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Under lever height

  • 1.  Under lever height

    Posted 02-24-2018 10:10
    What is the correct height from Key bed to bottom of underlever on Chinese Baldwin Hamilton Grand ?
          Is this measurement the same for all pianos?

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    Thomas Black
    Decatur AL
    256-350-9315
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  • 2.  RE: Under lever height

    Posted 02-24-2018 11:30
    Hi Thomas:
    There is a jig that Spurlock used to sell that helps set the underlever height. Basically, it is a piece of 1/8" thick aluminum strip that is placed over the ends of the keys. The strip is held up by adjustable "legs" so that it just touches the top of the key ends. The jig is about 10" long. The jig is placed inside the action cavity and put underneath the underlevers so that the strip holds them up. Loosen the damper wires screws so that the dampers rest on the strings. Then tighten the set screws. Done.
    The jig works because of the thickness of the aluminum, which gives an 1/8" clearance between the key ends and the bottom of the underlevers. It will make the dampers rise when the hammers are about 1/3 to 1/2 of the blow distance to the strings. This is what you want.
    Without a jig, you can experiment to see when the keys start to lift the dampers.. Try one note, make it work, then do the rest of them. You can use the damper tray to do this, if you block it up with a wedge, then loosen the screws, seat the dampers on the strings, then tighten again.
    If there is a correct height, I don't know it. Maybe somebody else has that information. But, the above will get you there in case you don't get an answer.
    Good luck.
    Paul McCloud
    San Diego


    Thomas Black
    What is the correct height from Key bed to bottom of underlever on Chinese Baldwin Hamilton Grand ?
    Is this measurement the same for all pianos?

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    Thomas Black
    Decatur AL
    256-350-9315





  • 3.  RE: Under lever height

    Posted 02-24-2018 11:48
    Thanks Paul. I have two jigs that I don’t carry with me every day. I still wanted the measurements.

    Sent from my iPhone




  • 4.  RE: Under lever height

    Posted 02-24-2018 12:31
    Edited by Jon Page 02-25-2018 11:30
    If they are all pretty much lifting evenly-too early, hold a key with the hammer at half blow and measure the height of that damper head above its neighbor. That measurement is the amount to raise the underlevers to set half-blow damper rise.

    If it has spoons, you may have to relocate the top flange on the damper wire for all the underlevers to be at the same height. You can tweak the spoons for individual timing, especially at the low tenor offset.

    My jig is a block of wood with a bolt in it.

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    Regards,

    Jon Page
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  • 5.  RE: Under lever height

    Posted 02-24-2018 13:06
    Tommy

    There is not one measurement for all grands. To figure out what the right height is, measure the top of the key end, at rest. Then measure the height of the key, depressed.

    Dampers should begin to lift when the key travel is half way down. So the height of the damper lever should be half way between the key at rest and the key fully depressed.

    But don't just trust your measurements. After you've set a couple of dampers, side the action in and see when the damper lifts. For some reason, more than once I've done a whole set of dampers, and it was wrong.  (:

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    Willem "Wim" Blees, RPT
    Mililani, HI 96789
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  • 6.  RE: Under lever height

    Posted 02-24-2018 13:24
    Not half key stroke, half blow distance which is abut 3 mm (1/8") key travel.

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    Regards,

    Jon Page
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  • 7.  RE: Under lever height

    Posted 02-24-2018 13:28
    Another method is to measure the height of the key end felt at rest and add 3 mm. Replace action to verify.

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    Regards,

    Jon Page
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  • 8.  RE: Under lever height

    Posted 02-24-2018 16:46
    Thanks Jon and Wim!!

    Sent from my iPhone




  • 9.  RE: Under lever height

    Posted 02-24-2018 19:01
    Thank all of you again for responding. When my best ole buddy RPT told me WNG required 1 1/2” from keybed to underlever, I thought there may be readily available measurements on other pianos I wasn’t aware of. I thought ya’ll may have known something I didn’t know about that particular measurement. I’m still trying to learn and must thank particularly Jon for sharing some new info with me on that subject. Thank all of you.

