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Bedding the keyframe

  • 1.  Bedding the keyframe

    Registered Piano Technician
    Posted 03-19-2017 13:49

    When I first became a piano technician the Journal articles written by Bill Spurlock were very helpful  For those of you who remember them, they were beautifully written, concise and clear.  Sometimes I go back and read them and always find things that I have forgotten. 

     

    I was recently re-reading his article on bedding the keyframe.  Bill makes the following statement, "turning the glide bolts completely out of contact with the keybed may significantly change the key height.  You would have then created needless work of resetting the key height and dip from scratch."

     

    Normally when I bed the keyframe I turn all of the glide bolts up so none of them are making contact, then I turn them down one by one until they are all making slight contact, always going back to recheck the ones I already did.  I believe this is a fairly standard procedure.  I have not had the experience of completely altering key height and key dip.

     

    I am wondering why Bill issued that warning.  Is it really possible that taking the glide bolts very slightly out of contact for only a few minutes could drastically change the key height and key dip?  Are others using the same procedure I use?

     

    Note that Bill's article is not about the more complete method of  keyframe bedding where you remove the top stack.  His method is for use in the field with a piano in reasonably good condition.

     

    Thanks,

     

    David

     

    David Weiss

    Registered Piano Technician

    (434) 823-9733

    davidweisspiano@gmail.com

    www.davidweisspiano.com

     

     

     

     



  • 2.  RE: Bedding the keyframe

    Posted 03-19-2017 14:50
    David-
    Key frames vary in their flexibility, so, relative to the given piano, there may be a small range of acceptable adjustment of the glide bolts, which should not lift the frame into a stressed position in the front or back. It doesn't take much change in the balance rail height to make a detectable change in the key height.
    Therefore, in a field regulation or touch up, a certain amount of leaving well enough alone applies. The method Bill gives, checking for contact by pressing with a small block of wood, does a great job of making the best of the given overall adjustment without changing the given height of the rail.

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



  • 3.  RE: Bedding the keyframe

    Posted 03-20-2017 09:21

    The WNG Key  Bedding Gauge is the easiest way to achieve what you are looking for.

    Chris Solliday RPT



    ------Original Message------

    When I first became a piano technician the Journal articles written by Bill Spurlock were very helpful  For those of you who remember them, they were beautifully written, concise and clear.  Sometimes I go back and read them and always find things that I have forgotten. 

     

    I was recently re-reading his article on bedding the keyframe.  Bill makes the following statement, "turning the glide bolts completely out of contact with the keybed may significantly change the key height.  You would have then created needless work of resetting the key height and dip from scratch."

     

    Normally when I bed the keyframe I turn all of the glide bolts up so none of them are making contact, then I turn them down one by one until they are all making slight contact, always going back to recheck the ones I already did.  I believe this is a fairly standard procedure.  I have not had the experience of completely altering key height and key dip.

     

    I am wondering why Bill issued that warning.  Is it really possible that taking the glide bolts very slightly out of contact for only a few minutes could drastically change the key height and key dip?  Are others using the same procedure I use?

     

    Note that Bill's article is not about the more complete method of  keyframe bedding where you remove the top stack.  His method is for use in the field with a piano in reasonably good condition.

     

    Thanks,

     

    David

     

    David Weiss

    Registered Piano Technician

    (434) 823-9733

    davidweisspiano@gmail.com

    www.davidweisspiano.com

     

     

     

     



  • 4.  RE: Bedding the keyframe

    Registered Piano Technician
    Posted 03-20-2017 16:46
    Agreed, Chris. Very precise feedback concerning when contact with the keybed is made and how much beyond that point one has turned the glide bolt. More than one WNG Bedding Gauge is even better. (And no, I don't get a commission for saying that!)

