Repeated rehoming of drum?
I'm running ZB firmware, but have in the past and did not see this. Recently - and more and more - I get the drum rehoming after unloading filament and before the selector moves to its new position.
It used to happen once or twice a print, now it happens once or twice per layer.
https://photos.app.goo.gl/N6MVfBBD5BQCVknW6
It looks at the end like I touched the drum, but it resolved without me risking my finger. 🙂 Sometimes the error seems to clear if I lift against the tension springs.
The only recent change was putting on the newer matched bondtech gears - could their extra tenths of a millimeter diameter cause this? My tension screws are roughly flush, where they've always been. Screws on the drum are snug.
Could the drum be flexing? My theory is the homing routine isn't getting repeatable home and keeps running?
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Re: Repeated rehoming of drum?
I'm wondering if the drum rubbing on the idlers could be getting a soft stop, which means the 3 don't average well, so it tries again.
I suspect turning up motor current would help. How might I go about adjusting the homing current?
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Re: Repeated rehoming of drum?
On TZB FW it re-homes in case of stall guard (crash detection) triggering on an axis. So this may mean one of these things:
1) The drum is bumping into something like a piece of stuck filament, causing it to lose steps
2) Too much friction on the drum. In my case, this was caused by the drum not being centered between the motor and the axle bearing, so it was rubbing against the axle bearing. Another possible cause would be having the tension springs screwed down too tight.
3) Stall guard sensitivity is set too high, this can be changed in the FW.
Adjusting the stall guard sensitivity should be a last resort, because if the problem is 1 or 2, that's a physical problem you should try to fix first.
Re: Repeated rehoming of drum?
It's not THAT it's homing, it's that homing isn't working. The fact that it homes twice or sometimes 30+ times is the issue.
Motor current or stall guard adjusts make sense.
The surfaces are clean. I think it's better with my stiffer drum.
Now I'm running the latest firmware and the homing maneuver is both faster and sounds "stronger". Now it works the first time.
I maintain an informal list of San Diego, CA 3D printing enthusiasts. PM me for details. If you include a contact email and I can add you to the informal mailing list.