Author Topic: Odd Homing Behavior  (Read 958 times)

ggallant571

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Odd Homing Behavior
« on: August 12, 2020, 07:38:24 PM »
I have a core-xy etcher that has been in use for over two years. Recently started having odd behavior when performing homing operations. About 50% of the time it works as expected. Triggers the limit switch on the Y rail, backs off a bit, drives the carriage along the X rail till the limit switch trips, and backs off 5 mm. The other 50% it does a small surge and stops wait an "error<-1>" message on the console.

Firmware is grbl-1.1f.

Can replicate in a terminal emulator by typing $h.


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Zax

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Re: Odd Homing Behavior
« Reply #1 on: August 13, 2020, 04:29:00 AM »
Does it locate the switch and then jump back?

Increase the debounce $26 or slow down the search speed, it's probably the switches getting cranky - it happens with old age ;)

ggallant571

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Re: Odd Homing Behavior
« Reply #2 on: August 13, 2020, 06:13:28 AM »
I got cranky decades ago. The laser head can be well away from the switches (100 mm) and the motion is not towards the switches. Actual error message:

Error : <-4>error:8

The initial motion serge is probably my host code. I move the head 5 mm in both X & Y when doing a homing operation. Can remove and retest.

This is the gcode:
    G91
    G00 X 5 Y 5
    G90
    $h
    G92 X 0 Y 0 Z 0



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ggallant571

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Re: Odd Homing Behavior
« Reply #3 on: August 13, 2020, 06:18:49 AM »
Just looked up what error code 8 means.

   "Grbl '$' command cannot be used unless Grbl is IDLE. Ensures smooth operation during a job."

Looks like I need to wait for motion to complete before issuing the $h.

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