Reply to: RE>>nuckle removal > Installation < Newton, The question of the nap direction of the leather on grand knuckles has always been arguable to some degree, but is somewhat academic. If one lays a piece of the leather flat it will feel velvet smooth with the nap and a little rougher against. The difference is quite easy to tell. However, it is much more difficult to tell which way the nap lies once the leather is glued around the knuckle core, for the simple reason that the nap tends to stand up. The 'lip test' mentioned by Jon Page is the best way to find out. We experimented by re-covering some knuckles alternatively in both directions, and also covered some with different qualities of leather.One that we did was of calfskin with no nap as it had a smooth shiny surface. As expected, it was unsuitable because of noisy return of the jack, which is unfortunate because the downweight was reduced by ten grams!. But I digress. Provided the different leather is of good quality there seemed to be little variation in the touchweight, both down or up. More significant may be whether the knuckles wear well without squeaking or grinding. We found that the more important friction problem is at the let-off point. If the key is lowered to this point, how much weight is required to perform the escapement? The jack and repetition spring only now begin to function, and a harsh let-off seriously hampers pianissimo playing. If the nap lies toward the hammerhead it favours the friction with the repetition lever, which is raising the knuckle. The jack does not move until the tender contacts the let-off button, after which it goes against the nap. Our findings are that there is a little less friction, (measured by averaging downweight and upweight and measuring the complete weght too) by orienting the nap toward the center pin. Renner knuckles come with a line pencilled on one side, and should be glued with this line towards the hammerhead. Every make we have checked has the nap lying towards the center pins, which is a confirmation of our experiments. As I do not consider myself an authority it might be in order to check with those who are; I suggest Dave Martin, manager and engineer of Herrburger Brooks (U.K.) who insists also that the nap lie toward the center pin. As an alternative, one might consider re-leathering the knuckles, provided the shanks are in good condition otherwise. We like the leather from Richard Meyer. The job is not difficult, my only complaint being cutting nice even strips to width, but there is a neat tool available from some leather outlets. I am trying to track one down as they are not that easy to find. It is called Jerry's Stripper. It has several utility knife blades, (which are available from any hardware store) which can be spaced to differing widths. A piece of leather can simply be pulled through to cut multiple strips. To clamp the leather in place the small size Pony spring clamps are ideal. The plastic tips are removed and discarded, then the ends bent inwards to conform to the shape of the knuckles. Ed Hilbert showed how in a recent PTG Journal. Cutting identical lengths off the leather strips is easily done with a felt guillontine. We like to make the pieces long enough to have a fold on each side like the Steinway knuckles, but this is entirely a personal preference. Regards to one and all, Ted_Sambell@banffcentre.ab.ca --------------------------------------
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