Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: kolias on June 29, 2022, 02:50:35 PM
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Not sure how to wire my home made probe and I came up with the attached wiring.
Do you see anything wrong?
Thanks
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Which wire is the probe?
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I don’t understand the question John, it’s a simple homemade gadget which sets the tip of the cutter 1” above the piece to be cut and then it zeros all DRO’s.
The touch plate is 1/4" thick aluminum plate and the alligator clip is attached to the spindle. So I would say the alligator clip is the probe.
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OK. So the plate is presumably isolated and grounded via the tool or whatever in the spindle, right? That's normal practice.
But your diagram shows the clip on the touch plate so it is permanently grounded! The touch plate should be connected via the pullup to +5V. If you need an alligator clip to do that then fine. Normally you could rely on the spindle being grounded anyway but you might need another clip and ground wire to make sure. I've not found it necessary but it depends on the machine. Commonly the "probe" is a precisely dimensioned thing that's held in the spindle when the machine is being referenced.
Given some reinterpretation your wiring is OK, though I think 120R pullup is a bit low, you will be sinking 40mA odd. 1K would probably do the job.
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Thank you John, yes the plate is isolated and grounded via the alligator clip on the tool. Sorry about my diagram which is wrong but it only shows the principal. I will change the resistor to 1K.
My “probe” is far way from a proper tool but it does the job nicely and have been very happy with it.
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Sorry John but I’m always confused with the pull up/dn and active low/high.
To be on the safe side on the Mach3 input signals screen and Active Low Column, the probe should be set to what? Green mark or Red?
Thank you
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Green tick selects active low.
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Thanks John
Finally the probe wiring is done and the active low is selected. My script is:
Message( "Auto Zeroing..." )
If IsSuchSignal (22) Then
code "G31 Z-3 F20"
While IsMoving()
Wend
Call SetDRO( 2, .367 )
code "G1 Z1"
End If
I still left the “G1 Z1” for now but I will change it the G0 as you suggested. I also installed the 1K resistor.
However on testing the probe, when the Z started to go down I manually lift the touch plate to touch the tool and the Z axis still kept going down (it should have start the retract) and so I hit the E-Stop.
Perhaps the code line "G31 Z-3 F20" may create this? I interpret the Z-3 as it must go down 3”
Any ideas ?
Thanks
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Forgot to mention that on the diagnostic screen there are no lights lit but when I touch the alligator clip to the touch plate the digitize green light comes ON
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The G31 Z-3 F20 is a probing move, causing the tool to go down a MAXIMUM of 3", but it should stop when the probe is triggered. Only if the probe input is not triggered will it move the full 3". It sounds like your probe (digitize) input isn't being registered. You can make a probing move from the MDI without writing a macro, just type in
G31 Z-3 F20 and check that grounding the touch plate stops it.
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It didn’t work John, had to use the E-Stop again
How do I find out if the probe is registered?
If the diagnostic screen shows the green light on the digitize and touching the plate on/off the light also turns on/off isn’t this an indication the probe is working?
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It happens so fast, I remember the second try I touch the plate twice with the alligator clip, the first didn’t work but the second time it did go up.
Should I use 120ohms resistor?
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Apologies John, one of my probe connections was loose and after tighten it now the probe stops but it doesn’t go up, just stops. I did it a few tries using the script/midi with the same result.
The last line on the script says G1 Z1, perhaps it should be –Z1?
I hope I don’t do anything else stupid
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Hi,
a block like:
g31 z-1 f20
will cause the machine to travel at 20 in/min to z = -1 inch or when the probe activates, which ever comes first. It does not turn around and drive upwards again.
It will, but you have to tell it explicitly what to do, for example:
g31 z-1 f20
g0 z1
The g0 z1 will cause the machine to drive to z =1 inch, presumably above the material, but only after Mach has latched the probe values into the pound registers.
Craig
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Thanks Craig, but the last line on my script is “G1 Z1” and tomorrow I will change it to “G0 Z1”.
Reading the User’s Guide again (see picture) I noticed pin 15 where the probe is connected already has a resistor and I have set the jumper to pull-up. Tomorrow I will remove the 1K resistor I installed and hopefully all will be fine.
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try writing "Code" rather than "code" in the last line.
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Starting work late this morning and I hope to finish this subject today
I will do the change as you suggest John, thanks
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Unexpected visits delayed my todays work…..
Finally the probe works and I don’t know if changing the “code” to “Code” had anything to do with it. I attach 3 pictures to see the layout. I’m not setup yet to take a video of the probe working but I will be pretty soon.
It’s possible the problem was related to my motors because I discover there may be a problem with the motors despite that they all jog properly and I will start a new thread about this subject.
Your help is much appreciated
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"Code" is a defined command in the visual basic assembler, "code" is just a word.