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KMD Renner Key Measuring Device Comparison to tradional method

  • 1.  KMD Renner Key Measuring Device Comparison to tradional method

    Registered Piano Technician
    Posted 18 days ago

    I'm starting to take measurements with Renner's new KMD - Key Measuring Device.  I'm finding that the results are generally higher by 3 or 4 grams than those taken with the traditional  Down Weight by finding the weight that causes the hammer to rise in a controlled motion after a few light raps to get it started and mirroring that motion with Up Weight.  I expect the consistency with the KMD will be much less subjective and way more consistent than the traditional method and it's way faster.   Any one else have input on this?



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    David Stanwood
    stanwoodpiano.com
    stanwood@tiac.net
    508-693-1583
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  • 2.  RE: KMD Renner Key Measuring Device Comparison to tradional method

    Registered Piano Technician
    Posted 18 days ago

    David

    The KMD is taking dozens of readings all the way down and up through the key dip. However, the touchweight analysis range is only between 2 and 4 millimeters. That might be the source of the discrepancy you are observing. I have found it to be more accurate than manually setting weights on the keys because of the consistency of force, the multiple measurements and the consistent analysis range.  I wouldn't hesitant to talk to Skylar the engineer that invented the device if you have questions.  A very nice young man.  Chip has the email address.  I don't have it right in front of me.

    --Dave



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    David Severance RPT
    Clarkston WA
    (208) 798-9703
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  • 3.  RE: KMD Renner Key Measuring Device Comparison to tradional method

    Registered Piano Technician
    Posted 17 days ago

    Curious what % the battery charge is when you're taking these measurements.  



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    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
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  • 4.  RE: KMD Renner Key Measuring Device Comparison to tradional method

    Registered Piano Technician
    Posted 17 days ago

    FWIW, after reading your post I went to an action that I just done and the measurements were all over the place and inconsistent from one to the next and under what I thought they had been by anywhere from 3-7 grams.  I noticed that the battery was at about 60% so I recharged and remeasured this morning and it measured both consistently and accurately when compared with using gram weights.  I don't know if that was a one time anomaly or what but I will allow the battery to run down some and try again.  Should probably be looked into though.  



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    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
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  • 5.  RE: KMD Renner Key Measuring Device Comparison to tradional method

    Registered Piano Technician
    Posted 16 days ago

    Very Interesting DL. The instructions do say that when the KMD is calling data into the app through Bluetooth that it is a battery hog. Maybe we should keep it plugged in when measuring. I've been talking to Skylar about summer of the discrepancies I've been finding, but I am optimistic about having a device that will clear up some of the measuring discrepancies we already experience. I propose we standardize measuring to the outside edge of the key for more consistency with the distance ratio. The 13 mm the Dom Galt suggested as where pianists play is obsolete. Robert Springer recently suggested to me that we define the distance from the fulcrum and express a true torque measurement in newtons. I agree with him. I think we'll find different specs for concert grands than small baby grands.



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    Jude Reveley, RPT
    President
    Absolute Piano Restoration, Inc.
    Lowell, Massachusetts
    978-323-4545
    www.absolute-piano.com
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