Centroid Community CNC Support Forum

Looking to retrofit a CNC lathe to get C axis indexing and also C axis to X axis / C axis to X+Y axis synchronizing capability.
Not finding info on the forum on whether Acorn 4 and current CNC12 would give me these abilities/how to implement this.
Looking to use the existing 1000 ppr spindle encoder and a vector VFD (Mitsubishi FRA-700 with FR-A7AP card).
Would I need to go to Acorn 6?
Would I need to go to AllinOne/Oak?
Thanks
Joe

Your are not going to be able to do a C axis with a normal induction motor and variable frequency drive. The few users that have created C axis operation have used a clutch and additional servo or stepper drive for the C axis and a normal induction motor and VFD combo for the regular spindle drive.

There are a few threads in the forum on C-Axis implementations.

Acorn/Acorn6 if you are going to use steppers or Hybrid servos. AllIn1DC for DC servos, or Oak for AC servos.

You need a servo that could be switched to position mode with PUL/DIR to have a C-axis with Acorn, or a second drive with clutch for C-Axis.



Uwe

Thankyous to Tblough and Suntravel for their helpful replies!

The search term that seems to bring up the relevant posts which I was not finding in the Centroid forum is " C axis clutch "
and then you can figure out what you want to do for the mechanical part of the C axis implementation:
- position C axis only
- position and lock
- position and rotate under high milling forces
You can investigate how others have done it: Haas with separate servo motor (hydraulically engaged?) to a large spur gear or Suntravels PM lathe with Mayr Robatic electromagnet clutched servo motor using toothed belts; somebody did air clutch and others did manually engage, like back gearing on a manual lathe. Here's a good thread to start the thinking: https://centroidcncforum.com/viewtopic. ... cee#p71785

Then there's also the software implementation (search C axis https://www.centroidcnc.com/centroid_di ... -v4.20.pdf), which seems somewhat clear.

In Acorn lathe hardware, I believe the C axis stepper would become one of the four controllable axes (X Z C). You switch somehow between that axis for C axis control and spindle normal high speed control.

Here is how I build it for my lathe.

https://centroidcncforum.com/viewtopic. ... ayr#p65389

Setup in the V4.99 software, but will update it to V5

https://centroidcncforum.com/viewtopic.php?f=67&t=8445

Yes with M51 you switch from spindle mode to C-Axis mode implementation for Acorn / Acorn6 is best in the current Version >4.99

Uwe