<html> <body> Ric - I don't think wobble is the issue.  I think that any well designed checking system would compensate for a degree of lateral oscillation. The lateral hammer movement you sometimes see upon release of key is mostly due to an tail not parallel to its backcheck, or perhaps those designs which turn the backchecks at an angle to match the unsanded tails.  In either case, the hammer pinning can be compromised.  Keep remembering that, at the volume level involved in Wim's problem (we are still talking about Wim, don't you know) the shaking, rolling and rocking can't be the defining issue, as the extraneous hammer motion would still have to fall within an  expected range. As to the issue of adjusting spring strength to pinning friction... I had been introduced by Bill Garlick to the idea of accelerating the jack return speed by increasing the tightness of the balancier pinning, and the requisite increased spring strength for the same rate of hammer rise having the secondary effect of speeding the jack at the other end of the spring.  Remember, this whole process is meaningless on a non-butterfly spring system.  As is is, Ed Foote earlier said : <blockquote type=cite class=cite cite="">Jack speed is just not, imho, anywhere near the limiting factor in repetition speed Date: Tue, 14 Nov 2006 16:20:24 -0500 (EST) From: A440A@aol.com Subject: Re: [CAUT] Tight Jack Pinning </blockquote> Seeing the proper documentation, I would entertain Ed's theory in principle, except I would consider that the additional spring tension could be a positive factor in helping the returning jack in overcoming friction issues at the knuckle (mis-shapen, dirt, or rough buckskin).  The theoretical improvement of jack return would be an aid to fast repetition however, not for checking.  In fact, the combination of a high-friction/tension jack return system, combined with a lightly pinned hammer could contribute to the "fly-away" sensation Susan spoke of.  In that case, tighter pinning of the hammershank would be necessary.  The problem with a high tension rep-spring system is not necessarily the unpleasant 'kick' of the hammer rise, but rather the increase in resistance (friction) at the 'moment' of let-off.  As I tried to describe earlier in this thread (or its ancestor),  an imbalance between the force required to depress the key to the point of let off and that required to move it through let off will significantly define the characteristic of that action in pianissimo playing.  But all this is peripheral.  The main problem is that Wim has chosen to solve the problem by redefining it.  To wit: <blockquote type=cite class=cite cite="">Bobbling hammers means there is something wrong. From what I am able to figure out, there is nothing wrong with a hammer not checking. </blockquote> and <blockquote type=cite class=cite cite="">Nothing I have tried seems to work. So for now, I give up. But if anyone has another answer, I will be glad to try again.  </blockquote> It would be tragic to allow a thread which has generated so much attention to fade away with a WIMper.  Cheer him on or threaten him, but don't let him give up!! That's what he needs! Cheerleaders.  <div align="center"> <img src="http://www.ccom.ua.edu:16080/mjw/voices/cheer.jpg" width=350 height=228 alt="[]"> </div> Goooooooooh WIM!! Happy Holidays David Skolnik At 02:37 AM 12/19/2006, you wrote: <blockquote type=cite class=cite cite="">Hi David and Susan This is where I always end up thinking about this issue.  I envision that a hammer bouncing off at the high speeds we are talking about (even with soft play things are pretty fast) needs to not have any sideplay or wobble at the moment it contacts the check.  The check will try and hold not only a tail coming down into it, but one that is shaking, rattling, rocking and rolling :)  To.. it will generally have some sideways checking to attempt to hold. You can see this often on angled bored hammers that sometimes check and sometimes dont by watching closely for sideways movement when you release the check.  Perhaps when this happens some shear force gets into the picture between the <<<joint>> between the check and the tail and once broken and the tail gets moving sideways... it also releases in the vertical direction. I dunno when it comes down to it... speculation.  But firmer pinning always results in better checking IME. Dont know if I 100% agree about the stronger spring comment Susan forwarded tho.  You do have to at least watch out for the feel of the spring in the key upon release from check. Gets really annoying if that is too strong. Cheers RicB    I tell you what, David ... next time you have a good quality piano    which is offending in the checking department, pin a few of the worst    hammers to three swings and observe what happens. Then maybe you can    explain it to me. I just know that if I do it, I like the results.    Oh, and while you're at it, you might check the wippen flange and the    balancier pinning as well, and fix them if they're very loose. But    I've found that the hammer flange is the main problem, giving more    immediate results than the other two.    Best,    Susan </blockquote></body> </html>