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Mill Speed Indicator

Mill stone speed was regulated by controlling the volume of water passing through the sluice gate. Tachometers such as this were belted to line shafting in the mill and the speed was manually regulated to maintain the desired rpm. Regulation of steam powered mills was usually accomplished by a governor, rather than manually. The wooden case measures 12x12x13. The glass is an old replacement (modern window glass). Otherwise, all original and good working condition.

The 6" wooden needle and maker's name "I.L. Davenport, Woodstown, N.J." on the face.

The 3" diameter wooden pulley with a groove for use with a round belt .

A hinged door gives access to the flyball mechanism.

The flyball mechanism, as used in early governors. The lower sleeve bears on a counter-weighted arm operating a movable rack which turns the pinion gear on the pointer shaft.

the tachometer belted to a horizontal lineshaft. Two small rope pulleys were used to make the 90 degree turn to the tachometer pulley. The 3/8" round belt tends to bind in these pulleys, causing the needle to jump. But, if the rope pulleys were replaced with free turning V pulleys, preferably with ball bearings, the tachometer would work well to monitor the speed of this lathe. Also, a 1/4" round belt would be more flexible and run more smoothly. A handheld revolution counter could be used to lay out the new scale on a paper or card to overlay the historic scale on the tachometer. Also, 4 concentric scales could be made to match the 4 pulleys on the lathe -(A project for next summer).

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