Ok kind of sounds like there is a problem with your encoder signals. Sure Jonathon (jofriedl) had similar red values and it ended up being poor opto isolation and lots of noise.

Hood

Ok, i'll try swapping the connections over and see if the fault follows, also check my grounding as it all just thrown together on the bench at present.

If no luck, i'll dig the 'scope out and have a look-see.

Hmm, odd - the encoder fault was not there today, maybe a PC reboot or complete shutdown fixed it? Been knocking seven bells out of it all morning and it's not returned so I'm happy with that.

Next I fitted up the Spindle VFD, expecting serious issues with my complex manual/auto speed control idea. I was 100% amazed that I have perfect control of speed from 40rpm to 3000rpm within about 25rpm tolerance! It tells me to choose back-gear or high-gear and high or low speed pulley setting depending on speed chosen.

The only issue it does have is that if it is set for say 100rpm in back-gear low range, and the code calls for 2000rpm in high-gear high range, it will spin up the spindle and then tell me to change gear - this cannot be done without smashing the drive.

I have all the code in SpindleSpeed.m1s - can it also stop the spindle and restart it after pressing enter without wrecking the code flow etc ??

Picture of my bench-mess below Useful to gain an idea of cabinet size too.

A short video here...
https://youtu.be/RiXxmCpC-R0

It is under Special Functions and then Other, should see on right side the Legacy Home Offset option.

Hood

The legacy homing option does not seem to work, I turned it on but although it did stop the axes moving after homing, it also corrupted axis movement in that the Y axis only moved one-way regardless of instruction - the jog buttons only moved one way and the MPG sent it slamming into the stops. Turning the legacy option off again and re-starting Mach fixed the issue.

I'll leave it off for now i think.

Good news on the encoder, maybe just noise getting in with the wiring being a bit hairy and maybe the encoder outs on the drives are a bit weak.

Looks like it is running nicely, certainly a lot better than your taste in music 

Legacy homing worksworked fine for me on Chiron, small lathe, plasma, friends Avon mill and others I know that use it.
Couldnt be you had the Home Off value set incorrectly?

Hood

Ha, the music was the radio, just fills in the quiet bits

It gives me the impression it might actually work

I had the home offsets set so that in normal mode it worked properly - it homed, then moved to where zero really was.
I just turned on legacy homing and when i tried jogging, it only moved one way, tried the MPG and bang it went, good thing i have the limits wired.
Turn off legacy and back to normal - very odd.

So I presume you had a negative value in Home Off if you were homing fully positive?
If so that is likely your problem as when in Legacy mode you enter the value that the axis is away from fully negative.
So say you have 300mm on the Y, you home so the table is towards you (fully positive) you enter 300 into the Home Off and when the machine homes the Y the machine coords are set to 300 rather than Zero, that way Mach knows where the machine zero is.
Hood

Hmm, i'll have to check/try that i think, not sure what is in there, but it does home at the front (max Y+)

I think it may be negative.

To be honest I can't remember how the default (for csmio) home off value works, it was about 3- 4 years ago when I set up the wee lathe with the IP-S so not sure whether it required a +ve or -ve value.

Hood

I just had it set so that it worked in normal mode then presumed turning on legacy just stopped the axes moving?

Seems not.