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Homing, Z works, X and Y bang the ends

Discussion in 'Control Software' started by willy44004, Apr 2, 2020.

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  1. willy44004

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    Hello,

    Built a modified Plate Maker a while back and just upgraded to the BB, All limit switches working. Verified multiple times. When Homing is triggered, The Z axis homes like normal, BUT Y and X headbang against the stops.
    Switches are wired normally open, What's driving me nuts is that Only the X and Y headbang. Z works as it should. If I manually trigger a move into the X and Y limit switches it throws a fault. Never had this problem with my X-Pro and the controller is the only change I have made. Here is my grbl configuration.VER:1.1g.20181112
    Grbl 1.1g ['$' for help]



    $0=10 ;Step pulse time, microseconds
    $1=255 ;Step idle delay, milliseconds
    $2=0 ;Step pulse invert, mask
    $3=5 ;Step direction invert, mask
    $4=1 ;Invert step enable pin, boolean
    $5=0 ;Invert limit pins, boolean
    $6=0 ;Invert probe pin, boolean
    $10=19 ;Status report options, mask
    $11=0.010 ;Junction deviation, millimeters
    $12=0.002 ;Arc tolerance, millimeters
    $13=0 ;Report in inches, boolean
    $20=0 ;Soft limits enable, boolean
    $21=1 ;Hard limits enable, boolean
    $22=1 ;Homing cycle enable, boolean
    $23=2 ;Homing direction invert, mask
    $24=25.000 ;Homing locate feed rate, mm/min
    $25=1000.000 ;Homing search seek rate, mm/min
    $26=250 ;Homing switch debounce delay, milliseconds
    $27=2.003 ;Homing switch pull-off distance, millimeters
    $30=32000 ;Maximum spindle speed, RPM
    $31=0 ;Minimum spindle speed, RPM
    $32=0 ;Laser-mode enable, boolean
    $100=197.300 ;X-axis steps per millimeter
    $101=197.300 ;Y-axis steps per millimeter
    $102=200.500 ;Z-axis steps per millimeter
    $110=5000.000 ;X-axis maximum rate, mm/min
    $111=5000.000 ;Y-axis maximum rate, mm/min
    $112=500.000 ;Z-axis maximum rate, mm/min
    $120=50.000 ;X-axis acceleration, mm/sec^2
    $121=10.000 ;Y-axis acceleration, mm/sec^2
    $122=50.000 ;Z-axis acceleration, mm/sec^2
    $130=340.000 ;X-axis maximum travel, millimeters
    $131=325.000 ;Y-axis maximum travel, millimeters
    $132=200.000 ;Z-axis maximum travel, millimeters

    Any help would be appreciated

    Thanks
    Bill
     
  2. Alex Chambers

    Alex Chambers Master
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    Increase $27 to (say) 10 to see if that helps. If it does decrease it until you get to a value that reliably works.
    Alex.

    Also if you set $20=1 (enable soft limits) grbl will stop when you issue a command (or a line of g-code) that would take it past the pull off distance or beyond the machine limits you have set - doesn't cause grbl to shut down and you don't need to restart/regime.
     
    #2 Alex Chambers, Apr 3, 2020
    Last edited: Apr 3, 2020
    Peter Van Der Walt likes this.
  3. willy44004

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    Alex,

    Thank You for your suggestion, Sadly it did not resolve the problem. I pulled the Blackbox controller and re-installed one of my X-Pro's. With the same GRBL settings as posted the problem and the same GRBL firmware, the problem went away. Homing is now working as it should on ALL axis. So it looks like I'll dump the idea of upgrading to a "better" controller and keep one that is tried and true. I also tested the system with a TinyG and it did not exhibit the problem. Just seems to be a problem with the Blackbox. So I'll put the Blackbox on the shelf with my TinyG and Mach4 ( they're for future builds ) and maybe find something I can do with it.

    Just as a side note, All my endstops are in shielded cable and I also have the noise suppression circuitry.

    Again Thanks
    Bill
     
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

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    When you revisit it shout, its probably something simple yet not immediately obvious. A shame its already torn down, pics of the wiring, switches and how you setup your noise suppression would've been welcome to help check it out.

    Min and max switches or min/max only?

    Confirmed using the Troubleshooting tab? Where they green when pressed or red?
    If you had more than one switch per axis, sure you tested the side you are homing against (not just assumed you press the left switch and the troubleshooter sees the signal, that the right hand side one you home to is also working? for example)
     
  5. cmitcham

    cmitcham New
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    does it bang when it first gets there or after pull off? I think $25 is way too high. I forget if it is 24 or 25 that is post-pull off speed.
     
