Regulation bench bedding

[Farrell]

"I know you can't set dip out of the piano..."

Why not? Yes, a fine regulation should always be done in the piano. But when the regulation is way out and you have an action in your shop for repairs, I find it much easier to do the regulation on the bench. With old actions that are never going to be finely regulated, the bench regulation will suffice 95% of the time. For instruments that warrant a fine regulation, the bench regulation can get you 90+% of the way there, and it will just be touch-up in the piano.

First of all, you need a stable VERY FLAT bench. In a case like yours where you will be taking the action apart, measure string height at the ends and middle of each section. You can reproduce those on your bench exactly. Another thing good to do is to make sure the keyframe is bedded, and measure the key height of a number of notes, such as all Cs. Bed frame to bench and see if all Cs are the same height they were in piano - you can temp. shim key frame to reproduce key heights. Another thing you can do if you will not be disturbing the action rails, is to adjust letoff on one or two notes at the end of each section so that the hammer just touches the string at letoff. When you get the action on your bench, this will allow a double check of your string height measurement - after setting your letoff bar from your string height measurements, see if your section-end letoffs just touch the letoff bar.

I like working on my bench so much more than in someone's home, that I do the bench regulation whenever possible. I'm sure it is not always the most efficient way to go. If the keybed is not drastically warped, and you have a flat bench, you should always be able to regulate an action to within a 16th of an inch of letoff. That's been my experience anyway.

Terry Farrell
  
----- Original Message ----- 
From: "Keith Roberts" <kpiano@goldrush.com>
To: "Pianotech" <pianotech@ptg.org>
Sent: Friday, January 10, 2003 11:15 PM
Subject: Regulation bench bedding


I just replaced the brackets on a Y&C. I brought it home so I could do it on a bench that was the right height. I set my boards to string height and roughed in blow distance and jack position( 1/4" out). Started through letoff and the sharp dip was about right but the whites, the dip was so shallow the hammer rise was shy of letoff by 1/2". I know you can't set dip out of the piano and realized I should have measured the dip because now I'm wondering if the tech that wound all the adjustments out, messed with the dip so as not to break the jack off against the stop. In this case, the drop screws came up 3 turns and the let off buttons 5 turns. So now I'm thinking I should have shimmed the balance rail up to get enough dip so I could set let off. My aching back tells me I'm doing way too much work in the piano. It would be so nice to duplicate the bedding, so the amount of refinement in the piano was minimized. Dale Erwin said I could take sample dip reading of every C and shim the rails to duplicate the dip. 
Does anybody have any other methods? Would it be better to take the sample dip readings at the notes next to the bedding bolts.
Your thoughts please.
Keith R