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End stop placement and z axis min or max

Discussion in 'CNC Mills/Routers' started by James marr, Dec 31, 2019.

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  1. James marr

    James marr New
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    i have a 1500x1500 work bee (Chinese knockoff). The 2 y axis motors are in the rear of machine. Marlin -Arduino 2560-ramps 1.4 pronterface testing

    I want to have it home to the left front corner- (facing the machine)
    Currently I have the y axis MIN endstop placed at the left corner - outside rail.

    The X axis MIN Endstop is located on right side of machine (opposite of motor) on rear rail of gantry.

    The Z axis question is - if the Endstop is placed on the bottom of rail is that MIN OR MAX? Also on the Z jog is up - raising the rail up or does it mean moving the tool closer to the bed?

    I am at a point where all motors are functioning. And I can jog left right up down front and back. I have not homed yet because I am not sure where z 0 x0 y0 are or where they will go when I press home.

    Thank you in advance.
     
    #1 James marr, Dec 31, 2019
  2. James marr

    James marr New
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    What no takers- I bought half my parts at openbuild?
     
    #2 James marr, Dec 31, 2019
  3. Christian James

    Christian James Journeyman
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    You said you have a Chinese knockoff 1515 - what did you need to buy from OB?
     
    #3 Christian James, Jan 1, 2020
  4. Rob Taylor

    Rob Taylor Master
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    Is it intended as a large format printer? Just confused as to why it seems to be running printer firmware. grbl would be the more standard option for a gantry router, and easier to calibrate for all these directional and positional options.

    Reading the grbl wiki would likely answer all of these questions, too.

    z homes positively- ie. upwards. There's no set depth to which you can feasibly repeatably home it and actually make use of, especially if you already have a part on the table or a tool in the spindle. You then touch off (your part, the table, whatever) to get your G54 z offset to work with.

    I suspect no one's answering because had you searched "homing direction" in the search box, the very first result is this likely-useful thread: Homing Question

    People- particularly in technical hobbies like this- generally aren't too big on helping people who don't appear to have even attempted to solve the problem on their own yet, but if you show your work, they'll bend over backwards to help, for weeks on end, sometimes.
     
    #4 Rob Taylor, Jan 1, 2020
  5. David the swarfer

    David the swarfer OpenBuilds Team
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    This is incorrect. X+ is tool moving right so that would be the MAX endstop (and the correct home)
    Z limit is ALWAYS at the top, which is Z+. this is for your and the machines safety and is the industry standard.
    industry also wants the X and Y home as the positive ends but since this is not nearly as much of a safety issue you can move them if you want to, but not Z, Z must home up and away from the work.
    Z always homes first so moving up it will clear the stuff on the table so that the X and Y homing is safe motion.
    all axis directions are meant as tool motion
    so X+ is tool moving right
    Y+ is tool moving away
    Z+ is tool moving up
    This cannot be changed because every Gcode generator assumes these directions.

    I must encourage you to do 2 things:
    1 - stop thinking about where machine 0,0,0 is (and in particular worrying about the workspace being negative, it does not matter). The standard is the positive ends of travel. Leave it there. It makes all the setup much easier. It also just does not matter since to use the machine you will jog the tool to the workpiece starting point (which is defined in the CAM, usually bottom left corner for X and Y and top of the material for Z). Then you set Work Coordinate zeros there. At no time in this process have you actually looked at the machine coordinates (-:

    2 - disable hard limits, and disable homing until after you have everything else working correctly. Get axis directions correct, and get axis calibration correct first. And cut a test piece in insulation foam too. After this is all working you can read up on how homing is setup and set it up correctly the first time.

    one more thing... I think you will quickly become disillusioned with Marlin and the Ramps board. They are designed for 3D printers and do not do routing very well at all. In particular the drivers do not supply enough current to make the Workbee happy. So maybe you should plan now on moving to a Blackbox or similar sooner rather than later.
     
    #5 David the swarfer, Jan 1, 2020
    Peter Van Der Walt and Alex Chambers like this.
  6. James marr

    James marr New
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    Shielded cable endstops connectors various hardware screws corner bracing etc
    The unit I purchased was just the gantry
     
    #6 James marr, Jan 1, 2020
  7. James marr

    James marr New
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    Thank you - I started this project in June 2019 - I basically had to trouble shoot myself.
    The motors would not turn.
    Solution:
    Purchased smaller motors 1.7 nema
    Computer boards endstops stepper drivers
    Then tested system
    Then removed each component: stepper motor tested.
    Stepper driver tested
    Boards tested
    Everything was operational
    Rechecked wiring - found problem - pulse and directional were switched.
    Fixed problem
    1axis at a time
    Found 3 more wire connector issues- wired directly to stepper driver to motor for x axis. Fixed problem
    Z axis connector -intermittent connection fixed problem
    Ground wires on stepper driver - crimp connectors (bad or loose connections) soldered all connections ( strongly recommended.
    Recently purchased m16 military style connectors from case to cables . Replacing today.
    I have watched over a hundred hours of you tube and websites. To get to this point of the project. My initial website that provided inspiration- fell off the end of earth and provided zero help.

    I am at the last portion of being fully operational.
     
    #7 James marr, Jan 1, 2020
  8. James marr

    James marr New
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    Yes - that is solid advice that I will follow. Thank you so much for clarification.
    The Arduino and ramps 1.4 have 4.5 amp external drivers to power nema 23 stepper motors.
     
    #8 James marr, Jan 1, 2020

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