Decentring, Broaching and Centring

The tools required are shown below :

The levers to be recentred are stored on a thin board that slides between the check wire and the bridle wire.

Line up the decentring tongs, squeeze gently and then slightly release the pressure before squeezing again to press out the pin. Doing it this way will avoid catching the cloth with the pin and damaging or pushing out the bushing.

Measure the size of the original pin. In this case the pin is 1.25 mm. Since these levers have never been repaired before, this is the size used at the factory. The centres are in pretty good order, so a pin of the next size up will be used, that is 1.27-8.

The broach used is approximately the same size as the pin to be used. Make sure that the broach is perfectly straight and roughen the surface just the right amount, so that four or five passes will give you the necessary tightness of the pin. One way to roughen the broach is to roll it between a fine file and a hardwood (eg. beech) board. If the roughening is excessive, either use a finer file or gently remove the roughness by drawing the broach through sandpaper.

Test the pin dry in the bushing and then either draw it through the hair (not recently washed!) or smear it lightly with tallow. Knowing how tight the pin needs to be has to be learned. If the pin is inserted in the bushing at one side only, there should be no wobble. If you can't press out the pin by pushing the pointed end without pricking your finger, the pin is far too tight...etc. etc. Constant practice is needed and even the experienced workman needs to remember that the “knack” is just a memory, and like all memories it needs to be tested against reality from time to time.

Once you are satisfied with the broaching, grip the pin near the end with the nippers and position the flange so that the bushings are aligned with the birds-eye. This is also a knack that comes with experience. Push the pin through the wood while twisting it. The pin must be very firm in the wood but there should be no force needed to get it through. If you can't get the pin through without great effort and lots of creaking, you are using too big a pin and probably need to rebush, swell the wood and use a suitable pin. Such a case will only ever arise when the piano has been through the hands of a botcher before you.

When you push in the pin DO NOT push it right up to the wood but stop a millimetre or two before the jaws of the nippers touch the flange. Then let go and cut the pin flush while pressing the part so that the pin is extruded as far as possible when it is cut.

The nippers must be kept in perfect condition so that when the pins are cut the end of the pin is flat and shiny with a fine line exactly along its diameter. The quality of the workman can easily be seen from the quality of the cut. If he has taken no care to get his nippers in perfect flush-cutting order, he will have taken as much care with the rest of the job.