Seems like this topic is one of those re-occurring, yearly topics which gets debated each and every year. If you feel that putting a crown in your leveling will make things better... by all means, go for it. If you don't, then don't. There's no love loss either way.
I remember talking with Eric Schandell at one of the Steinway seminars about this very topic. And his response was...."better be careful about talking about the mystical things done here at Steinway". This was one of things he was always trying to get a straight answer for and the only legitimate reasoning was the appearance of a straight line appears to slope, vs a crowned line gives the appearance of being straight. Everything else is smoke and mirrors.
As far as making a very nice crown key leveling stick, simply go to your local Home Depot to the Piano Technician department. Get a long U shaped aluminum stick in their trough of aluminum and steel rod supplies. I get the thinnest they have.
Cut the rail to the length of most keyboards. To put the crown in, simply sit in a chair and laying the rail across your thighs, with thighs spread about 18". With as even of pressure of both of your hands, start to put a very slight pressure on both ends. It doesn't take much to put a 32" crown. Check your work on a flat surface. If you bend it too far, simply reverse the procedure to the desired bend.
Also, this leveling devise doubles as a straight edge as the sides that weren't bent will remain straight. A two-for-one leveling device for under $10.
I was on assignment at a college and had forgot my leveling device. I made a duplicate in the parking of Home Depot in a matter of minutes. Cheap and easy...my preference for a good jig.
Tom Servinsky
----- Original Message -----
From: Susan Kline
To: pianotech at ptg.org
Sent: Thursday, October 14, 2010 6:27 PM
Subject: Re: [pianotech] key leveling with a curve
On 10/14/2010 6:08 AM, Horace Greeley wrote:
P.S. - But seriously, folks, if anyone out there _does_ have some _substantive_ documentation, I really would love to see it...at this stage, one less mystery in life would be most welcome...hg
Absolutely no documentation, whether substantive or smoke-and-mirrors, of any kind ... but I can tell you why I sometimes have used a small (subtle, you could call it) crown when leveling ordinary new sets of keytops on garden-variety pianos. I do it (when I do it) by having one side of my straight edge just slightly concave (from warping) and the other not. If I use the concave side, I reverse it a few times end for end, so that I'm assured of symmetry. And one can see a lot by parking one's eye at either end of the keys (in turn) and looking straight across the fronts, which I'm doing anyway by the time I get down to the yellow-.001"-tissue stage.
I'm sure we're all aware of something called "entasis" ... if the keys are (pardon me) dead straight, they look like they are not straight, but subtly sunk down in the middle.
Also, if one has replaced the b.r. punchings, (well, with the fluffy woven ones we used to use) they will probably pack down over time just a fraction more in the middle register than on the ends. Hence, if one puts a very small crown in the key leveling, it will probably end up a little closer to level a year or two later.
At the concert level, I found Al's Steinway-idea of uniformity of keydip to be logical.
Whether even the most picky artists will be bothered would seem to me to be dependent on how much crown one decided to use; but also on the artists' expectations about the venue, formed before they arrived. One's life is much easier if artists expect instruments (tuning, regulation, voicing) to be worse than they turn out to be.
Susan Kline
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