Loud (no really LOUD) 4th axis hum on mini mill 2 when at rest
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  1. #1
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    Default Loud (no really LOUD) 4th axis hum on mini mill 2 when at rest

    Hi,

    The title say it all, I have a 2010 HAAS Mini Mill 2 with the 4th axis installed with a HRT160, a while back it started humming a bit (as does the Y axis now and then) when at rest (ie no movement servos ON) but it as gotten progressively worse to the point ear protections are now needed next to the machine (I mean this thing is LOUD loud ) and you can actually fell the hum in the table if you touch it.

    The hum stops if you jog it (and the air exhaust filter makes the usual "poof" so I assume it is working fine) but a few second after stopping movement the hum will come back (E-STOP stops it of course).
    My guess is this is servo related, some kind of encoder feedback issue perhaps ?

    In the parameters I've noticed that for the X,Y ans Z parameter D Filter X8 is set to 1 but for the A axis both D Filter X4 and D Filter X8 are set to zero, would changing either of these be advisable or is the HRT servo not compatible ?


    I've sent 2 emails to my local French HFO but no news (sometimes he's very responsive other times not so much, this is a not so much time), and since it's 6 hour drive away calling him in is at minimum 1500 Euros so if there was some way for me to tweak some parameters on this now out warranty and otherwise satisfactory machine it be great...



    Anyone have any ideas ? (And no using the HRT 160 as a paper weight does not qualify as an idea)

    PS It's possible this post is a duplicate, I could have sworn I published it yesterday but I can't find it so maybe I was running low on coffee

  2. #2
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    I wonder if an air solenoid could make that kind of noise? I would call the factory, they are very helpfull troubleshooting and are free.
    they will want the serial number.

  3. #3
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    Sounds like potential servo feedback error. Any tuning procedure in the control for the 4th?

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    Agree with BugRobotics that something in servo feedback and loop bad.
    Why it went bad is a wonder. ?????
    Playing with a "D" filter settings is so complicated.
    Be aware that this "hum" tends to tear up or wear things faster so it is serous.
    Dropping the actual D rather than changing the filter will stop this but with trade off if cutting with the 4th moving.
    Mostly I do wonder why. Sticky bearings or excessive gear lash can do this.
    More bad news is that 50 percent or more of field machine techs sent to help do not understand any of this.
    How can I say this? Well that was me and lord knows so wrong it fixes and parameter changes.

    If was working something basic has gone wrong. Band-aid this as needed to keep running.
    The machine may be talking to you the best it can about not being happy with settings or some mechanical things.

    Filters... maybe just try some and see if it works. This is the guess and check method which sometimes works on part size or servo numbers.
    Bob
    (Of no help here, just random points from ,,, I do not know what)

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    I'm just guessing here but experience in closed loop systems say's either your shaft encoder has a problem, but this may be as simple as a loose set screw, or the optical grating has come loose from it's hub.
    If you can tear it down to that level to check, that might give insight into this issue.
    This sounds like it's oscillating back and forth from chattering feedback signal.


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