Hitachi m12vc weird behavior when attempting to touch off

[rlrhett]

I have a Hitachi based system C10 bob, and Gecko controllers. If I connect the leads for a touch probe (doesn't matter if I put ground or hot to the bit) and the router is plugged into the electrical outlet the z axis motor starts going all stutter and stop. Eventually it drops the router down and interferes with the probing operation.

If I unplug the router from the power it behaves perfectly.

What is up, and how can I fix it? It is a pain to constantly have to unplug the router every time I have to touch for z.


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[wizard]

Sounds like leakage to the spindle. This could be a serious problem. In any event is the router grounded? If you gave a millimeter it might be worthwhile to to check for a potential between the shaft and the rest of the frame. Another possibility is some sort of ground loop.

[123CNC]

Agree with Wizard. Is your Hitachi power source plugged into the same supply circuit as your controls, esp. the C10 BOB? If not the same circuit, or potentially more problematic if they are each on separate legs of the 220 V main, you will likely see noise or interference as you have described. Lastly, is your touch probe cable shielded and routed separate and as far as feasible from the 110 line to your router?

[wizard]

I'm past time to make a correction but in my first post millimeter should be MULTIMETER. Sometimes autocorrect does more harm than good.

[rlrhett]

Eeeek. Sounds awful. I'll put a muti meter to it, but my guess is that the thing is NOT grounded. If it was, I assume I wouldn't need to attach a negative lead to the bit. I could just have a positive on the touch plate.

I assume they are on the same 110v circuit. I don't have that many circuits in my garage. I'll try moving to different outlets and see if that changes anything.


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[john-100]

Hi rirhett



is the m12vc router double insulated ( just live & neutral connected ) or does it have a 3 core mains cable mains connecting the ground/earth pin to the exposed metal ?

did you connect the touch probe common to +5v on the input terminal block or one of the C10 ground terminals ?



since the C10 breakout board doesn't have any opto-isolators on the inputs

you may have formed a ground loop by connecting the breakout boards ground to the router spindle ground

or if you connect the +5V common to the spindle you could be shorting the BOB's +5V supply to ground at worst or possibly injecting AC currents into the + 5V

more details on how the touch probe is connected to the C10 input will help


if the router is double insulated then its likely there is a small AC voltage on the spindle due to a capacitor in a RF noise filter connected between the motor body and the live mains supply !
'
(leakage currents due to Europe's noise filtering requirements is a growing problem
the UK , USA , Canada and the rest of the world puts up with it to get CE approval to export to Europe
with IT installations the leakage current from multiple switch mode adaptors can be a shock hazard - guess how I know ! )

provided you can confirm the Router is not faulty
you could use an opto-isolator to connect the touch probe to the C10 input




John

[rlrhett]

Ok, tested with a multimeter. Potential between bit and router casing is about 6-9 ohms regardless of whether it is plugged in. I'm testing on the shaft AND at the screw where the green ground lead from the power cord is attached. The probe leads are connected to the 15 pin for ground and the 5v pin right next to it. Are all the pins labeled "5v" common? I didn't know.

The router has a three pronged plug. As far as I can tell, the BOB is plugged into a socket that is a different circuit than where the router is plugged in. The probe wires are not shielded. I opened up the router and confirmed that the green lead from the power cord is attached to a screw in the casing.

Does that help?

[john-100]

Hi rirhett

yes you have five common +5V terminals with the five inputs (pins 10 , 11 , 12 , 13 , 15)

but you have two common ground terminals for the outputs ( pins 1 , 14 , 16 17)

and six jumper selectable common terminals (all +5v or all ground ) for the eight I/O pins
that can be set as eight inputs or eight outputs ( pins 2 to 9)



with the router spindle connected to the mains ground ( via the spindle bearings )
you need to either use an opto-isolator or use an insulated touch probe to break the connection
between the router spindle and the C10 breakout board

what type of limit switches are you using ?
and are the connected to a common +5V terminal or one of the ground terminals ?


John

PS

just found this board with 2 opto-isolators - https://www.sparkfun.com/products/9118
may be an answer if your not into building your own board