I'll probably forget to hit that manual switch and cause the lathe a crash
I'll probably forget to hit that manual switch and cause the lathe a crash
Hi,
presumably you have an Enable signal for your axis servos, why not common that to the spindle servo motor? Usually the axis servos Enable
when the controller is Enabled. It also common for the Enable signal to de-assert if an Estop event occurs. This would have the effect of
stopping the spindle in an Estop event, and surely that is desirable?
Are you in some way concerned that if the spindle motor is Enabled along with the controller and axis servos, that it might rotate unexpectedly and cause harm?
It does not bother you that the axis servos are Enabled, I mean if there is some fault which allows an Enabled spindle to rotate unexpectedly, then surely
the same fault could cause an axis to move, and is that not dangerous also?
If you are using Step/Dir, or some other pulse input arrangement then the spindle cannot possibly turn UNTIL the controller commands it. There is no safety need
to have an Enable that only asserts when a program is started., unless your installation is that electrically noisy that that a servo drive can Step it's servo on noise
only. If that is the case then the axis servos would be doing the same thing. Do they?
If you are using your servo in velocity mode, ie a free running spindle with the speed determined by a 0-10V analog signal, the spindle ON/OFF signal from
your controller will Enable/Disable the spindle servo motor. No trouble. The spindle can only rotate when the signal is asserted ON, ie Gcode, MDI or manual control.
Craig
Hi,
My axes are steppers and are always enabled but that's totally fine with me. However, the spindle servo is always enabled too (currently) and it is a problem every time I need to chuck and un-chuck a part because the spindle servo is enabled and so the spindle shaft is locked. You know, you need to rotate the chuck to find the chuck key hole and place the key.
Hi,
may I suggest a push button somewhere adjacent of the chuck that de-asserts the spindle servo Enable. That would allow you to push the button so you could manually rotate the chuck,
but instantly have it re-enable and thereby lock up when you release the button.
Craig
I'll try for a while and see if I can live with that.
What causes this behavior? It looks like the drive tries to keep the position. I think in Lichuan servos this can be adjusted with "load inertia ratio" parameter but what is the equivalent parameter to that in AASD drives?
https://www.youtube.com/watch?v=gh7yNLXFMlo
Hi,
are you in Position mode or Velocity mode?
In position mode its not uncommon to have the servo 'hunt' for the exact zero position. This behavior can be modified with the 'Zero Error Window'. If the servo is within
say four encoder counts (the number of counts is programmable) then it ceases trying to get any closer. The fact that the angular position drifts suggests you are NOT
in position mode, or at least if you are you have that much noise happening on the Step signal that the commanded position is varying with noise, most undesirable.
If you are in velocity mode then what you are seeing is noise on the analog voltage input signal.
Craig
Hi,
I set the parameter Pn002 = 2 (called location mode in the manual). I also tried 3 (location/speed mode) and 4 (location/torque mode) but I get no movement with these.
Strange thing is that this happens also when I power-off the machine. I mean when only the servo is powered I turn the lathe chuck with my hand and release then the servo tries to goes back to zero but starts forth and back bouncing. So it's not a pulse from the controller problem.
Hi,
so you are in position mode? You are supplying Step/Dir pules or similar?
If the controller is unpowered, I would have to agree, and yet has must be pulses on the signal for it to move, and those pulses could be noise. Try disconnecting that oneSo it's not a pulse from the controller problem.
signal and try agian.
Craig
Hi,
No, disconnect the Step signal line only, what we a trying to do is eliminate any noise getting in on that line.
Disconnecting the whole plug would disable the whole servo......whats the point?. We need the servo powered and Enabled, but NO input signal.
This will determine if the noise/excitation is external to the drive or internal.
Craig
Yeah sorry. I disconnected the step wire but it did the same.
I also removed the belt and tried but it worked fine. So I guess the spindle and chuck affects the servo as a big flywheel connected to it.
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The same happened in this video but the servo is a different brand.
https://youtu.be/4BOZtKvce04?t=402
Hi Craig,
Found something weird. The printed manual that came with the servo (in Chinese) has a parameter Pn257 "load inertia rate" but the newer English PDF manual (the same you gave me) has not that parameter.
Could that the parameter I need?
English version of the original manual: Index of /files Please search for "Pn257".
https://forum.linuxcnc.org/38-genera...ations?start=0
Yeah, there actually is a Pn257. I set the value to 5 and it looks like it did the job. However that noise you hear in the video comes from the servo and reducing the value eliminates it. I just have to do a fine tuning.
https://youtu.be/4sB3lfHdWRs
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