    Alan

    ------------------------------
    Alan Eder, RPT
    Herb Alpert School of Music
    California Institute of the Arts
    Valencia, CA
    661.904.6483
    ------------------------------

    Original Message


  • 5.  RE: Bedding the keyframe

    Registered Piano Technician
    Posted 03-20-2017 11:46
    The message I get from Bill's warning is that the keys might have been leveled and dipped with the glide bolts screwed down so far that they lift the balance rail significantly. If that is the case, raising the glide bolts will decrease the key ht. and dip.

    Bob Anderson

    ------Original Message------

    When I first became a piano technician the Journal articles written by Bill Spurlock were very helpful  For those of you who remember them, they were beautifully written, concise and clear.  Sometimes I go back and read them and always find things that I have forgotten. 

     

    I was recently re-reading his article on bedding the keyframe.  Bill makes the following statement, "turning the glide bolts completely out of contact with the keybed may significantly change the key height.  You would have then created needless work of resetting the key height and dip from scratch."

     

    Normally when I bed the keyframe I turn all of the glide bolts up so none of them are making contact, then I turn them down one by one until they are all making slight contact, always going back to recheck the ones I already did.  I believe this is a fairly standard procedure.  I have not had the experience of completely altering key height and key dip.

     

    I am wondering why Bill issued that warning.  Is it really possible that taking the glide bolts very slightly out of contact for only a few minutes could drastically change the key height and key dip?  Are others using the same procedure I use?

     

    Note that Bill's article is not about the more complete method of  keyframe bedding where you remove the top stack.  His method is for use in the field with a piano in reasonably good condition.

     

    Thanks,

     

    David

     

    David Weiss

    Registered Piano Technician

    (434) 823-9733

    davidweisspiano@gmail.com

    www.davidweisspiano.com

     

     

     

     



  • 6.  RE: Bedding the keyframe

    Member
    Posted 03-20-2017 13:10
    Just to add to the confusion what about the other methods sometimes used such as tapping down and checking for knock or the newspaper under the glide bolt technique ? I also wonder how you make glide bolt adjustments when the bolts come up from below the key frame and meet either the middle or the front rail. Maybe it would be a good idea to have at it in a future journal article (s).

    I have the WNG gauge that Chris mentions because I found it hard to get my hands into the action and do the pressing down technique with tapping. I have used the newspaper technique as I was taught but have read that it may not be the best. The last time I did some levelling it was on a Yamaha C7 . I had to jerry rig a tool that I "created" using a small box wrench .

    ------------------------------
    James Kelly
    Pawleys Island SC
    843-325-4357
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  • 7.  RE: Bedding the keyframe

    Registered Piano Technician
    Posted 03-20-2017 13:28
    I don't know about other brands but Yamaha deliberately sets their glide bolts to stick out about 1mm. If you turn them back in flush and then try to level the keybed the traditional way you will wind up with way less than 10mm key dip and pretty much no aftertouch. Before setting out to level the keybed to what you think may be correct, best check to see what the manufacturer recommends. Personally, if performance is already just about what I want it to be, I approach leveling the keybed as a very slight touch up adjustment of what's already there. If it ain't broke...

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    Geoff Sykes, RPT
    Los Angeles CA
    ------------------------------

    Original Message


  • 8.  RE: Bedding the keyframe

    Registered Piano Technician
    Posted 03-21-2017 04:37
    Bill's method of pushing down on the balance rail will reveal if the glides are not in contact with the keybed, but won't reveal if the glides are too low. I know some people use the lift and knock method for that, but that is a technique hasn't worked for me. It just seems there is not enough space in the action cavity or a good place to grab and lift the action. Maybe someone could elucidate on that technique or recommend a different test to see if the glides are too low.

    Sent from my iPhone

    ------Original Message------

    I don't know about other brands but Yamaha deliberately sets their glide bolts to stick out about 1mm. If you turn them back in flush and then try to level the keybed the traditional way you will wind up with way less than 10mm key dip and pretty much no aftertouch. Before setting out to level the keybed to what you think may be correct, best check to see what the manufacturer recommends. Personally, if performance is already just about what I want it to be, I approach leveling the keybed as a very slight touch up adjustment of what's already there. If it ain't broke...

