About Checking

[David Ilvedson]

Go to http://ptg.org/    Click pianotech archives and search hammer checking.   Make sure your hammer tail shape is right...i.e.  a 2&1/2 to 3 inch radius.   Do the tails come down flat and then angle sharply in at about 25 degrees?  Wrong shape=poor checking.  The simpliest thing to do when you have existing hammers to deal with is take ruler or better yet a protractor and look at what circle with a 3 " radius looks like.    That curvature shape is what you are after, what the shape of your hammer should look like from the side.   Clamp a section of hammers up on a block so they are above the backchecks and you won't put undue stress on the centers.   Take a drill with a sanding disk and 60 sandpaper.   If you carefully run along the hammer tails you can duplicate that shape and make a BIG difference in checking.    1st even out the ins and outs of the hammer tails coming from poorer hammer hanging, then start bringing down the angle, smoothing it out.   

David I.


----- Original message ---------------------------------------->
From: "William R. Monroe" <A440WRMPiano@tm.net>
To: Pianotech <pianotech@ptg.org>
Received: Mon, 8 Nov 2004 20:11:55 -0600
Subject: About Checking

>Hi List,

>I've a small grand that I'm regulating (mine) and I'm struggling with
>checking.  Just finished regulation, and everything works well except
>checking.  Checking is nice and even throughout from a medium blow on up at
>15mm.  I've double checked things like:  repetition spring tension -
>definitely not too strong; escapement - jack is clearing knuckle
>sufficiently; backcheck height and angle seem right.  I guess my thoughts
>now lean towards, maybe backchecks are too low?  I can get checking on a
>soft blow by decreasing the checking height from 15mm to about 8 or 9, but I
>just don't like it that close.  Thoughts? and Thanks.

>William R. Monroe
>Madison, WI
>Assoc.


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