Mach3/UC300eth probe 'trigger' issues

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Mach3/UC300eth probe 'trigger' issues

Postby eabrust » Sun Mar 17, 2019 4:25 pm

I've been working on some probing routines in Mach3, and have been having issues with the probe plowing into and through the objects being probed. I noted that despite having an error check to validate probe is not 'pre-triggered' before issuing a G31, if the starting clearance was small (Say between .005" to .0015") the UC300 would not stop when it hit the object, it would just keep plowing ahead.

As a method of trouble shooting, I created a pair of scrips that did the same thing in Mach3 (3.043.062, uc300 plugin v1.015)) and in UCCNC (2106). Essentialy the routine probes the part, retracting a starting clearance value, probes again, then retracting to a smaller and smaller value iteratively until the probing either issued a 'probe active' error or crashed though the part.

In Mach3, the probe would consistently crash 'thorugh' the part if the clearance between part and tip was between .010" or .015" as the G31 is issued. As the feedrate increased, the clearance at which a failure occurred also increased a bit. Going to a very slow feed of 0.5 in/min also still results in a 'crash' This leads me to believe that when the UC300 initiates the G31, it is ignoring the probe signal during the acceleration portion of the move, or during some amount of time. I can also manually position the probe within a small distance, issue a G31 by MDI, and have it plow through the part.

UCCNC behaved perfect and as expected, it would iteratively probe until the tip was in contact with the part, then stop and issue the warning that the probe was triggered. Exactly what I wish Mach3/UC300 was doing.

Based on the behavior, I'm guessing it is possibly in either the firmware for the UC300 (when running for Mach3), or in the plugin driver. This machine used to run via parallel port, and is recently converted to UC300, so I may attempt converting back to parallel and repeat the test to verify it isn't purely a Mach3 hiccup.

I'm attaching for reference the scripts I used for this quick testing in UCCNC and Mach3, if anyone cares to help verify where the problem lies in Mach3/UC300 coordination. (Note: The scripts are written for 'inch' setup, speeds and clearances are all set as variables that should be changed for metric. They are sloppily written, so test carefully :lol: ).

Anyone else had issues like this that they've confirmed? Ideally, I'd like convert all my probing to be done in UCCNC and escape Mach3, but I'm still wishing for being able to G31 probe in combined X/Y/Z moves with UCCNC (pretty please ;) )

Eric Brust
Mach 3 scripts to test in Z and X:
probe test script-Z-Mach3.txt
(1.47 KiB) Downloaded 1 time

probe test script-X-Mach3.txt
(1.45 KiB) Downloaded 1 time

UCCNC scripts to test in Z and X:
(1.38 KiB) Downloaded 2 times

(1.35 KiB) Downloaded 2 times
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Joined: Fri Sep 16, 2016 2:32 am

Re: Mach3/UC300eth probe 'trigger' issues

Postby Fixittt » Sun Mar 17, 2019 7:28 pm

I am working an issue with a UC400 right now and am having a tool length probe issue myself. It seems to be effecting the Uc100 and 400, I have not tried a uc300 yet. My issue is that when I probe the end of a tool I randomly get up to .006 though error on the tool length.

I have found that if I adjust the Max step rate in the UC plug in from 100khz to 50 it seems to solve my probing issue. but this does not help the machines we have that require the higher max step rate due to the high resolution. Maybe this will help you in your problem.
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Joined: Fri Mar 15, 2019 8:54 pm

Re: Mach3/UC300eth probe 'trigger' issues

Postby eabrust » Wed Mar 20, 2019 1:26 am

HI Fixxit,

Good thoughts, but none of that affected what I'm seeing.

With Mach3 / UC300 combo, I played with backlash on/off, buffer size, and step frequency from 25khz to 400 khz, and the result was always that witha gap of ~0.011 inch between probe and part when issuing the G31, the probe plows though the part and ignores the trigger.

I then reverted back to driving the mill via parallel port driver instead of the U300, and running the script results in the desired behavior that running the script in UCCNC does, it probes until the tip winds up touching the part with a gap of <.001" and stops in controlled fashion, so it isn't a 'Mach' problem either. (note: TO clarify the switching between UC300 and Parallel port, the change over is made via DB25 connectors at the breakout boards, so none of the machine wiring is affected, its truly a swap of the UC300 for the parallel port.)

Here is a short vid of repeating the script in Mach3 w/ parallel port driver for reference:

Balzas, have any ideas?

Eric Brust
Posts: 46
Joined: Fri Sep 16, 2016 2:32 am

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