Probe Z on steel table, vice & part

Hi all, this is my first post, so sorry if this has already been covered elsewhere.
I have the journeyman 50. I have the upgraded water cooled 2.2kw spindle & VFD (not wired to the main controller)
So I have a metal framed table, metal vice, holding an aluminium part (ALL CONDUCTIVE)
I’m having issues with the probe Z. This is obviously due to the entire setup being conductive, so I changed the default setting from “normally open” (for non conductive materials) to “normally closed”.
This still did not work for some reason (the tool went UP & warning on controller).

I then put packing tape on the touch probe base to stop the electrical connection through the part, vice & table etc. It worked 1-2 times, so I thought it was fine.

I cleaned the machine & today it is not working again (tool goes up, with warnings etc.)

Has anyone else seen this issue before?
& most importantly, is there anyone here using an ALL METAL SETUP?
& how did you achieve probing Z with this setup?

I understand I need to stop the electrical continuity, any tips for this?
Or am I thinking about this in the wrong way?

I appreciate any help from you guys, & apologise if this has been covered elsewhere.

I can make a video of the entire process if needed.

Cheers guys & thanks heaps for your time & suggestions.

Hey AntMan,

I assume you are talking of Buildbotics.com-derived Onefinity CNC Controller.

Yes it’s true, it has already been covered and you would find it in the forum with the search function:

  1. Because your spindle is grounded, then you need only the wire leading to the 3-Axis Touch Plate. Unlike when using the router, you now do not need the magnet end of the touch plate anymore. But in most cases the cable is wired the wrong way around. See here for details.

  2. Be absolutely sure that your spindle is grounded through the fourth (PE) wire of its motor cable, otherwise you have a strong safety problem. Although the machine chassis has to be grounded, including all moving parts, the spindle should NEVER be grounded through the chassis! The only correct way to ground the spindle is through the PE wire in its motor cable that is connected to VFD ground (⏚) (usually in its grounded control cabinet), and from there it is connected to ground in the wall outlet or wall box.

    Note that even if PE wire and cable shield are both connected to ground, they serve two different purposes. PE is crucial for electrical safety, and shield cannot replace the PE wire.

    If you bought a cheap Chinese spindle, you should also be sure that in the spindle the PE (fourth) pin of the spindle socket is actually connected internally to the spindle housing, as seen here. You can check this with a multimeter (set to ohms/resistance, the resistance between the PE wire and the housing of the spindle must be close to zero).

:white_check_mark: IMPORTANT NOTE: I would strongly advise against making your own spindle cable without reading this document:

See here for details:

Welcome to the forum!

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Hey, THANKS SO MUCH for such a fast & helpful reply !!!
I will go over all this over the weekend & hopefully fix all the issues you’ve mentioned.
You have no idea how happy this has made me, it was holding up my new product production.
I will definitely owe you a huge favour or bottle of wine once it’s working etc. All the way from Australia!!
I’ll let you know how it goes, & again, thank you SOOOOOOO much for this info & help.

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Can we see a picture of your set-up? Sounds pretty cool!

G’day MakerJace, yes sure, I will actually take some video of the entire machine once I’ve got it all setup etc (busy with family stuff).
Thanks for your question mate, I’ll get to it asap.

Cheers & have a great week!

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Hi again,
So I tried the following -

  • checked spindle earthing etc - was correct (by electrician)
  • tried probe Z with & without the magnet & with ‘normally closed or open’ in I/O settings
  • tried all above using the opposite inlet on console (as in pic with red or green)

None of this worked, & I restarted the console each time.

I then put packing tape under the probe base to cut the circuit & it worked again with original ‘normal default’ setup.

Is there anything else I can try? Do I have a faulty console? it should just be a case of changing it to ‘normally closed’ yes?

This is really frustrating & doing my head in.

Also, should the console completely shut off when I push the emergency stop… what should happen?

