Friday, February 16, 2007

Jacks and Jackrail

The jackrail keeps the jacks from flying out of the instrument. It also determines the keydip--the amount of downward travel the keys will have. Here Angelaa bastes layers of felt together which will go on the underside of the jackrail.

Here Jessica does some voicing on a plectrum. The thinning of the plectrum is done on the underside. You can see her holding the jack upsidedown.

The jacks are all too long. We need to shorten them by cutting off the tops. After careful measuring to determine the proper keydip, Karen uses the tablesaw to trim all the jacks. Note the ear and eye protection.

You can see the black mark on the jack which shows where the cut will be.

Here Roman is inserting a woven felt damper in a jack. The felt must be low enough to stop the vibrating string when the jack is at rest, but not so low that the plectrum cannot slip under the string after a note is played. About 1/32 of an inch is needed. The felt is cut in long strips which makes it easier to insert in a slot on the side of the jack. The strip is then trimmed off and the jack is tested and adjusted as needed.


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