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Workbee limit switches LEDs flash red but dont stop machine during test

Discussion in 'CNC Mills/Routers' started by maxhill, Jul 11, 2020.

  1. maxhill

    maxhill New
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    Hi

    I've recently converted y axis belt to screw and re-did the setup , upgrading of software and the axis testing.

    After disabling the "jog restriction before home" line I tested the axis and switches. Then I homed Y axis and the machine went straight through the limit switch Y and I had to hit emergency stop.

    Looks like the limit switches aren't stopping the machine even though the board shows red led when depressed. I can jog the machine while depressing switches, which would explain why homing got the bad result ?

    Am I missing something here? DId the software upgrade do something wrong?
     
    #1 maxhill, Jul 11, 2020
    Last edited: Jul 11, 2020
  2. Alex Chambers

    Alex Chambers Master
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    Is this the Duet controller? Did you remember to change back the M564 line to S1 H1?
    Alex.
    PS the Duet only uses the switches for homing with the Ooznest firmware, it uses soft limits to protect the machine and ignores the switches unless running a homing cycle.
     
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  3. maxhill

    maxhill New
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    Right, so they should only stop the machine when homing. I'm assuming I can leave the line to H0 while homing and it wont ignore the the switch then. At least thats what the documentation says at 4. Testing Your WorkBee

    Not sure what happened with my initial failed test. Maybe the limit switch was too far out.


    Thx
     
  4. Alex Chambers

    Alex Chambers Master
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    I found I had to put the limit switches the opposite way round from the instructions to make sure that the Y gantry plate hit it reliably.
    Alex.
     
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  5. maxhill

    maxhill New
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    Looks like my z limit switch is not wired properly. Just hit the metal with it and got the awful grinding noise. ☹️

    Looks like a bad contact because when I push the connector into the board the led flashes when I depress.

    Will have to have closer look tomorrow.
     
  6. Alex Chambers

    Alex Chambers Master
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    The Z limit switch location is pretty poor - difficult to get at and if you follow Ooznest's instructions the wiring is vulnerable to rubbing against the X drag chain. When you have it working reliably tape or clip the cable to the edge of the X gantry plate. I printed a spacer to move the drag chain out slightly :- Workbee X Drag Chain spacer by HalifaxAlex
    Alex.
     
  7. maxhill

    maxhill New
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    So this was strange. It wasnt the connector. Think it was interference or something. I noticed it wasn’t fiddling with the cable and connector that made the led light up. It was the fan plate that made it light up !

    I could pinch the fan plate and board plate and make it work reliably.

    I unmounted the fan plate and it worked perfectly. After mounting the fan plate again everyone is working fine.

    Interference? Who knows.

    Anyway we move on.
     
  8. Alex Chambers

    Alex Chambers Master
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    In that case, based on personal experience, check the crimp connectors connecting the wiring (all of it) to the headers on the Duet. When I first built mine I (and several others) had no end of problems with the crimps - including some that were broken in the middle and only making intermittent contact. I don't like the type of connectors used - spring pressing against one side of the header pin - I prefer the sort that are a split cylinder that completely surrounds the pin.
    Alex.
     

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