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Probotix Touch Plate help (CNC)

8792 Views 51 Replies 9 Participants Last post by  4DThinker
For those of you that own a Probotix CNC and use LinuxCNC, if you have their touch off plate could you tell me what color the Probe indicator turns when the plate touches the bit? I'm trying to debug why mine doesn't work but don't know how it should work if hooked up properly.

At the moment my probe icon is blue, and doesn't change when I touch my bit to the plate. When I tell LinuxCNC to set Z with the touch plate my router just moves up until it hits the limit switch then shows me an error. To me that seems as though I've already got a short somewhere between the parallel port and the touch plate.

Any help greatly appreciated.

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The icon should be gray until contact is made and then it turns blue.
What happens when you touch the alligator. Clip to the puck surface? That should simulate a touch off.

Did you read this?

Your link lead to a page with no text, but I did read all the info I could find about the Z touch off on their wiki.

I just unplugged the cable I made and restarted LinuxCNC and the probe icon is still blue.

I had a look again, and apparently I had my ground and touchpad wires backwards. After switching them and re-connecting the parallel port it seems to work. I didn't think it would matter as all it would need was a connected circuit to set off the Probe indicator, but the CNC frame is ground and so when I connected the alligator clip to the bit that alone closed the circuit. Now all I need is the touch plate connected to pin 13 and the Z touch-off routine works.

If anyone has continuity from the frame through the router down to the bit then no alligator clip or magnet attachment is needed. A single wire from plate down to the parallel port would do.

I've also seen that you can probe to touch off the other two (X and Y) directions somehow. I'll have to do a little more research though to figure out how.

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We were hoping that all routers would have continuity to the frame, but they do not.
Might be nice/useful to assemble a list of which routers do have continuity from bit to body. The one I use is a Dewalt DW618. We use the same model on the Meteor and Nebula we have in our college shop.

Welcome to the forum @probotix.
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For anyone who does not already have a touch plate, here are a couple photos of my homemade one.
A chunk of aluminum bar from my scrap bin.
Drilled a 5/32" hole in the side to receive the audio plug.
Used their configurator to enter how thick the bar was (.367").
Ran a 2-lead cable from the router to the controller through the cable chain and using an old 25-pin cable end got it wired up to plug into my second parallel port.

I will be making a small rack to hang it off the side of the router clamp once I figure out the best way. It can't touch the frame while not in use or the Probe icon will stay blue.



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We were hoping that all routers would have continuity to the frame, but they do not.
That's something I never would have thought of . I hope most spindles do?

Welcome to the forum Probotix
So far I've been able to add buttons onto the LinuxCNC interface for X and Y touch-off using the puck. I've made copies of the o102.ngc subroutine for X and Y (o103 and o104) but not yet figured out what else I need to edit to get them to actually work.

My hope is to jog the bit to within 1" of the X or Y edges, put my touch plate on its side between the bit and edge, then have the bit probe in the +X or +Y direction until it touches the plate. Then set X or Y zero to their position + the plate thickness. Then have the bit move back one inch.

Still working on it.
If you haven't already, you need to go into your .ini file and under the HALUI section, add MDI_Commands for each subroutine.
Think you will figure it out when you see the others. Should look something like this:
Just add yours at the bottom. Must restart PC after making changes. Always a good idea to make a backup copy just in case.

I saw and added the MDI_COMMAND lines. Not enough to make my interface buttons work. There was also an entry for o102 in one of the .HAL files for Ztouch/Zpuck which I'm guessing is needed too for the X and Y o103 and 0104 subroutines. I added what I thought might work but then LinuxCNC wouldn't start. Had a backup fortunately so back two steps to a working version.

In my younger years I was a pretty good programmer, but turning 60 in a month seems to have robbed me of my youthful ingenuity. I'll figure this out eventually though.

I know linuxCNC has been around a long time, and evolved greatly to the point it is now. There are a few web-based g-code CAM apps in the early stages of sophistication which pale to the capabilities of linuxCNC yet prove I may not be the only one who ponders making a CAM program from scratch. If only so I would KNOW what the secrets are to making it have all the features I want.

I've been comparing the accuracy of setting Z with a slip of paper or using the touch plate. In both cases I'm setting Z at a level where the board just barely slips under the bit but doesn't lift up at all. Using the touch plate is much quicker though if it can be trusted. The speed comes from keeping it always near the bit to be set beneath it/atop the work at the same time a bit is changed. I have more trouble setting X or Y against the side of the workpiece as the wrong rotated position of the fluted bits can make for a noticeable error.

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Hmmmmmmm - I guess this makes my playing card technique obsolete. And I still got about 45 cards of the original deck left.
I thought you already had your buttons working... .Hal files tie your xml together to make them work. Not sure I can help you without having your xml and Hal pin numbers and names.
Have you tested your subroutines? If you go to the MDI tab (F5) and type in: o103 call, that will run subroutine o103.
Not at my computer right now, but check out the LinuxCNC manual, they have examples for buttons and subroutines.
Hmmmmmmm - I guess this makes my playing card technique obsolete. And I still got about 45 cards of the original deck left.
You gotta get with the program. :smile:
Yes the subroutines work standing alone. I have the buttons showing up on the linuxCNC screen but they don't do anything when clicked on.

Still working on it.
This is what I have for my Z puck. Are you using the same input as Z or do you have additional inputs.

I can't tell you what parport pins or names to use, but the context of adding a button needs entries in all of these 4 places (.INI, PYVCP.XML, POSTGUI.HAL, .HAL).

In the POSTGUI.HAL file, where it says "mdi-command-03", the number has to be which number MDI-COMMAND it is. This one is the 3rd command (starting counting at 0). Make sure to get your syntax correct or you will get errors.


# add halui MDI commands here (max 64)
MDI_COMMAND = G53 G0 X24.0 Y48.0 Z0
MDI_COMMAND = G53 G0 X24.0 Y4.00 Z0
MDI_COMMAND = G10 L20 P0 X0 Y0
MDI_COMMAND = G64 P0.001
MDI_COMMAND = G64 P0.010
MDI_COMMAND = G64 P0.040
MDI_COMMAND = G17 G20 G40 G49 G54 G90 G64 P0.01 T0 M6


<!-- ZPUCK -->
<text>"Set Z Origin w/ Puck"</text>


net z_probe pyvcp.o102 halui.mdi-command-03


# set up the probe input for the tool sensor and the z-puck
# the tool sensor is normally closed, the z-puck is normally open
# we will put them on two seperate pins and 'or' the two signals together
setp debounce.2.delay 100
net deb2.0 <=
net deb2.1 <=
net tool_length_in or2.6.in0 <= debounce.2.0.out
net z_probe_in or2.6.in1 <= debounce.2.1.out
net probe-in motion.probe-input <= or2.6.out

Hope this helps!
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I've got essentially the same in my files, Dave.

I've added
MDI_COMMAND = o103 CALL [2] and
MDI_COMMAND = o104 CALL [2], but I'm not sure what the [2] does or if it needs to be different for each subroutine.

I've added:
<text>"Set X Origin w/ Puck"</text>

<text>"Set Y Origin w/ Puck"</text>

all under <!-- ZPUCK -->, but they may need to be under their own heading. They do show up as buttons on my LinuxCNC screen though.

LinuxCNC has crashed when I've added anything to the POSTGUI.hal file.
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I m not sure what the numbers are for either, but do think they need to be different.
Can you post the error message or email to me? Usually about the last line gives you the answers.

Are you using the same pin as Z?
I think the call numbers need to be different.

Can you post the error or email it to me. Clue is usually towards the end.

Are you using the same pin as Z?

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