Pianotech

  • 1.  Down Bearing Gage

    Member
    Posted 15 days ago
    After a few proto-types, here's what I settled on. I got this idea from John Hartman's (I think) gage, (Rocker Arm).
    Using a spreadsheet designed by Alan McCoy; at 80 mm, a half of a degree has an offset of .027". The outer ring markers are set to .027".
    I place the gage on the speaking length (DB 1), then move the body of the gage to the front pin and take a reading (DB 2).

    I place a shim under the twisted portion to bring the bearing into line.

    During this rebuild, washers were placed on the hitch pins to alleviate excessive down bearing. I can micro-adjust this db now.

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    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
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  • 2.  RE: Down Bearing Gage

    Registered Piano Technician
    Posted 15 days ago
    That's cool Jon, thanks for sharing!

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    Benjamin Sanchez, RPT
    Piano Technician / Artisan
    (256) 947-9999
    www.professional-piano-services.com
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  • 3.  RE: Down Bearing Gage

    Posted 14 days ago
    Hi Jon,
    I am always eagerly awaiting to see what you come up with next. But, i think there is an accrued error that's built in to your design.
    Two Reasons:
    First you set the tool on the windings and place the dial onto the  top of the core. This gives you a false "zero" and the error get worse as the windings get larger.
    Second, by the tool blanketing several strings the individual strings inaccuracies get covered over. Iv'e seen big angle changes from neighbors strings as i'm sure you have too.
    Here's my latest and last Lowell type gauge (as i see no way to improve it after 4 modifications). It features a large bubble with 1 degree lines. So easy to read. And i have made several feet for any situation, and the height goes over any capo bar.  Its spring loaded so it hugs the adjustment bolt. The bubble has a slightly slower fluid that makes seeing the smallest angles a joy. And its easy to get one at Home Depot.
    Regards
    -chris


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    Chernobieff Piano Restorations
    "Where Tone is Key, and Mammoths are not extinct."
    865-986-7720 (text only please)
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  • 4.  RE: Down Bearing Gage

    Member
    Posted 13 days ago
    That kind of precision can only be attained with vertical hitch pins, where the down bearing is totally adjustable.
    I'm just striving/hoping to be able to at least get the db in the ballpark.

    I have to start out shy on the low bass because as I advance up the scale the low bass rises as the db is decreased.
    Usually a negative initial reading at the top end of the bridge will come up to zero.

    We strive for perfection but are left with an end product. I'm tweaking the end product to fall into desired parameters.
    It's not rocket science, it's simple mechanical engineering.


    I wonder if the vial in the Milwaukee level can be removed and installed in a Lowell gage. My replacement vial cracked as I was reassembling it in the wrong order.

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    Regards,

    Jon Page
    mailto:jonpage@comcast.net
    http://www.pianocapecod.com
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