Speed modifier for single axis (extruder)

Hi everyone,
Hope you are all doing well and safe! A quick question: at the moment I'm working on a LinuxCNC powered 3D printer. I was wondering if it is possible to modify the speed of a single axis (the extruder) while printing (so while a gcode file is being read) without touching the other axes. Has anyone tried something similar before?
Thanks,

Amedeo

Hello Amedeo,

Yes, we are currently using the A axis in this way. the secret is to use the speed mode for the A axis and delete the following errors events.
A possible solution here:

setp hm2_[HOSTMOT2](BOARD).0.stepgen.04.control-type 1 ##set the control type to velocity mode
setp pid.6.enable 1
setp pid.6.Pgain 0
setp pid.6.FF0 0


net motor.04.loopback <= joint.4.motor-pos-cmd ## note command is looped back to feedback
net motor.04.loopback => joint.4.motor-pos-fb ## so no following errors are possible
setp pid.6.enable 1

the PID FF1 pin could be linked to your variable extruder scale source

Hi Alessandro, all,
Thanks for the quick reply. I'm attaching the ini and hal files for the machine. As you can see, the extruder axis is set up with a closed loop control using an optical encoder mounted directly on the stepper shaft. The control is implemented through a PID loop, so the PID parameters are already set.
Maybe the spindle solution is better for this case?