I weigh shanks and separate them into piles to the .1 g. Then I measure the height of the knuckle, measuring the shank too (the shank width variance is negligible) but the knuckles are not always pressed in the same. So I further break down each weight pile into three groups: low, med, hi. I try to keep the variance within .010" (.25mm) and set aside ones out of the 'window'. I weigh the bored/tapered heads and plot their weights on a chart. According to the hammer weight, I'll select the appropriate weight shank to achieve as smooth of a SW curve as possible bearing in mind knuckle height groupings to place the med's more central and the low's and hi's at the extremes, screwing the shanks to the rail as I go. Grouping like-height knuckles leaves a more even let off button line and one less variable with note to note wippen/shank vertical placement (I know there's a better word for this). By assigning a specific weight shank to a hammer weight less SW adjustment is needed at the end of the process, ie; if the hi bass weighs 9.5 and the low tenor weighs 9, using the same weight shanks will leave the .5 g difference. But if you place a 1.7 g shank with the bass hammer and a 2g shank with the tenor you will come out with 11.2 and 11, respectively. Depending on the availability of sizes, you can strive for the same weight or a .1g difference. I then install the hammers and let dry, then remove them from the rail. Next is to cut the shank protrusion off with a band saw and rough cut the arc. Cut all tails to a even length ( I order longer moldings to accommodate a tapered bore) and sand the tails to a 3" arc. This produces a nice finished edge. Arcing removes about .3g. Now comes the final weigh off. Usually only 12 to 18 need addressing. I precut the hammer leads so I only need to look at the graph to install the appropriate lead. If material needs to be removed. I'll first look at the front side of the cove to remove a few tenths with a Forstner bit. I order sets uncoved as well; so as not to be hindered in the arcing process with a deep cove. The cove removes so little weight, it is not worth the effort in the scheme of things. FInally, easing the rear edges and bottom of the tail with a file. Reinstall. -- Regards, Jon Page
This PTG archive page provided courtesy of Moy Piano Service, LLC