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Sprunghub

Lazy closure on 'A' note/button

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I have a problem with the most commonly used 'A' note on my Crane ( 2nd row right side)....on the pull it 'starts'/sounds/stops as it should......but on the push it closes somewhat 'lazily' and continues to sound whilst 'dying'.  

 

The lever and pad seem fine.  I have replaced the spring in case it was weak.  I have not removed the reed tray to examine the 'inside' faces/reeds/valves pending advice. 

 

It is a 55 button instrument and there are no other / similar issues on any other buttons.  Is there a likely 'obvious' cause ?  In general it gets 'lost' in the playing but it is irritating and if it fixable in the hands of someone with rudimentary fettling skills I would like to resolve it.

 

cheers

 

N

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Hi,

I had a problem like that with my Crane, too.

The fact that the "ghost" note occurs on the press but not on the draw would indicate that the pad is not seating properly. On the draw, the negative pressure inside the instrument sort of sucks the pad into the hole, but on the press the positive pressure lifts the pad enough for just a little air to escape.

So replacing the spring, to pit more force against the internal pressure, was a logical thing to do. But since that didn't work, perhaps the problem lies in the pad having shifted from its original position, possibly through inadvertent bending or straightening of the lever. If this is so, the circular depression in the pad, which is caused by the edge of the hole, might be admitting air. Check that the impression on the pad matches the hole.

Another possibility is interference from a neighbouring pad. My Crane has "only" 48 buttons, i.e. two less on the treble side than yours, but the pads are still pretty crowded round the perimeter. It could be that a slight change in the alignment of a lever has caused two pads to touch ever so slightly, so that the closing force of the spring is dissipated by the friction between them. Again, check the alignment of the levers.

 

Hope this helps,

Cheers,

John

Edited by Anglo-Irishman
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Thanks John......I am 99.9% certain it is not an interference issue.....but it is a long lever, so that seems favourite, some misalignment.  I will have to go in again. 

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Is there any chance the button is slowing due to friction from the end bushing? Humidity can cause the bushing to swell.  And when you take the spring off and rock the lever by hand is it smooth?  Is there any chance the lever has bent sideways slightly so the button has a side load. To check this, make sure any sideways wobble in the button travels through the vertical point. Another way to check is put the end back on, put a few bolts through to make sure it is aligned, and then lift it off as vertically as possible and examine the button to see if it is straight.  The replacement spring, is it adjusted to be strong enough? Increasing the preload to see if the problem is resolved can provide a good clue.  Is the seat absolutely clean? The push/pull imbalance in sealing can overcome small seal issues on the pull. 

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I would definitelay agree that it sounds like a bushing problem. Try (1) Removing the grill to get access to the bushing board; (2) Insert the pointed end of a pencil into the bushing, and work it around a bit; (3) Perhaps even put a bit of the graphite from the pencil "lead" onto the inside surface of the bushing;

(4) Reassemble. That should do it.

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Thanks again for the above.....I seem to have fixed the problem.  The back story to the instrument is that it had a 'lot' of work, major work in some respects, realigning of levers, replaced posts etc done some time ago by a 'top' Uk restorer and although I stripped my little 35b box down to parts and rebuilt ends and re-tuned it from scratch (with assistance/advice from the Forum)  this thing makes my hands sweat/shake every time I have to take a screwdriver (actually a Feeler Gauge!) to it.

 

As it happened, I had over-ordered on the pads for my 35b by a couple so I had one spare from Mark L-A sat in the cupboard.  For the smaller instrument it was a mm or so larger than those used on the 55b, 15mm as against 14mm ? but, as the other 29 pads on that end are 1mm or so smaller, there was adequate room for the 'one' larger one.

 

It appeared that the pad was marginally 'off-centred', so I have replaced it with the slightly larger one and re-centred it and whilst not being too adventurous until the glue goes off, it now, pending a proper test, appears to be resolved.   

 

I have re-pressed the bush as advised too and left a bit of graphite on there so fingers are crossed and will no doubt be again once I start trying to find my notes.

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