Feelings ( slamming backchecks)

[Don Mannino]

Ed,

Yes, I agree with you that this can definitely be felt, and affects the "character" of the action from the pianists' perspective.

A quick test with the action out is to play the note and put the hammer in check, then drive the hammers into the backchecks. If the hammer tail is overly aggressive (very large sharp grooves on a short, small radius curve) and the backcheck angle is too steep, the hammers will not drive down much. Alternatively, if the hammer tail is too straight and smooth, and / or the backcheck angle is too straight, then the hammer will easily drive down past normal checking - this is equally as bad.

I like to have moderate roughness on the tail (as from 40 - 60 grit sandpaper on my sanding disk) with the backcheck angle set so that the above test allows the hammer do go down a little more but not too much - maybe a centimeter down with firm taps until it jams.

Another aspect to good checking in addition to what you mentioned is the springiness of the wire. Dead, bendy wires give poor checking and actually seem to affect the tone of the piano (crazy as that may be).  If the hammer tail / backcheck angle / wire stiffness are all right, the action will repeat best and feel very alive.

You have a sensitive touch!

Don Mannino RPT

> -----Original Message-----
> From: owner-pianotech@ptg.org 
> [mailto:owner-pianotech@ptg.org]On Behalf
> Of A440A@AOL.COM
> Sent: Thursday, June 03, 1999 5:29 AM
> To: pianotech@ptg.org
> Subject: Feelings ( slamming backchecks)
> 
> 
> Greetings all, 
> Can we talk about feelings? 
>   I have been thinking about backchecks. It seems that all 
> the lore for 
> regulating them, and the attendant tail carving to match, 
> have been with a 
> view for mechanical efficiency in the checking.  (Making sure 
> that the hammer 
> catches is important, imho, for without it, the repetition 
> spring is not 
> cocked and the resulting key rise on release will be slower). 
> However, is 
> there more refinement available than just making sure the 
> tail is always 
> caught?  I think so, and it results in a slight improvement 
> in "feel".   
>    Specifically, the feeling of the hammer hitting the check, 
> as it relates 
> to shock waves in the action train.  This became a factor as 
> I regulated an 
> off-brand piano that had had hammers replaced at some point.  
> It felt hard, 
> as in,  more than "crispness" in response.  The hammers 
> checked, but did so 
> by digging into very hard leather on the backchecks.  On 
> moderate to soft 
> play, I could distinctly feel the contact.  By shaping the 
> tail into more of 
> an arc, and bending the backcheck to intersect more properly, 
>  there was a 
> noticible "softening" of the touch. The hammers also checked 
> slightly lower 
> on hard blows, whereas before, they checked at the same 
> height, no matter the 
>  force. 
>      	This effect was slightly less than the change wrought by say, 
> mis-adjusting the up-stop rail, and about on a par with 
> replacing hard 
> key-end felt with softer material to mask the damper-lift.  
>    Anybody investigated this avenue farther than my three 
> cups of coffee?  
> Regards,
> Ed Foote 
>