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Pratt & Read keyboards

Posted: Mon Apr 20, 2020 6:57 pm
by filopantiLAB
Hi all!

I'm designing a replacement part for the infamous Pratt&Read bushings holding bar.
It's that sort of "rake" riveted onto the keybed assembly where you slide the rubber bushings in (left right on the image below):
bushingless_3.jpg
note: image from http://www.bustedgear.com/images/jobs/M ... less_3.jpg

Those hooks usually get tired, they loose their position and, in case of heavy finger players, they will snap off completely.
I've done my homework carefully measuring my Gibson G101 combo organ, and there is an uneven pitch between the rail hooks. They should be 13.65mm (quite close to 13.7mm standard distance between keys), all along the 61 keys. Unfortunately this is not true in the interval between Eb and Bb keys:
pitch.png
pitch.png (9.08 KiB) Viewed 2657 times
Do you ave any experience about this?
Could you share some measurements?


I'm doing this to restore my Gibons (lying in very bad shape), but I'm willing to buy not only one piece from a local workshop (to spread the tooling costs). If someone is interested, feel free to contact me!

Cheers,
Eugenio!

Re: Pratt & Read keyboards

Posted: Mon Apr 20, 2020 11:51 pm
by Ashe37
what are you planning on making it from?
why not 3d print it, at least for the prototypes?

Re: Pratt & Read keyboards

Posted: Tue Apr 21, 2020 6:54 pm
by filopantiLAB
Ashe37 wrote:
Mon Apr 20, 2020 11:51 pm
what are you planning on making it from?
why not 3d print it, at least for the prototypes?
It will be made from 1.5mm thick steel sheet.
Laser or water cut, then machine folded.

I think I'll skip galvanic zinc coating, and rely just on spray paint to rust proof the steel.
As per the original specs, after bushings install, the whole thing should be sprayed with anti friction paint (teflon based, I assume).

Aboout 3D printing: could be useful print just an octave of the "thing" in both versions (even and uneven pitch), and see what happens. Despite the fact that (now) I'm pretty sure that the spacing is that strange for some unknown reason, because the holes below the hooks also follow the hook's symmetry line. Old mistakes, clever workaorund, who knows....

I was just wondering id someone with a spare keyboard dismantled somewhere could confirm (or update) my guess.

Re: Pratt & Read keyboards

Posted: Thu Jul 30, 2020 10:26 am
by filopantiLAB
Hi all.

After a long and painstaking process I got my brand new "bushings holder thing"!
Several attempts were made, because of unexpected and somehow "humanly romantic" uneven measures here and there 8-)

As a result you can see some pictures of it:
completa_small.jpg
dettaglio_small.jpg
100% fit, with few pop rivets. You can replace in minutes without removing the keys: it just slides in place!

If someone is interested in this replacement part, fell free to contact me:

filopantilab@gmail.com

Re: Pratt & Read keyboards

Posted: Thu Aug 06, 2020 4:51 am
by V301H
I have had several instruments with Pratt-Read keyboards over the years. The only ones that the keystops (bushing holding bars) broke on are my two Gibson organs. The metal is a light gray color while later Pratt-Read keyframes are painted black. Possibly the metal used on the Gibson 60s Pratt-Read is less strong than later editions from the 70s and early 80s. On one of my Gibsons I took the keystops from a late 70s black Pratt-Read and replaced the original gray ones. It is still working fine four years later.