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  1. #1
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    Glass Scale ---How to Disable ?

    Working on a 3 Axis Mill and it only has a Glass scale on X axis is there anyway to disable this as i am getting a measuring alarm because of it ?
    Thank you

  2. #2
    Community Moderator Jim Dawson's Avatar
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    Re: Glass Scale ---How to Disable ?

    Does it also have an encoder on the X axis motor? You need some kind of position feedback to the control system. Normally you would find either a rotary or linear encoder on the axis, not both (with the exception of very high end machines with dual loop systems). In other words, without some kind of position feed back you will get an error.
    Jim Dawson
    Sandy, Oregon, USA

  3. #3
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    Re: Glass Scale ---How to Disable ?

    Will Check Jim but Y and Z dont have anything and looks after market to be honest
    The Scale is only on the X and its like a 1 meter travel on this machine
    When its powered up its looking for the X axis measuring which is feed back from it

  4. #4
    Community Moderator Jim Dawson's Avatar
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    Re: Glass Scale ---How to Disable ?

    Does this machine have stepper or servo motors on it? If it has servos, all axis motors have some kind of feedback device. If the glass scale is aftermarket, then it could be that the X encoder failed and was replaced with a glass scale.
    Jim Dawson
    Sandy, Oregon, USA

  5. #5
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    Re: Glass Scale ---How to Disable ?

    Do you have knowledge how to disable it ?
    Or the Parameter Screen to check for install ?
    If it was a Fanuc no issue but not familure with this control

  6. #6
    Community Moderator Jim Dawson's Avatar
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    Re: Glass Scale ---How to Disable ?

    I have no idea what control you are working with, other than you posted in the Heidenhain forum.

    I am going to assume you have servo motors, thus require some position feedback device.

    I am also going to assume that the glass scale replaced the motor encoder.

    Thus, if it is possible to disable the glass scale, the machine is still not going to run because it requires some type of position feedback.

    If the machine is a dual loop system, then it may be possible to disable the glass scale and use the motor encoder only. You would have to look in the parameter screens to see if that could be the case. I suspect that this is not likely.
    Jim Dawson
    Sandy, Oregon, USA

  7. #7
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    Re: Glass Scale ---How to Disable ?

    Yes its a Heidenhain control and cant get to parameter screen on power up unless their is a bypass ?--------Y and Z have a feed back loop for position and use 4 dog point reference switches so i am guessing this was the same --------Usually Glass scale are for high percision which is is in know way that so really dont know why would be there -------I walked into a machine have stripped as emplyoee had left and even the glass scale laying on the bench apart so trying to get it powered up to see were its at with parameters and ladders if i can

  8. #8
    Community Moderator Jim Dawson's Avatar
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    Re: Glass Scale ---How to Disable ?

    I'm not sure what you mean by ''dog point reference switches''. End of travel limits? Switches can not be used for position feedback, only for setting initial position.

    Normally position feedback is by encoders, either linear or rotary. A rotary encoder would either be built into the motor, or would be a separate device attached to the ball screw. Linear encoders (glass scales) would be attached to the table. Either of these would be connected to the controller. If the controller does not see an encoder input from an axis, then it should give an error as this seems to be doing.

    I'm guessing that this machine is equipped with brushed DC motors, most likely SEM brand which can have encoders built into the motors.

    In older machines it is somewhat common to replace a failed rotary encoder with a linear encoder. They do exactly the same job, and connect to the controller exactly the same way.

    The bottom line is that you can not disable an encoder input to the controller and run the machine.
    Jim Dawson
    Sandy, Oregon, USA

  9. #9
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    Re: Glass Scale ---How to Disable ?

    Sorry but i cant get past boot up screen looking for that scale to see more and thats were i need the help
    Linear or Rotary or what type of motor doenst matter it needs feed back encoder from the motor for postion and two axis have that 100 percent so know idea why they put glass scale usually used on a grinder or high percision lathe------------Makes no sense why but just need to get into the system and have a look

  10. #10
    Community Moderator Jim Dawson's Avatar
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    Re: Glass Scale ---How to Disable ?

    Well that's crazy. The controller must be looking for encoders on boot up, which makes no sense to me. That alone should not stop the boot process, but it is what it is.

    What is the model of the controller, let's see if we can find a manual for it. There may be a boot up override procedure.

    Glass (and magnetic) scales are used on many machines, not just high precision ones. I have 3 machines in my shop that are so equipped, none of which I would concider high precision. Interestingly my Super Precision Hardinge CNC lathe does not have linear scales, only rotary encoders.
    Jim Dawson
    Sandy, Oregon, USA

  11. #11
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    Re: Glass Scale ---How to Disable ?

    Company i worked for so many yrs had thousands of CNC nut mostly Fanuc or Siemens and Glass scales we only paid for on 5 Axis machines and on some occasions i had to bypass them to we got new scales ------------Heidenhain we never had any off so new to me ---------Machine powers up and X AXIS MEASURING alarm shows up across the screen ------Will check model of machine and control tomorrow for more info as its a new company i was helping out and got a Doosan and Hass and Bridgeport running for them already

  12. #12
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    Re: Glass Scale ---How to Disable ?

    Machine is Fratelli and Rivolta Italy

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