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Thread: Load a part file or run homing operation and get erroneous limit switch warning.

  1. #1
    Join Date
    Jun 2019
    Posts
    8

    Question Load a part file or run homing operation and get erroneous limit switch warning.

    Shopbot Buddy Alpha 48
    I get this window pop-up when I try to load a part file or run a homing macro.

    Use Arrow Keys to move Off of Prox Switch (ESC when Clear)

    My proximity switches glow red, when over the nut the light goes out. Behavior replicated with a screwdriver.

    Limits are set to ON
    Input switch #2 and #3 are set to Nrm Closed Limit

    Before I power up I pull the carriage and table to the hard stops.
    Turn on the control box
    Hit the reset button
    Start the software
    z3 followed by zt
    move .5, .5, 1 and redo z3

    Load a part file and it reads through some number of lines and then I get this:
    Use Arrow Keys to move Off of Prox Switch (ESC when Clear)

    More info:
    The input read-out in the red window shows this
    #1 unlit and green
    #2 lit
    #3 unlit and yellow
    #4 unlit and red

  2. #2
    Join Date
    Jan 2004
    Location
    iBILD Solutions - Southern NJ
    Posts
    7,964

    Default

    You don't need to manually pull the axes on startup. This is more for gantry tools than BT series tools.

    In some cases, if the switch proves to be good (from your test with screwdriver they sound like they are ok) - the controller card can burn out the I/O portion of the controller card - and cause the problems you are running into. Not saying 100% that is the case, but be aware...it happens.

    For now, set the limits to OFF. You can leave the wiring intact if you want or just pull the wires out of the block. To use the tool, just drive it around using SK mode, then position the tool where you want 0,0 to be. Then Z2 (or ZX and ZY by themselves). To Zero the Z, you can use the plate if you verify that Input 1 is working. You only need the input 1 wire and ground. On some tools, you need to put the clip to the spindle (just clip it on anything metal near the Z...one of the nuts holding the Y V-rollers is good enough) and then touch the plate to the bit. See if input 1 lights up on the DRO each time you touch it. If so, you can run the C2 command - which will call up C:\SBParts\Zzero.sbp - hold the plate until it touches twice...don't pull it away after the first touch.

    If the Zzero plate is not working, you can manually set the Z. SK (keypad mode) also has a 'Fixed' mode where you can check it, enter a small value, like .01", and incrementally 'dink' whatever axis that distance each key press. It makes it easier to sneak up on where you need to be ever since SB screwed up the software when the Desktop machines came out...Anywho...Just get the bit where you want it and ZZ. Now Z zero is set. Once the axes are zeroed, there is NO NEED to zero them again until you turn off the control box or lose power, OR change to another tool (Z).

    Anyway - Before you unplug anything or do the Zzero test, be sure to run TS (tools setup) and follow the prompts for the Homing routine and Zzero plate. Be SURE to first, park the tool at physical 0,0 AND be sure to follow the prompts all the way to the end and click on 'I'm Done' - or the settings will not be updated. This could be some of the issue you are having with the limits - so try TS first. If not, try the other things I mentioned.

    Yes - of course it's best to have limits on the machine...but in reality - aside from conveniently locating 0,0 when you enter the C3 command - you don't really need them...nothing is going to fly apart, the motors will time/alarm out if they meet resistance etc...so it's not a deal breaker if you want to play around and do some cutting right now today.
    High Definition 3D Laser Scanning Services - Advanced ShopBot CNC Training and Consultation - Vectric Custom Video Training IBILD.com

  3. #3
    Join Date
    Jun 2019
    Posts
    8

    Default

    Thanks for all of that. It makes sense in relation to my previous experience with a gantry machine running mach3, but it is nice to have it explained specifically with the shopbot lingo.


    Quote Originally Posted by Brady Watson View Post
    Anyway - Before you unplug anything or do the Zzero test, be sure to run TS (tools setup) and follow the prompts for the Homing routine and Zzero plate. Be SURE to first, park the tool at physical 0,0 AND be sure to follow the prompts all the way to the end and click on 'I'm Done' - or the settings will not be updated. This could be some of the issue you are having with the limits - so try TS first. If not, try the other things I mentioned.
    Is the physical 0,0 the same as pulling to the hard stops or is it a floating point .5, .5 off the hard stops? This is the macro that has the "make it easy on me" and it starts a homing routine... This is one of the places I have received the proximity error. By turning limits off would you expect the error to go away? The limits aren't actually triggering when I get the error. Are these problems happening because the TS routine hasn't been completed?

    I can't test any of this until tomorrow. Thanks for the help.

  4. #4
    Join Date
    Jan 2004
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    iBILD Solutions - Southern NJ
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    7,964

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    The physical 0,0 typically being, the corner of the spoilboard. A vbit works nicely as an indicator to reference the center of the bit

    Now that I am thinking about it...make sure the limit for the x axis is in input 2 & y in input 3. If not, it will look for the wrong switch in sequence when homing and will fail.

    Turning limits to off only disables limit functions...it still enables the limits to work during homing.
    High Definition 3D Laser Scanning Services - Advanced ShopBot CNC Training and Consultation - Vectric Custom Video Training IBILD.com

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