Mill with auxilarry spindle

I have a three axis gantry router using stepper motors on the three axes and wish to use the A output to drive an auxiliary spindle through a stepper motor. The router spindle is driven through a VFD.
I need the auxiliary spindle to run at a controlable steady rpm (and also be controlled by at variable speed through the g-code if possible).
The machine would then run as a router lathe.
Despite searching i can't find anything that indicates how to set up STEPCONF for this purpose or how to drive the stepper.
Is it possible to use a stepper motor for this and if so how do i do it?
The nearest i got to understnding it was
Help will be much appreciated.

If you just need a step rate and direction set by a gcode command its
certainly possible in the hal file but I dont think the stepconf knows how
to do this.

Basically you set up a new step generator running in velocity mode
and connect the stepgens velocity command to perhaps a analog output pin
set by a M68 gcode

You don't need to use M68 as Versions 2.8 and 2.9 support multispindle configurations.
So you can control the speed using M3, M4 and S commands but you will still need PCW's methodology to set stepper speed.

See:
linuxcnc.org/docs/devel/html/gcode/other...ec:set-spindle-speed
linuxcnc.org/docs/devel/html/gcode/m-code.html#mcode:m3-m4-m5

You should be able to use some hal logic on the spindle forward and reverse pins to map to a step direction signal. See
linuxcnc.org/docs/devel/html/man/man9/mo....html#SPINDLE%20PINS
off the top of my head an or2 on the direction pins with the output and2'd with one of the original direction pins should do it.

So its time to learn how to edit your hal file by hand.

You should not need any special direction pin mapping, just use the signed spindle
RPM from LinuxCNC, for example spindle.1.speed-out, and connect it to the stepgen
velocity command, direction will then be automatic.

Thanks for your replies which I'm sure will help. I won't be able to get to work on the issue for a while but I'll keep you posted.

Nice set up. Who was the mill manufacturer?
MArk

I've set up the A axis on the bench and it is now running perfectly in position mode in that i can control it with g-code to rotate at commanded angles and speeds; part way there. I had to increase FERROR to have it run at decent speeds.
However, I'm having difficulty with changing the A axis to velocity control.
I can't find "ctrl_type" in the "loadrt stepgen" section of the HAL file to change. I tried adding it following another post but Linux CNC wouldn't load.
I've studied the references given but the info hasn't penetrated into my grey matter.
Any additional help would be appreciated.
I attach the .ini and .hal files.

The rotational axis is aligned with the y axis and i quess, therefore, should be the b axis and not a. How do i change this?

Thanks

I believe that that is set by the loadrt line when loading the stepgen component. There isn't a pin for changing it while running.

loadrt stepgen step_type=0,0,0,0 ctrl_type=p,p,p,v

Should change the last stepgen to velocity command.

In the hal file there already existed the first part of the line so i added ctrl_type=p,p,p,v but Linuxcnc would not load. I changed the v to a p and it loaded. I understand the default is position control so i guess the hal file is configured for that.
Looking down the hal file for the a axis i find this.

setp stepgen.3.position-scale [AXIS_3]SCALE
setp stepgen.3.steplen 1
setp stepgen.3.stepspace 0
setp stepgen.3.dirhold 36000
setp stepgen.3.dirsetup 36000
setp stepgen.3.maxaccel [AXIS_3]STEPGEN_MAXACCEL
net apos-cmd axis.3.motor-pos-cmd => stepgen.3.position-cmd
net apos-fb stepgen.3.position-fb => axis.3.motor-pos-fb
net astep <= stepgen.3.step
net adir <= stepgen.3.dir
net aenable axis.3.amp-enable-out => stepgen.3.enable

This seems configured for position and may need re-configuring for velocity. If that's the case how do i go about it?