caxis.comp - How to freewheel axis/spindle?

I'm using a component authored by Andy Pugh to control my lathe's main spindle as both a C-axis and spindle.  Comp attached, and I believe this was the last version Andy and NoJo worked out via the forum a few years ago.

NOTE - this component treats the spindle as an axis until a spindle command is issued.  This means absent a spindle command, the C-axis is active and trying to maintain a position.  Once the spindle command is done, C-axis re-engages and will return to the last position (within one turn) prior to the spindle command.

I want the ability to disconnect the spindle/axis so I can manually turn it (indicating part/chuck).  Because the spindle motor is a servo, if the drive is enabled and machine is on, the spindle is locked in position when the machine is at rest.

Right now I have a simple enable toggle in HAL that disables the drive directly.  This allows me to turn the spindle by hand for indicating or tightening the chuck.  I can jog the C-axis, but I find being able to manually move the spindle more convenient.

Unfortunately, because I haven't disconnected anything else in HAL, if I rotate the spindle more than about a turn I get a following error and LCNC turns the machine off.  I've had to set the ferror higher than I'd like just to be able to turn it a bit, and I'd really like to tighten it up.

I could use some help figuring out how to disable the motor in such a way that:

• No following error while disabled, regardless of turns
• No caxis.comp errors or accumulation of following error upon re-enable (which would result in a potentially violent attempt by the C-axis PID to eliminate the following error)

Is this something I could accomplish in HAL, or does caxis.comp need to be modified/edited in some way?

@Aciera - 

I had hoped to duplicate your C-axis process back when you were working on it, but my drive doesn't permit on-the-fly mode switching via external input.

Since I don't think I can use orient.comp and caxis.comp on the same joint, I'm thinking about ways to un-home and re-home the joint/axis.  Caxis.comp doesn't re-home or move to C0 whenever the spindle stops - it returns to the same position it was in when the spindle command was issued.

Since I don't need to freewheel in the middle of a program, what do you think about using halui to unhome/rehome the C-axis?

• Freewheel button ON (M-code)
  • set halui.joint.C.unhome
  • Latch encoder reset pin HIGH (to keep it at 0)
  • Amp enable OFF
• (manual spindle rotation activity)
• Freewheel button OFF
  • Amp enable ON
  • Unlatch encoder reset pin
  • set halui.joint.C.home

See any major issues with the above before I try testing it this evening?