFE spray.
Sometimes the ‘Belt Spool Jamming’ problem won’t really go away. I’m guessing a slightly wonky plastic casting?
If you’re having to keep upping your retraction force value just to get things to work, then that’s a sure sign that an arm needs some maintenance.
And if you’re fixing that, then also …
Can’t Extend Belt
It just won’t budge, and you’re running original kit.
The original encoder boards, mine are v1.06, were missing a ground connection for pin 1 on the hall effect chip. The solution was to get a gob of solder from pin 1 to the nearby capacitor.
However, if you weren’t having problems then you didn’t need to do this. Except …
It seems that improvements with the FW have exacerbated this issue to the point now that if you’re running v0.87 and onwards it’s now a requirement to fix that missing ground connection.
PS. not actually a software bug, but a hardware bug made apparent by software improvements.