Jacob Doll action brackets

[Farrell]

Gordon might have the right idea, but you might get a stronger unit if you epoxy-laminate some hard maple together and cut them out of that on a band saw. I guess you could also take a hunk of Delignite pinblock material and cut them out of that. I shouldn't think if too difficult to do.

Terry Farrell
  
----- Original Message ----- 
From: "Keith Roberts" <kpiano@goldrush.com>
To: "Pianotech" <pianotech@ptg.org>
Sent: Friday, January 24, 2003 2:19 AM
Subject: Re: Jacob Doll action brackets


> I was thinking if I had the original specs or drawings it would help. Maybe
> Shaff can find them for me.
> >From my measurements, the hammer flange center pin is about an 1/8" to 3/16"
> high for a bore distance of     2 1/16" in the tenor and treble sections.
> That's kind of a short bore distance as you're almost drilling through the
> felt on the bigger tenor hammers. So I could cut about 3/16" off the front
> foot of the action bracket to bring the hammer rail down to same height at
> each bracket. The capstans have plenty of room to move down. I guess the
> whippen rail has risen about 1/3 as much as the hammer rail. So my second
> guess would be to cut about an 1/8" off the rear foot so as not to rotate
> the bracket and shim the wippen rail up and to the front until I have an
> action spread in the 113 mm range and the Magic Lines or lines of
> convergence are as close to the optimum as can be. The action spread now is
> 116.7mm in the treble and 116 in the bass. It doesn't look like these
> brackets are expanding at the same rate. Just the one treble bracket is
> showing a crack along the base.
> So now that I've moved the whippen rail to the front
> 2 to 3mm, I have to cut the back off the bracket or notch the keyframe and
> move the stack back in order to center the wippens over the capstans. The
> key ratio is 2.08 so the capstans are in the right place, I think. Then I
> hope and pray the strike line is back to where it should be and the brackets
> aren't jammed into the damper trap work.
> The hammers are hung at 5 3/16" or 132mm, center line to center pin.
> Renner has exact replacement whippens and shanks.
> The wippen number is 913 051. The shank/flange
> # 913 007. I hope someone is following this. If you know this action
> geometry,  is my scenario correct? The action seemed to have a spongy feel
> after I moved the whippen rail to the front. Is this because I compromised
> the wippen lever ratio by not moving the stack?
> 
> Really I'm hoping some one will have some in a drawer in their shop. Please.
> Keith Roberts
> kpiano@goldrush.com
> Associate PTG
> 
> 
> 
> > Make pattern, cast out of epoxy/epoxy composite?
> > ("Liquid Steel")?
> >      Thump
> >
> 
> 
> 
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