Fixing a stepper motor

fmeleard

Hi,
I use the Duet3 6HC to control a PLC on 4 axes.

The equivalent of the Z axis carries tools, and must remain in position in a certain case.

But it is impossible to lock its position, each axis moves correctly, but none is locked in position. My Z axis goes up, then down .... when I would like it to stay in position.

Is it possible to lock a motor in position?

dc42

@fmeleard after you move a motor for the first time after power up it should lock in position subject to the following caveats:

If you use M18 or M84 to disable the axis, or you use M584 to reassign the stepper motors driving that axis, it will unlock.
After there has been no movement for the idle time (default 30 seconds), current will be reduced to idle current (default 30% of normal current). This may or may not be sufficient to hold the axis in place if it is under load. Idle current reduction can be controlled using the M906 command.
On the Duet 3 series (and Duet Maestro), standstill current reduction will kick in a fraction of a second after movement stops. By default this is set to 70% of normal current. It can be controlled using the M917 command.
If you have configured the motors to run in stealthChop mode then the driver may decide to reduce current. So don't use stealthChop mode for axes under permanent load.

fmeleard

@dc42 Thanks a lot for your quick feedback

I don't use M18 or M84
I have applied M917 Z100 and M906 Z1000

The problem remains the same... it stalls a few seconds after reaching its location

fmeleard

@dc42 How to check if my configuration is on stealthChop ?

dc42

@fmeleard said in Fixing a stepper motor:

@dc42 How to check if my configuration is on stealthChop ?

Send M569 D# where # is the driver number.

fmeleard

@dc42 The result :
M569 P0.3
Drive 3 runs forwards, active low enable, step timing fast, mode spreadCycle, ccr 0x08053, toff 3, tblank 1, hstart/hend/hdec 5/0/0, pos 8, tpwmthrs 2000 (0.9 mm/sec), thigh 200 (8.9 mm/sec)

M569 P0.1
Drive 1 runs forwards, active low enable, step timing fast, mode spreadCycle, ccr 0x08053, toff 3, tblank 1, hstart/hend/hdec 5/0/0, pos 520, tpwmthrs 2000 (4.7 mm/sec), thigh 200 (46.9 mm/sec)

M569 P0.2
Drive 2 runs forwards, active low enable, step timing fast, mode spreadCycle, ccr 0x08053, toff 3, tblank 1, hstart/hend/hdec 5/0/0, pos 264, tpwmthrs 2000 (4.7 mm/sec), thigh 200 (46.9 mm/sec)

fmeleard

@dc42 Problem solved

My motors were on 800 ma when they should be on 3A... So, they did not seem to hold the position ...

Now the steppers stay well in place

Thanks a lot for your help