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Key button replacement

  • 1.  Key button replacement

    Registered Piano Technician
    Posted 03-25-2019 14:38
    Anyone have a good and detailed article, including jigs, for replacing an entire set of key buttons?

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    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
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  • 2.  RE: Key button replacement

    Posted 03-25-2019 19:15
      |   view attached
    Nope on an article. Here's what I do, if that would be helpful...

    -Rebush fronts (if that is part of the job)
    -leave old buttons on the keys for now.
    -install keys on keyframe, space etc, until they are where you want them at the end of the button installation
    -prepare 2 keyboard wide pieces of poplar or something like that about .5" x 1.5" x 52 or whatever. 
    -place the poplar on the key backs .   Drill through the poplar stick at 1 and 88 into the key and insert the index pins through the poplar and into the key. also drill index pins into the keyframe. This indexes the poplar repeatably, side-to-side, and front to back on the keys
    -​mark center of each key on the stick (this is not too picky)
    -remove the poplar stick and drill .086 holes at the marks on the poplar on the drill press for vertical accuracy. 
    -place poplar back on the keyset, indexing the poplar carefull to the previous index points. drill through each of those holes you just drilled, into each key.
    -insert 7 bridge pins in all the keys
    -you have now basically reconnected the keys into their pre-cut-apart condition. This is the concept of the whole procedure...reconnect the keys into their pre-cut-apart condition.
    -Now you can remove the keys, remove buttons, and when the keys are put back on the frame, with the poplar sticks and bridge pins, the keys will be in their proper spaced orientation, even when there is no button.

    For the actual button installation:

    -install onlyevery other key on the keyframe.  install the poplar and bridge pins
    -lay a straight edge along the keys where you want the front edge of the button to be. This will guide the placement of the new buttons
    -hold one button at a time on to of each key, rough mark bandsaw cut lines, cut the buttons roughly to general shape on bandsaw, indexing the front of the button to the straight edge
    -glue the rough cut buttons using rub fit PVA. No clamping as it just moves things around. A rub fit works fine..or use hot hide and a rub fit.
    -remove these keys, glue the rest of the keys, and rout the buttons flush to the key sides.

    If your straigtedge is carefully placed and not allowed to move, as you rub the glue surfaces together, the front edge of the button will be the index 90 deg off of the straight edge, to align the button mortise orientation. 

    I've done this numerous times...works fine. 

      
      



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    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
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  • 3.  RE: Key button replacement

    Registered Piano Technician
    Posted 03-25-2019 22:09
    Thanks Jim, 
    That is a beautiful plan. I never thought of making indexing sticks. Thank you sir!

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    Edward McMorrow
    Edmonds WA
    425-299-3431
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  • 4.  RE: Key button replacement

    Registered Piano Technician
    Posted 03-26-2019 08:37
    Yes indeed!   👍👍

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
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  • 5.  RE: Key button replacement

    Registered Piano Technician
    Posted 03-26-2019 08:42
    Hi David,
    John Hartman had two articles in the March and April 2001 PTJ. I've used this system before, and it worked well for me.

    All the best,
    Jon






  • 6.  RE: Key button replacement

    Registered Piano Technician
    Posted 03-26-2019 09:10
    Thanks Jim and I'll check out the Hartman article too.

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    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
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  • 7.  RE: Key button replacement

    Posted 03-26-2019 23:14
    Since a picture is worth a thousand words, here are some videos that might give you a few ideas. I hope they download ok.  If they do I have some more pics and I'll write a short explanation.

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    Glen Hart
    Grand Junction CO
    970-434-5558
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  • 8.  RE: Key button replacement

    Posted 03-27-2019 10:26
    How are you sighting the key relative to the laser index?  interesting.

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    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
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  • 9.  RE: Key button replacement

    Registered Piano Technician
    Posted 03-27-2019 11:11
    Sweet!  You've given me some ideas.  But please post more pics if it's not too much trouble.

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    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
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  • 10.  RE: Key button replacement

    Posted 03-29-2019 23:29

    I'm afraid I can't take much credit for this design. Years ago I bought  a Jaras key button jig.  I was not happy with how it worked so I took it apart and kept the part you see and combined it with my regulating bench and the rest is history.  In answer to some of your questions.  The key pin of the jig rotates forward and backward,  moves up and down and is interchangeable  to match the pin in the piano.  The rails of the bench are set parallel to each other.  I position the jig height on the rail so the key, when clamped, is close to being  at mid-stroke. The key is positioned on the front rail with a square and clamped. If the keys are twisted you'll see the key lean to the side at the balance rail pin.  You can put a taper gage under the front to support a bad key or to indicate how much to plane off the bottom of the key.  There are some creative things one can do with a hand plane to the key shoe, the underside of the key, along with the placement of the button  to get a warped key to sit and travel straight.  This will also either fix or create problems with the capstan and backcheck.  Of course it's best to properly fix a twisted key before you start the job. I'm not sure this would be evident if you installed buttons while on the keyframe until one side of the bushing wore out. (bad syntax but it's 2am and I don't care!)

    After the key is squared and clamped to the front rail, the button is placed on the key and the small "fork" of the jig is placed into the mortise and moved laterally to be directly over the key pin which positions the button into its proper fore-aft and side to side position.  

    PLEASE use hide glue. You saw in the video how easy a hide glue joint can come apart with the right leverage and blow.  I know pva will work fine and that it will soften with heat but there is always some damage somewhere at removal and the next glue joint is questionable unless care is used to get to clean wood below the original surface.  Almost every key button job I've done is because the bushing mortise has been damaged because of the glue.  I always charge more when I have to deal with non-hide glue.

    BTW, I have a shaper (like the J. Hartman article), a router, a bandsaw and a Bridgeport mill, and have used them all to remove buttons.  None of them come close to a hand plane.  If you don't have an absolute love affair with your plane then you either have a bad plane or it's not sharp or both.

    I used this system for some 20 years before I bought a used laser at a thrift store. It adds a little bit to the process but not much.  Mostly it's just cool. When the fork of the jig moves down into the mortise the laser is directly on top of it and it gives a good visual that everything is correct.  The laser doesn't index the key; it indexes the mortise of the button.   Otherwise I just make sure that the fork is directly over the key pin which slides the button into the correct position. With supply house buttons I don't worry about lining up the ends of the wood. I usually make my own buttons. I make them end to end, not side to side. If you make them out of wood that is too hard it will be very difficult to size them with pliers since the pliers don't size the felt but compress the wood.   I like to have the bushing cloth fold underneath the button and to cut the cloth flush on the top of the button, again with a SHARP chisel then plane. In this way the bushing doesn't get pushed out by the balance rail pin.  This is the best way for leather bushings that are expected to last a long time..  I've used this for over three decades and I'm very happy with it.  It is also fast - 5-6 hours max, and that is trimmed and back in the piano. For trimming the sides of the button, nothing beats a block plane.

      



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    Glen Hart
    Grand Junction CO
    970-434-5558
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  • 11.  RE: Key button replacement

    Posted 04-02-2019 12:16
    Just tried Glen's button removing trick, using the sheet metal bending Vise-grip he showed.  With slight warming from a heat gun, popped of pretty cleanly. Very minimal prep for the button.  Original from 1905, hide glue.

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    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
    ------------------------------