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  6. willy44004

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    It tries to move past the endstop.Broken 2 endstop switch mounts. ( luckily I had ASA printed spares around)

    Switches are wired as per gnea/grbl,( As they always have, originally built the cnc 3 years ago minus the Arduino of course) with
    [​IMG]

    End stops where verified 2 ways, Once in the diagnostics (red) and then triggering moves on each axis, each direction via control/jog axis. Each over travel jog moves triggered a fault consistently when the endstop switch was hit on both direction, on all axis. The really odd part is that the Homing sequence works correctly on the Z axis, only the X and Y axis homing is not sensed. The controller was run with the following firmware installed.

    1) Stock as recieved from Openbuilds
    2) Modified GRBL to enable spindle direction spindle on/off Xloader ( I have a superpid )
    3) Firmware flash via Openbuilds firmware flash Control/Wizard/Flash
    4) Hex build file freshly downloaded from GRBL Website , Xloader
    5) Hex build that I used in my Xpro, Xloader

    Thanks for the Assistance.
    Bill
     
  7. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Not 100% clear from that description: Were they red in default state?
    Should be GREEN when not triggered, Red only when switch is pressed.
     
    #7 Peter Van Der Walt, Apr 3, 2020
    Last edited: Apr 3, 2020
  8. willy44004

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    Open Control/Diagnostics, All Axis's clear of end stops
    All switch indicators are green
    I press one at a time BOTH limit switches on each axis
    Each corresponding Axis Limit Switch Status display Goes RED on press, Returns to GREEN when released.
    X,Y,Z limit switches Are sensed, Their state is sensed,

    The problem IS not the limit switches. That has been not only been proven by the Control Diagnostics, I have also verified it with A multi meter ( ohms test and continuity test, 0 ohms when pressed, infinity when released, Beep when pressed, silent when released). It has also been proven via MY X-Pro controller Running the same firmware as the BB. Homing function with it operates as expected repeatably.

    I retired from being an Industrial Controls Engineer after 30 years. Built my first CNC 5 years ago, First 3d Printer 2 years ago, and just completed a Laser setup. I always apply the KISS ( keep it simple xxx) principle when I encounter a problem.

    Again
    Thanks for your assistance.
     
  9. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Thanks for the update, sounds good yes.

    Is your xPro set to 1/8th microstepping (like the BlackBox) if not, adapt your values to 1/8th microstepping (if your xpro was on 1/32nd for example, your steps per mm is out by 4x too much, and thus moves go 4x faster and 4x further)


    Grbl default is 500mm/min
    If your microstepping is different, you may well be homing at 2000mm/min (if Xpro is 1/16th) or 4000mm/min (if xPro is 1/32nd)

    Z is limited slower than XY... another clue that its hitting XY too fast?

    Multimeter is the less interesting one: We want to be sure GRBL sees the signal change (whether wired correctly or not) - the fact that Troubleshooting DOES show it detecting correctly means the BlackBox hardware is 100% and means we need to look at Grbl settings...

    BlackBox has onboard Noise filtering (RC filter on all endstop and probe inputs) : Connect your switches as shown in docs.openbuilds.com (without extra circuitry) - two sets of RC filtering may be too slow a rise time...
     
    #9 Peter Van Der Walt, Apr 3, 2020
    Last edited: Apr 3, 2020
  10. willy44004

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    Xpro configured for 1/8, I'll remove the filtering and drop the homing speed. I'll try that as soon as I swap the BB back in and let you know whats happening.
     
  11. willy44004

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    OK, re-installed the controller, removed the de-bounce first and re-tried home. It still head banged. Changed $25 to 250, homing worked, bumped it up to 500, it worked. I arrived at the $25=1000 by testing what the max was with the Xpro. Maybe the internal de-bounce circuitry is too conservative. I was running the CNC almost 24 hours a day for the first year I built it, so the slow homing time added up. I was milling parts that too 1 1/2 hours so I was homing a lot.

    Now all I have to resolve is getting the super-pid to shut off completely.

    Thanks for You Assistance
     
    Giarc and Alex Chambers like this.
  12. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Definately errs on the side of Reliable / Newbie friendly (;


    SuperPID: Check $31 setting in grbl settings
     
  13. willy44004

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    Peter,

    Thanks for the response. Resolved the problem over the weekend. Compiled a modified GRBL removed the comments from the following lines.

    #define USE_SPINDLE_DIR_AS_ENABLE_PIN
    #define SPINDLE_ENABLE_OFF_WITH_ZERO_SPEED
    #define INVERT_SPINDLE_ENABLE_PIN

    Works perfectly. Now on to tweaking the calibration, leveling the platen and trammeling the router head. Due to the stay in place, I finally have time to do all the tweaks, and add-ons that have been in planning.

    Hope every one on the Forum is Safe and Well

    Bill
     
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