[ This article is just one topic extracted from a longer email I got

 [ from Jim.  Forgive me if it seems clumsy in spots; I'm not very

 [ familiar with the technical jargon.  -- Robbie



Grinding a musical box cylinder with one end in the chuck and the

other in a female center at the tailstock has dangers; if at any time

in the past the arbor has been dropped and it landed on the pivot at

the wheel end (the wheel is the heaviest part of the arbor so it's not

unlikely that it will hit the floor first), the tip of the pivot can

be distorted and cause the cylinder to move in and out as it revolves.

Apart from covering the lathe-bed with grinding dust, the cylinder is

not going to be accurate.



Instead, the cylinder should be reassembled and supported on the

parallel part of the pivot on V blocks.  Using a highly modified tool

and cutter grinder, turn the cylinder slowly by hand against a fine

grit wheel spinning at its rated RPM.  This finishes the pin length

very accurately to the pivots.  Getting it dead parallel is a whole

new ballgame but for accuracy it needs to be done.



Original pin length is a starting point, to compensate for the

reduction of length of the original comb tips (normal wear, more damage

caused by a run, etc.).  After re-profiling the comb tips you'll need

to leave the pins longer, maybe between 0.005" and 0.007".



Cylinders made by Falconnet or Lecoultre have cylinders that turn

slowly and have very short pins.  The comb tips in the treble have a

very shallow depth to the cylinder pins, even very slight eccentricity

here can spoil the music.  I repinned one recently; pin length was just

over 1/64".  With pins this short you don't get much of a second chance.



Raking (setting all the pins at the same forward angle) is a whole new

ball-game.  Necessary (some restorers say no), but you have to ask

yourself why, in such a highly competitive market, would manufacturers

add another stage to the manufacturing process.



I've been repining cylinders since the 1970's.  Have I made mistakes?

Hell, yes, after the last 40 years I have, but putting things right is

a strong and steep learning curve.



Jim Weir

Kirriemuir, Angus, Scotland



 [ A nice interview with Jim Weir in "Ezine@rticles" can be viewed at

 [ http://ezinearticles.com/?&id=208659  -- Robbie