Centroid Community CNC Support Forum

vtcnc wrote: ↑Wed Dec 30, 2020 1:42 pm I'm confused, page 192 of the CNC12 manual indicates that the M51 command to enable C-Axis is a feature.

https://www.centroidcnc.com/centroid_di ... -v4.14.pdf

It is. You can assign an axis to be a C axis.
But how you mechanically implement that is up to you.
I believe the original poster wanted to use the same motor to be a spindle and a C axis. That means that the control would have to stream step signals to drive the axis motor as well a spindle motor (The RPM limitation could also be the pulse stream the drive would accept along with max voltage the drive could accept) but then TURN it into a C axis when commanded.

At this time, and I confirmed this with Centroid. ACORN can not do this. It is on their list of things to do.
But remember, its not just as simple as taking a servo motor and driving a spindle. You also need to lock that spindle in position and NOT rely on the axis motor to hold position against tool cutting pressure.

Right now, the user has to use a drive/axis motor to position the spindle (along with a brake mechanism) and a SEPARATE spindle motor to utilize the C-Axis feature

Marty

martyscncgarage wrote: ↑Wed Dec 30, 2020 2:02 pm

vtcnc wrote: ↑Wed Dec 30, 2020 1:42 pm I'm confused, page 192 of the CNC12 manual indicates that the M51 command to enable C-Axis is a feature.

https://www.centroidcnc.com/centroid_di ... -v4.14.pdf

It is. You can assign an axis to be a C axis.
But how you mechanically implement that is up to you.

Marty

I see. OK, thanks for the explanation.

martyscncgarage wrote: ↑Wed Dec 30, 2020 2:02 pm

vtcnc wrote: ↑Wed Dec 30, 2020 1:42 pm I'm confused, page 192 of the CNC12 manual indicates that the M51 command to enable C-Axis is a feature.

https://www.centroidcnc.com/centroid_di ... -v4.14.pdf

It is. You can assign an axis to be a C axis.
But how you mechanically implement that is up to you.
I believe the original poster wanted to use the same motor to be a spindle and a C axis. That means that the control would have to stream step signals to drive the axis motor as well a spindle motor (The RPM limitation could also be the pulse stream the drive would accept along with max voltage the drive could accept) but then TURN it into a C axis when commanded.

At this time, and I confirmed this with Centroid. ACORN can not do this. It is on their list of things to do.
But remember, its not just as simple as taking a servo motor and driving a spindle. You also need to lock that spindle in position and NOT rely on the axis motor to hold position against tool cutting pressure.

Right now, the user has to use a drive/axis motor to position the spindle (along with a brake mechanism) and a SEPARATE spindle motor to utilize the C-Axis feature

Marty

To be clear on the spindle / C axis combo switchover :

Marty, I would read your sentence revised as follows-
That means that the control would have to stream step signals to drive THE SAME PHYSICAL MOTOR as a spindle motor in 'plain' turning mode, and as a Rotary Axis in C Axis mode.

Note that the use of a brake on the 'now' C axis is not necessarily as you state - first, it depends on the holding torque capability of the 'servo', and second, in lieu of a Y axis, many, if not most, part milling operations require coordinated motion between C axis and X/Z axis - eg, milling a HEX onto the end of a shaft in the C axis chuck , with the mill cutter axis in the same plain as the C axis - milling a course pitch thread or helix, etc.

I am trying to see if LinuxCNC may do what I wish - it does have all the hooks and functions to do so, but requires deep linux knowledge, ability to modify and add routines yourself, etc, etc..and THAT is a BIG journey and I am suffering! - I am close to just procuring the Acorn and getting the lathe going to the extent the Acorn permits, and hope Centroid adds the extra features later! The Acorn is a very polished package, and my project is about the lathe, NOT about making a controller!

Thanks to all who commented.
Regards
Joe

Hi Joe,

I'm keenly interested in your project as I'm researching to do the same thing you are. I have access to a Hardinge HC headstock and bed and plan to fit up an XY stage with Clearpath SD units. I'm kind of stuck on this same spindle motor selection problem as you.

I guess I'm fundamentally misunderstanding what Marty is saying. I read his explanation as you interpreted it. Acorn cannot do plane switching using the same spindle motor that serves dual duty (plain/C-axis). But the Acorn documentation suggests it can in the marketing literature and Marty suggests that the C-Axis can be utilized if using seperate motors.

So my misunderstanding in WHY this is the case is apparently in not grasping why a servo motor timed to the spindle can't be utilized as the C-axis. I THINK/GUESS that it is because the M spindle commands in the g-code are not telling the C-axis to take step and direction which is what the Acorn can do, at least according to the documentation and how I interpreted Marty's answers.

Looks like a small microcontroller project. 0-10V analog in along with spinFwd and spinRev and generate a step and direction pulse train. Use some isolation relays to switch this circuit in when spinEnable is on, and switch in axis4 pulse and dir when spinEnable is off.

Acorn can't drive a servo motor in position and analog spindle mode...YET (On Centroid's laundry list of feature enhancements)
You can assign any axis motor as a C axis. But YOU have to devise a way to couple it to the spindle.
If you need to home the spindle, add a sensor to it perhaps. You could write a G code program to home it before using the C axis...

Dont shoot me but was the feature to use the step/dir as both an x drive and spindle ever implemented?

Navanod wrote: ↑Thu Mar 17, 2022 10:06 am Dont shoot me but was the feature to use the step/dir as both an x drive and spindle ever implemented?

sorry, its still on the list. we've been concentrating on Plasma with a few Mill,Lathe,Router small improvements and fixes tossed in there for the last months now.