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MMD > Archives > January 1996 > 1996.01.19 > 03Prev  Next

RE: Problems with large 88 note rolls
By Matthew Caulfield

As Les Smith's first reply suggested, your problem is probably in the upper or lower brake pressure. The slippage problem does easily occur toward the end of band organ rolls, unless the tensions of the two brakes are adjusted just right--and this takes some fine tuning to accomplish. The difference in circumference between that of the take-up spool and that of the roll on the top spool is not large at the beginning of play, because the bare take-up spool is large and the band organ roll itself is equally large--much larger than any piano roll. But the difference gets very great toward the end of the roll, so that you have a very large take-up spool trying to pull paper off a small-circumference top spool by causing it to turn, the force required for which is much greater than it was when the top roll was large. The result is that the drive train, which keeps the bottom spool turning no matter what, causes the paper on the bottom spool to tighten up on itself, if there is any room for it to tighten, as soon as the force required to cause the self-tightening is less than the force required to pull the paper off the small-diameter top spool, which, remember, is restrained to some degree by its brake.

On a band organ, the other factors such as paper surface texture and degree of drag on the paper caused by tracker bar suction are (from my observation) minimal factors in the equation, although they may be significant factors in a piano roll situation.

Keep adjusting and you should lick the problem on all or many of your large rolls.

(Message sent Fri 19 Jan 1996, 16:56:11 GMT, from time zone GMT-0500.)

Key Words in Subject:  88, large, note, Problems, rolls

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