Your e-stop is not in the right place as shown it is more of a kill switch and your ESS and Mach will not be happy

Rob

I most definitely did not ground the -v/0v of the power supply to the chassis 220vac earth, or at least not intentionally.
I measured the voltage between the C25 ground and the grounded spindle and it is 0v.
I'll check in the morning... must sleep now.

it should be 0v sitting there, as rob say your E stop is a kill your stepper driver switch you just need it for the 5vdc power supply no power to ESS or C25 no motion.

killing the power to the stepper motor when they are under load can cause a power surge back to the stepper driver and magic smoke will come.

now just for fun touch the wire attached to the plate to the clip there may be some stuff on the plate giving a bad contact. the voltage is within the amount that it needs to work.

also just check for continuity between plate and clip with no power to the machine.

one other thing have you changed the pin from active high to low or vices versa the red x to green tick

I went through and checked continuity:
0 continuity between chassis grnd and C25 grnd pin
0 continuity between chassis grnd and C25 +5v pin
20.5M resistance between chassis grnd and table/spindle/tool
0 resistance between C25 pin 15 (probe signal) and touch plate
0 resistance between C25 grnd and clip
0 resistance between C25 pin 15 and C25 grnd when clip is on touch plate
Measured voltages:
4v between C25 pin 15 and grnd when probe circuit open (clip not touching plate)
0v between C25 pin 15 and grnd when probe circuit closed (clip touching plate)
0v between between chassis grnd and C25 grnd
0v between between chassis grnd and and C25 pin 15
0v between between chassis grnd and C25 +5v pin
I'm going to re wire the Estop as soon as I post this. Thanks for the heads up blockhead and Rob

rob the C25 manual have a look http://cnc4pc.com/Tech_Docs/C25R3_1_USER%20MANUAL.pdf

by looking at the C25 manual, you can have switches connected using the 5v of the board to a pin what is simple, the prope touch plate needs to be grounded to the C25 board it has the ground symbol like you said you have it connected to the ground of the board

Quote

Why not use a crocodile clip onto the tool when you want to use the tool offset / probe function

I am using a crocodile clip on the tool or when the tool is to big for the clip I clip it to a bolt head on the spindle mount, but for the testing I have been clipping to the tool. To add a little more to my grounding theory if I touch the ground to the tool in the middle of the zeroing macro I can feel the machine react to the contact, not much, but there is something happening and this is long before the tool reaches the touch plate.

Quote

Then put the 5v (pin 13 or 15 input..forget which one you are using) to your insulated calibrated height block.... (You could use a piece of blank PCB (printed circuit board)....

you just described my setup as it stands now, although my circuit board is loose so I can move it around to the work piece.

I still think you have a grounding issue with a ground loop somewhere as there should be no reaction if you touch the tool to the ground at any point ^^^^^ (read the quote / statement above from an earlier post).

Yup I've been having a look at the manual...thanks

And I've put a post on the Warp9 website (suggest you register and have a look for yourself).
http://www.warp9td.com/
(Andy should be working for a little while longer yet US time)


Rob

This scares me, for the last week I've been chasing down this bug of why the auto tool zero was not working with the help of all of you. Going through all these iterations but ultimately changing nothing on the machine, settings, wiring, or otherwise. Out of frustration today after work I went into the shop to see if I could find that elusive ground loop we all know is there with a voltmeter and ran the auto zero routine to see if there was any voltage between the C25 grnd and the chassis grnd while running the routine...none, so just for kicks I let the machine run through the whole routine and....it worked?!?! I repeated it 5 times and 5 times it worked. How is this possible? Like I said this really scares me, for no rhyme or reason it started working so I guess  for no rhyme or reason it could stop working. Ahh well I guess I shouldn't look a gift horse in the mouth.  We'll see if it's working tomorrow. Thank you all for your patience and help. I'll probably need it again soon.

Don't be scared by any of this treat it as an adventure... You never know what's around the corner...  Have a healthy respect for it and safety as the machine has no brain (fingers out of the cutting area etc)... Some days stuff works... Some days not... As Edison said " I have not failed.  I have only found 1000 ways not to do something "

Glad to hear its working.

May I ask..
What type of network cable are you using (any markings on it)... Is it shielded? ... Cat6?

Does the network cable go directly from the PC to the ESS... Or have you used a lead with a bulkhead connector?

Rob

yer it sounds like you have a RF problem as well. having a high grade ethernet cable helps. if this happens again shut everything down in your shed and only have a fm radio going no lights nothing turn the machine on and if the radio becomes stackey you have a RF problem from the machine turn it on and off a couple of times to see if it will clear it self.

by having only the radio and machine on you can eliminate the machine quickly as the source of the RF. then if it`s not there you just turn one thing on at a time to it comes back.

I have a random bad RF problem with my big machine, when the RF is there the radio goes all stackey and the machine run like a bag of poo, quite often I can just turn the machine off and restart and it goes away.

and if I stand in line with the radio it goes away as well that's how I know it's from the machine.

Good method there thanks
Rob