Spindle Step/Dir servo ramp down before stop on M stop command.

You can do that (using encoder feedback only) but it may compromise
the servo response somewhat.

Thanks for your efforts again Andy-
Its near midnight so tomorrow..
I believe the encoder is working - I have the RPM display GUI set up and it registers correctly - M03 S1000 shows 1000RPM with small variation, etc.
Not sure though if RPM uses the index or the A or B channels of the encoder?
Will verify tomorrow.

Re - the spindle count unwind or reset issue -
Is is not possible or better to just 'home' the C_axis each time you enable the C_axis mode, and then step/dir to the requested angle?, ie, Select C_axis, rotate slowly in only one direction always till index, reset angle count to zero and then G_code to desired angle from encoder count?
I can't think of machining modes where you would need to keep track of the incrementing angular counts...Any polar coordinated 3 axis motion with interceding normal spindle machining operations, with a subsequent C_axis motion would always require an angle setting relative to a known zero, or home angle.

Would be useful to see what a typical CAM package G/M code sequence set might be for such a process, eg, to machine the end of a shaft to a set diameter and then to mill, in axial, C-Axis polar mode , a hex head on that shaft (ignoring all the tool selects, etc - just the motion and selection commands..)

My CAD/CAM package can't do C_axis, but am discussing with BOB_CADCAM folk re procuring their SW and they are prepared to create a post processor for this lathe even before I purchase to assist in evaluating there software as an option, (if I get it working!) - in the meantime they sent me some sample G_Code, FANUC style - this extract to do that HEX in the end of the shaft.

Not sure how LinuxCNC would interpret this...
I would not need 'brake' etc, since the spindle brake is on while enabled ( all the time) and not in motion..

Next Day....
I included your C_Axis mods Andy - the results are:
1. No C Axis appears in AXIS - no C_Axis buttons, no DRO, no reference to a C-Axis that I could find.
2. X Axis still Homes ( moves to home switch, etc, and sets DRO accordingly), and can jog via the AXIS jog screen button
3. Z Axis 'Homes', but there is no axis motion - the DRO position updates to show it is in the home position
4. Trying to jog Z axis via AXIS onscreen button results in a Joint 2 Error ( not Joint 1 , which is the z Axis..)
5 Spindle still works - spins with spindle on command.

The encoder does work -
HAL meter spindle.0.revs shows a x.yyyyz number.
The z decimal appears to increment on every encoder AB chan edge ( 4096 edges, a 1024 line encoder)
The x digit increments by 1 per encoder rotation.

I have checked the additions to INI for spelling, lost hyphens.

In the INI there is [TASK] = milltask - what does that mean? I have not yet found that explained somewhere.

Attached are INI and HAL

Thank You.

forum.linuxcnc.org/10-advanced-configura...servo-spindle#186640

My solution to spindle ramp down is in above thread

Thanks Pippin88.
I did see your solution some days ago already - I was not to keen on doing it with delays - does not really keep pace with different spindle speeds and inertial masses fitted to the spindle, ie, a heavier chuck spins longer, etc...So I did not go that route.

The solution provided by Andy is excellent - it works very well, and is very simple.
I am happy!
Joe

1. No C Axis appears in AXIS - no C_Axis buttons, no DRO, no reference to a C-Axis that I could find.
Possibly because when I said
I meant to sayBut forgot to edit the text after pasting.

I did see that and wonder about it, but only a little...I know too little still to know that I should have known...
Same wondering that took place as to why a milltask is in a lathe setup...

Fixed that and now the C_axis is present in AXIS.

Joe

What Motorcycle is that? A pic maybe>>

Andy, This lathe has been a project in my mind for 6 years till November last year - So what you saw in the photos occurred between November 2020 and now - The aim was (is?) to have a C_axis with a single milling spindle as a live tool, fixed in axial or radial horizontal plain. I like building machines - these machines end up building more machines, and not much else gets made! During this Lathe build, I built an 'electronic' Gear Hobber, A PCB Engraver ( just a small very rigid 3 axis mill with a 25KRPM spindle using an RC plane outrunner motor) an ELS for my EMCO V10 lathe and for my EMCO 14D lathe...etc. All the controllers are ARM cpu based, with all the software in C, done by my Wife..
Also busy converting an EMCO FB2 mill ( I have 3.. yes, I like and have a number of EMCO machines..) from stepper to Clearpath motors at the moment ( with UCCNC...sorry - I have a spare MESA 7i76E, so maybe later. )

- it's all a hobby, I enjoy the challenge, and it it takes another week, a month, or 6 ..there is always some project on the go.

My good wife and I are also heavily involved in a Lion Human/Wildlife conflict management program and we have to go fit some SAT tracking collars on some lions in the next week or three, so my projects simply remain a constant in life's background.

Please do not be pressured on my behalf - I am very grateful that you are taking your own time to help me - I feel quite lost in this while learning and become not a little depressed with it, so your assistance is hugely appreciated.
I also like bikes...
Joe

One day I will get around to using near to determine when spindle is stopped / nearly stopped.

For now I use time delay and 5 seconds (from memory). It is more than enough time for the spindle to stop even with a heavy chuck.

In my case I want to be able to spin the chuck by hand, e.g. for indicating a 4 jaw.

I see that you want the spindle on / held at rest, so different needs.

LinuxCNC can be a bit frustrating when starting out with this stuff. But it it very versatile.