Delta printer motor stall calibration
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see
https://duet3d.dozuki.com/Wiki/Stall_detection_and_sensorless_homing
The stepper drivers only update the stall detection state every 1 or 4 full steps, depending on configuration. So the actual position of the stall is uncertain to either +/- half a full step or +/- 2 full steps. This means that when using stall detection to replace endstop switches, the position defined by the stall is much less accurate than with typical endstop switches.
this is not accurate enough for deltas.
here is what i use.
https://de.aliexpress.com/item/32968709878.html
which i put on once for calibration, and if your endstops are good enough it will last several prints before you need to recalibrate again. -
I know that it's not accurate enough, but I wanted to give it a try anyway.
But as mentioned above the stall detection doesn't work at all
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M558 configures the probe
https://duet3d.dozuki.com/Wiki/Gcode#Section_M558_Set_Z_probe_type
P10 is for stall detection
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That's what I'm using in my macro above, but it doesn't seem to work
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The stall needs a short sharp shock to detect the back emf reliably. The squishy cardboard box may have too much give to it.
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Ah, ok. I thought it's actually able to detect the restisting force. But besides of that it's also not working when I just use my print bed. The nozzle hits the bed, the motors stutter a couple of times, but no probe measurement. Just horrible noises eek
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Well you're also trying to stall 3 motors at the same time. There's a lot of reasons it's not used with deltas. Stalling the carriages at the top of travel against the frame is one thing, but trying to probe the bed with stall is unlikely to work right.
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I know, I know, that's why I mentioned I like impossible things in my initial post. It's still kinda weird that I don't get any motor stall response at all.
I just wanted to give it a try, because it doesn't seem like people actually tried it. Everything I found so far were some calulations which said it's not possible. Therefore I just wanted to give it a try and post some more indepth details on that.
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It could work....
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Well, not as long the motor stall detection doesn't trigger at all. But for now I'll just play with an accelerometer, how hard can it be? xD
