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  1. #1
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    Sep 2006
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    39

    zero offset margin too small

    Every morning I am getting this error message. I wiped the sensor off with a rag, any ideas what caused it. What is the "grid offset"?

    166 Y ZERO RET MARGIN TOO SMALL - This alarm will occur if the home/limit switches move or are misadjusted.
    It indicates that the zero return position may not be consistent from one zero return to the next. The
    encoder Z channel signal must occur between 1/8 and 7/8 revolution of where the home switch releases. This
    will not turn the servos off, but will stop the zero return operation. Check grid offset.

  2. #2
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    Dec 2007
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    17
    I will explain this as best I can. When the machine is "zeroed", the axes travel to home switches and then back away from the switches to a specified offset. This grid offset becomes the zero point when the machine is in use. This alarm you are getting indicates that the margin is too close to the switch.
    You can also look for chips on the trip flag. Chips can sometimes cause the switch to trip too early. You didn't mention any other problems with the machine, such as excessive backlash, but this can also cause a grid margin alarm in extreme cases.
    Sometimes, no problems can be found and then axis simply needs a grid offset adjustment.
    In Zero Return mode, the distance to go that is displayed on the screen is the amount that the motor rotated away from the switch to the grid offset. The alarm will occur if the distance to go becomes less than .0295 or greater than .2065. The ideal amount is .118.

    Here is the procedure for setting the grid offset:

    1. Set the grid offset to zero. (Parameter 125,126, 127, 128, or 170, (depending on the axis being set.) Always write down the original value.

    Setting #7 (Parameter Lock) must be OFF and Emergency Stop button pressed in before any parameters can be changed.

    2. Press Zero Ret, then the axis you are setting (X, Y, Z, A, or B), and then press Zero Singl Axis.

    3. Calculate grid offset using the following formula, and write the result in Parameter 125 (X-axis),126 (Y-axis), 127 (Z-axis), 128 (A-axis), or 170 (B-axis).

    (Distance to Go - .118) x Ratio = Grid Offset.

    The Ratio (steps/unit) for the X, Y, Z, A, and B axes are the values in Parameters 5, 19, 33, 47, and 155, respectively.

    When finshed, cycle the power on the machine and test it.

  3. #3
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    Sep 2006
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    Wow, thanks!!

  4. #4
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    Sep 2015
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    Re: zero offset margin too small

    Thanks for that explanation HemiRoadRunner, you got me up and running!

  5. #5
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    Feb 2012
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    Re: zero offset margin too small

    HemiRoadRunner, you are a lifesaver! THANKS!

  6. #6
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    Nov 2016
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    3

    Re: zero offset margin too small

    Another thank you to HemiRoadRunner for steering us in the right direction.

    I found this forum post via a Google search for Alarm 165 "Axis Zero Return Margin is Too Small", specifically for an HRT160-P3 4th-Axis (A-axis) rotary that I recently connected.

    As many Haas operators using the new NGC control are aware of, none of the parameters listed in this post are accessible to the operator, or even the service technicians. However, Haas has implemented a feature to set the grid offset automatically (for rotary axes, anyway, that I am aware of). Under the Settings page, scroll over to Rotary, and move down to the selected Axis that needs the Grid Offset adjusted. (I had to press EDIT or I kept getting a status message "Wrong Mode".) Once the axis was selected, on the right side of the upper right window, a "Set Grid Offset [ALTER]" option is present. I verified, with a call to my local HFO, that this is the correct method to set the grid offset for a rotary, and it worked, I pressed ALTER, the rotary moved a few degrees in both directions, and that was it - no more 165 Alarm. I'll try to upload a screenshot of the Rotary screen on the control. Whether this information is useful for any of the original 3 XYZ linear axes of a mill or the X,Z axes of a lathe, I don't know.


  7. #7

    Join Date
    May 2020
    Posts
    1

    Re: zero offset margin too small

    HemiRoadRunner, this solved my problem with minimal hassle.

    I bought an old/used VF2 (1996) and this was one of the last and least of my problems to fix. Thanks to you, I checked this one off my list quickly. I'm saving this thread in case I need it again in the future.

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