Is Stall detection a reliable safety feature w/ MB6HC
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Thanks for the input and good point on the torque multiplication reducing sensitivity. That reminded me, I think I asked a similar question regarding stall guard a couple years ago. Forgot until now.
I may experiment with a cheap 2mm lead screw and bang on that to see if it can be tuned. Regardless its probably best to have some form of mechanical fail safe.
Probably not a bad idea for folks to check out this little calculator that quickly gives you force using a ball or lead screw for any axis. It can get nutz with low lead numbers
https://www.lintechmotion.com/sizing/Thrust-Force/thrust-inputs.php -
@3DPMicro Another problem with stall guard is that it can be affected by motor temperature, which can make it unreliable. Dropping the motor current when homing can also be a useful safety feature to implement (and it's free and easy to do).
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@deckingman said in [Is Stall detection a reliable safety feature Dropping the motor current when homing can also be a useful safety feature to implement (and it's free and easy to do).
I use that technique on my Duet 2 micro mill. I'll make a note to implement that in 3.
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One problem I had in tuning stall detection for homing is that I had to lower the current LESS than I was because it would stall too easily. It's a balancing act.
Plus if you intend to use stall detection during an actual job operation you're tuning for a different current entirely.
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i'm in the same boat . my current (not yet implemented) solution is to use 3 optical switches . 2 switches close to the edge of the axis on each side (around 10mm before dead stop) , another switch for homing which will be approx 30mm of the edge , before the "edge switch".
2 edge switches should never be triggered , and will be connected to EMO / power disconnect of some sort .
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double post
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My main concern is the 2 motors getting out of sync (Z axis) or 1 running and 1 not. I recently had that happen on another machine and it tore stuff up big time before I could stop it and that's what got me thinking. This new build has way more power but that's an unwanted byproduct of trying to have an insanely accurate and repeatable Z
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stacked optical switches seems like a viable option?
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@hackinistrator said in Is Stall detection a reliable safety feature w/ MB6HC:
i'm in the same boat . my current (not yet implemented) solution is to use 3 optical switches . 2 switches close to the edge of the axis on each side (around 10mm before dead stop) , another switch for homing which will be approx 30mm of the edge , before the "edge switch".
2 edge switches should never be triggered , and will be connected to EMO / power disconnect of some sort .
That would only work close to "home" though. Correct?
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@Phaedrux said in Is Stall detection a reliable safety feature w/ MB6HC:
stacked optical switches seems like a viable option?
Only close to "Home"?
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@3DPMicro NOPE.
Not safe. At all.
put some safety switches on your bed. -
@3DPMicro close to axis limits .
i don't have anything else that can crash , except axis limits ( for each axis) . well maybe the printed part in case of warping , but that's nothing serious . -
Thanks. I may implement the dual switches . Looks like there are solutions except for if 1 motor moves and the other doesn't say if it was at the bottom of travel going towards home. I think I have an idea that can take care of that mechanically/electrically. If it gets too far out of wack it will open/close a circuit that kills power or activates an emergency stop