Also, my console does not ever shut down completely… it just hangs… forever… I have to actually unplug it from mains to shut down… is this normal?

Appreciate any help.

Cheers.

Do you have a volt meter?

I’ve really not thought much about the touch probe before, since mine has always just worked. Though, the grounded spindle implies that there’s a pull-up resistor pulling the touch plate high (normally high input), and it is then grounded through contact with the bit.

With a volt meter, you can check the voltage drop between the touch plate (when not on your work piece/table) and the spindle. If the reading you get is different than the reading when the touch plate is in contact with the work piece, it won’t work without electrically isolating the touch plate.

I dont have a Journeyman anymore, but from what I remember, the e-stop doesn’t shut the controller down. Seems like there should be a reset button to hit after releasing the e-stop button, but I dont remember. Never really e-stopped mine.

Dan

Another option could be electrically isolating the vise (and therefore the work piece) from the grounded table. Put a rubber mat beneath it and use non-conductive fasteners to hold it to the table.

Could also use rubber pieces to isolate the work piece from the vise…

The problem you’ll run into with the conductive touchplate on a grounded work piece is that, as soon as the touchplate touches the piece, the touchplate has been grounded. As far as the Onefinity controller is concerned, tge touchplate being grounded means that it is in contact with the bit on your spindle.

Dan

Coat the bottom of the touch plate with plastic tape.

You might have to tell your controller that your touch plate is a bit thicker than it now thinks.

Or mount the vise on a piece of wood or plastic.

Hey AntMan,

please could you do the following:

  1. the correct setting for “probe” on I/O page is “normally open”.

  2. Put your XYZ Touch plate somewhere where it does not touch something grounded (for now).

  3. Be sure the magnet end of the probe does not touch something but is out of the way.

  4. Click “Probe Z” on the control pane, and take the XYZ Touch plate into your hand, approach it to the bit in the spindle until it touches it.

What does the popup on the screen say?

If you put the aluminium touch plate into contact with a grounded surface, and the bit that is supposed to close the probing circuit is also grounded (as it usually is with converting to a spindle), the probing circuit is of course thwarted. However, I wanted to come to that in the second step. When using grounded workpieces it requires a modification of the touch plate.

This is unlikely.

No, since you don’t open a circuit on probing.

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Hey AntMan,

This depends on which estop button yo mean, the virtual on the display, or the red button on the controller box.

If you mean the red/yellow symbol on the top right corner of your display, then you enter the “estopped” mode. All motors are stopped, including the spindle (if it is correctly connected to the controller, it is put in Safe Torque Off mode) or a router (if it is controlled by a relay on 'tool-enable" function (via pin 15 of 25-pin I/O port)).

Unfortunately, on the buildbotics.com derived Onefinity Controller, when entering the “estopped” mode this way, your program is stopped and cannot be resumed, and all positions and offsets are lost (however you can find and re-create them in the log file).

On the other hand if you mean pressing the big red mushroom-shaped button on the black Onefinity Controller box, then only one thing happens: The power to the Raspberry Pi 3B and the AVR mainboard including the stepper motor drivers inside the Onefinity Controller is suddenly cut. The stepper motors become powerless, but if no special precautions are taken, the spindle and the router continue to run. If you have a Z axis with a spindle that comes down with gravity when stepper is made powerless, you have a nice hole in your workpiece or table since the spindle still runs.

But this is still a very simply way to implement a safety stop. If you want to know how a real safety circuit works in the industry when using a VFD and a spindle, see here.

If you want to know more about Emergency Stop Categories see here and here.

One of the causes why this can happen is when the controller has its power off, but is backfed with a 5 V voltage from the touch display via a USB port. It then reboots after shutdown again, but the power it receives this way is not enough to start the entire system so it leads to a system error with kernel panic. You can avoid this with a piece of hardware that prevents a 5 V voltage from attached USB peripheral devices to be backfed to the Onefinity controller. See here for more information:

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