Stallguard not working
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the low settings for M92 X and Y should be quite typically for a belt driven carthesian printer. but maybe that is the problem. I just tried again and it still won't register. maybe also my current reduction to 30% is at fault. Or my jerk and acceleartion settings. I give up for now. maybe i can get it to stopp skipping layers by crancking up the current(which my last board did). Or I have to stop using mikrostepping, as that also seem to loose some torque for the single steps
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As I understood the H settings are to prevent too many wrong triggers. Of course I could try to reduce it but 200 (which is also the dfault) should be the correct settings for my motors. And Yes: I started a print ech time I tested if the stal detection was working
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but now that I think about it , that might be what stops me here, as the direct driven belts have the low steps per mm values, I might have been slightly below that vaue of 200 steps /s
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@xorlosch said in Stallguard not working:
I might have been slightly below that vaue of 200 steps /s
That's what I mean. Try setting it lower. 100 or even 50 just to see if you can even get a trigger.
@xorlosch said in Stallguard not working:
maybe also my current reduction to 30% is at fault
You're only using 30% current?
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Ok that worked. I went to an agressive S-50 H10 and it instantly triggered. So now I have a at least a starting point for finetuning. I will post my settings when i am done (in the next days).
30% I had as reduced power for my stepper motors :M906 X1050 Y1250 Z1100 E900 I30
would that be too low? -
@xorlosch said in Stallguard not working:
30% I had as reduced power for my stepper motors :M906 X1050 Y1250 Z1100 E900 I30
would that be too low?Do you mean the I30? That's for idle hold, not normal operation.
The current for X Y and Z look reasonable, but as I said earlier. Target 70-85% of the max for the motor.
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yes those values I had both set to 70%. now i increased to 82%
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I tried setting up the stall detection but the axis is just too slow for stallguard to work. seems to be better suited for delta printers or core xy than carthesian printers :(. I had to go lower than H50 to detect stalls and then acutally all o them were false and it did not trigger on any real stalls. I will try installing smaller toothed gears for te belts (so that the motor neeeds more stes per mm) but i don't have high hopes. Has anybody got the Stall detection to work with carthesian printer with ow steps per turn?
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@xorlosch said in Stallguard not working:
I had to go lower than H50 to detect stalls
What was the S value?
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@Phaedrux with an S value of 7 or lower i detect a lot of false stalls. with a higher vslue i detect no stalls. but eitherway with both higher and lower s values (as low as 3) i could not detect real stalls.
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@xorlosch Bearing in mind the limitations of stall detection https://duet3d.dozuki.com/Wiki/Stall_detection_and_sensorless_homing#Section_Limitations_of_stall_detection
- What motors do you have? Are they high inductance?
- What speeds are you trying to measure? What is your standard printing/travel speeds?
With you X and Y steps of 44.3 steps per mm (which is pretty low, nowadays), and 16x microstepping, this means you get 2.769 FULL steps per mm. If you're printing/moving at 50mm/s, that's 138 full steps per second, which is under the default H parameter of 200 full steps per second. You would need to move at 73mm/s to hit this. An H value of 50 is 18mm/s, which seems very slow, and is unlikely to produce good results. Are you really moving the axes this slow? Try reducing your accelerations (M201) to see if that helps.
You could increase the full steps per mm by changing pulleys, as you've suggested, changing motors to 0.9º step angle motors, or use a gearbox on the motors. It just depends how important Stallguard is to you, and how much you're willing to spend to get it working!
Ian
Bed-slinger - Mini5+ WiFi/1LC | RRP Fisher v1 - D2 WiFi | Polargraph - D2 WiFi | TronXY X5S - 6HC/Roto | CNC router - 6HC | Tractus3D T1250 - D2 Eth
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@droftarts : not quite sure what the inductance of the motors is, but it really seems like the low speed is the problem here. As I mentioned the frame and motors of my printer are still the original Ridgidbot, which had some... let's say interesting design choices ;). The X and Y axis were using huge 36 tooth gears (with 2mm width gives about full 2,78 steps/mm). I acutally had bought allready smaller belt gears with 16 tooth but with the old ridgidbot overheating was the bigger problem so i skipped installing those.
But now I will for sure install those! That should bring me then up to 6.25 steps/mm which would corespond to 32mm/s for a reasonable H value of 200. Am I correct? I hope that will work better then. (Which it should as then the motors have more torque at the same time also with the smaller bet gears)
Just for interest: how many full steps does your cartesian printer use per mm? -
@xorlosch said in Stallguard not working:
Just for interest: how many full steps does your cartesian printer use per mm?
The ender 3 for instance uses 80 steps per mm on X and Y. And that's 200 steps per rev motors, x16 microstepping, 20 tooth pulleys, and 2mm belt pitch. If you used 400 steps per rev motors or 16 tooth pulleys it's up to 200.
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@xorlosch my Cartesian machine uses T2.5 belt with 16 tooth pulleys, 16x microstepping, 1.8 degree motors, for 80 steps per mm, or 5 full steps per mm. I usually print at 50mm/s max, and a lot of moves are half that speed. 40mm/s would be the target speed with this setup and H=200, but I’d probably have to drop H to 100. But I also haven’t set up stallgaurd to try it out! Perhaps tomorrow...
Ian
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Thanks. Then it sound as if we are in the same ballpark at least. I also could find an old datasheet in the net for my motor: it has 2.5mH per phase.
I actually like to print as fast as i can ;). In the past with the original setup i pushed up to 100 mm/s. But right after switching over to the Duet wifi I never quite got it back to work again as good as before ( I think the motors were runing near their current limit before). Still some tuning to do. Small prints are fine now, but with even midsize prints I get now all those layer shifts and that is why i was trying to get the Stall guard activated. And more torque will help me too