    ------------------------------
    Geoff Sykes, RPT
    Los Angeles CA
    ------------------------------


  • 9.  RE: Bedding the keyframe

    Registered Piano Technician
    Posted 03-20-2017 22:02
    Yamaha does teach the use of glide bolt adjustment to adapt to aftertouch loss as a result of seasonal RH change. I believe the standard is to have the glides a bit low, so they could be raised if aftertouch increases too much. Hence, on many Yamahas (perhaps most), you will find that raising all the bolts until they are clear of the key bed, and then lowering them until they just contact, will result in a lower key height, and resultant lesser key dip and aftertouch. I think that is the sort of thing Bill was warning against, and it is a reasonable warning.

    If you do get into that problem, it can be remedied fairly easily by re-establishing the lower glide bolt position. Once everything is bedded evenly, simply turn all the bolts down by an even amount (45 degrees, 90 degrees, whatever will do the job), and then even out between the bolts in the normal, knocking way.

    Rather than the WNG tool, I simply use a 6" rule. I prop/lean it against a key in front of each glide bolt in turn. I adjust the pocket clip so it is just above the keytop (giving a gap of about 1 mm), and then turn the bolt in either direction. That tells me whether it is contacting, and whether it is low. Assuming it is contacting and low (meaning the when you back the glide up, the gap reduces), simply continue until the gap stops reducing (you might need to raise the clip on the rule). Turn the bolt a few degrees in each direction to see where the dead on spot is: down raises the key, up does nothing.

    Move through each glide in turn. If you made major changes, go through twice, or even three times. Now do the lift and knock testing. Do it again pressing on all the pedals (that flexes the keybed down a bit). I find this method fast and efficient, and it doesn't add yet one more tool to my kit I lug around. I already have the 6" rule, weighs next to nothing, takes next to no space. Yeah, I know, tool geeks need to have the cool tool, and I have my share of those as well. But I don't carry many of them around with me.

    This does leave out the problem of the hidden glide, when present. That one should probably always be raised enough initially to be out of the picture (not to the extreme, just so it knocks, so you don't have that far to go in re-adjusting it).

    ------------------------------
    Fred Sturm
    University of New Mexico
    fssturm@unm.edu
    http://fredsturm.net
    http://www.artoftuning.com
    "We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
    ------------------------------



  • 10.  RE: Bedding the keyframe

    Registered Piano Technician
    Posted 03-20-2017 22:47
    Fred,

    Nice trick with the 6" rule. I like that. I have the WNG tool and like it, but it stays in the shop. Otherwise I have always done as you described.

    It is amazing how a sensitive pianist can feel even the slightest change here. I recall once after tuning the Steinway L, I just decided to check the studs. I found one (mid treble) just slightly knocking,  no other problems. Fixed it (client did not know I did anything in there and I didn't say anything). He sat down to play and instantly detected improvement in power and response.  He said: "What did you do? It's so much better!"  Of course I told him then.

    That really taught me to check them all the time, which I do.

    Pwg

    ------------------------------
    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
    ------------------------------

    Original Message


  • 11.  RE: Bedding the keyframe

    Posted 03-21-2017 06:52
    The first step in bedding a keyframe is to raise the glide bolts so they don't touch. Then check the front rail for knocking. The back rail is checked with a long screw driver to reach through the strings to the key frame. Once the rails are not knocking, lower the glides, starting in the middle until there's no knocking. Slightly lift on the top action frame and check for knocking at the balance rail. You want to apply a slight upwards pressure and adjust the glide to remove the knock, this will insure a solid seating.

    All too often, someone will crank on the glides to get after touch and not realize they adversely affected the front or back rail bedding. I'm working on a piano that had severe key frame shortcomings. That piano should have never left the factory, let alone make it out of the dealership. A major remanufacturing endeavor corrected the oversight, I'll post photos and such at a later date. 

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    Regards,

    Jon Page