    Sent from my iPhone




  • 10.  RE: Under lever height

    Posted 02-25-2018 07:34
    Edited by Jon Page 02-25-2018 11:36
    Underlever height would be 1.5" from the key bed if it were a S&S whose key end felt usually is 1 3/8" at rest. That is, if the back rail or key end felt has not been altered unknowingly.  Damper lift is ~1/4", making it ~1 3/4" from the key bed for a S&S (not counting excessive key dip as a result of poor action geometry).

    Now to further complicate the issue. Have you noticed a through dug into the key end felt on some pianos? This is caused by the underlever (u/l) scrubbing on the felt, a consequence of the angle of the u/l being too great. I contend that the key should lift the u/l to parallel to the key bed, thus producing the least amount of friction caused by the forward, sliding motion of the end of the u/l. Lifting beyond parallel reintroduces the sliding motion at the end of the key stroke which will wear the rear corner of the felt. **

    To correct this, measure the height of the key end felt with the front of the key full depressed. Lift the u/l to that height and notice the angle between the u/l and key bed. If the u/l is still sloping towards the front, you have sliding friction. Lift the u/l to parallel and measure. The difference between the two measurements is the amount the tray pivot has to move for the u/l to be parallel. I find generally it's 1/4". The pianist will notice the loss of friction. Photos on request but may already be in the archives.

    If the dampers are lifting early which might be the reason for adjusting, then you might get a two-fer by lowering the tray pivot. You don't need to remove the dampers, just the pivot blocks. If the amount to relocate the pivot hole brings it too close to the original hole; I cut a 1/4" plug from the lower portion of the block. Before you drill everything out, map out the new location for the hole to be drilled once the plug is installed and trimmed. Simply reinstall the blocks. Now, if you're lucky, the damper timing will be delayed to the proper height because the fronts of the u/l's are a bit higher now that you lowered the pivot point; the u/l being suspended by the damper wire at the top flange causes the front to rise as the rear is lowered.

    On one asian make recently, I rose the aluminum rail tray support system 6~8 mm for lifting to parallel, the spoons required minor tweaking. Same theory, reduce sliding motion.

    ** Add to the problem: rough bottom surface of the u/l and the 'sharp' front corner. I sand smooth if the system is removed, eased if not.

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    Regards,

    Jon Page
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  • 11.  RE: Under lever height

    Posted 02-24-2018 17:15
    Jon

    Wouldn't half key stroke create half blow distance?

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    Willem "Wim" Blees, RPT
    Mililani, HI 96789
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  • 12.  RE: Under lever height

    Posted 02-24-2018 17:45
    Wim-
    Keystroke includes letoff and aftertouch.
    Thus, the last part of keystroke does not move the hammer, which has already struck the string.
    One half keystroke will give late damper lift (thereby failing those points on the Technical Exam!).

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    Ed Sutton
    ed440@me.com
    (980) 254-7413
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  • 13.  RE: Under lever height

    Posted 02-25-2018 11:26
    I measured half-dip on a grand in my shop.

    10 mm dip, half dip = 5 mm
    45 mm blow distance, half-blow = 22.5 mm
    Half-blow for damper lift is 22.5 mm from the string
    Half-dip brings hammer to 12 mm from the string. Making it almost a 3/4-blow distance.

    One might note that at half-blow; not only is the damper lifting but the capstan/cushion contact point is (should be) be on the Magic Line.
    If the angle between the rep and capstan is a straight line at this time, then the friction between the two is also lowest to coincide with damper lift. Capstan angle has been discussed on other threads about whether it's better to have this interface friction lowest at damper lift or Let Off.

    Just some things to make you go... Hmmm.

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    Regards,

    Jon Page
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