Showing posts with label head stop. Show all posts
Showing posts with label head stop. Show all posts

Thursday, July 9, 2009

Jackrail

The jackrail sits over the register gap and keeps the jacks from flying out of the instrument when the keys are pressed. Its ends slide into grooves milled in the jackrail support blocks.

I made the jackrail from a scrap piece of the quartered western red cedar used for the baseboard, and glued pieces of Alaska yellow cedar to the three visible sides. Then I routed a decorative molding along the top edges, using the same bit that provided the profiles for the soundboard moldings and bridge:


The jackrail is 3/8" thick. The ends were reduced to 1/4" to fit the jackrail support grooves.

On the underside I'll staple one or two layers of 1.5 mm felt cloth to stop the upward travel of the jacks. The cloth doesn't need to absorb the full force of playing the keyboard because the head stop under the keys takes some of that impact too. What's needed is for the jackrail to arrest any further travel of the jacks once the keys have stopped moving. This avoids the unpleasant feeling of the jacks hopping upwards, bouncing off the jackrail and landing back on the key ends, which results in an odd jiggling sensation under the fingers.

Sunday, August 10, 2008

Keyboard: Sharp reliefs and head stop

A little more tweaking of the keys today:

First I had to cut a little relief area at the back of the natural fronts. When played, the sharps rock downwards in a slight arc, and the naturals must be trimmed back at the junction of the heads and tails to keep the front of the sharp from rubbing. I scribed a knife line at 10 degrees and cut out that area with a sharp chisel:



I also discovered that the keys were rubbing a bit at their back ends. It seems that slicing through the green felt glued to the key ends with the bandsaw created enough fuzz to cause quite a bit of friction between keys, so I sanded the key ends again. That worked: the keys now fall downwards under their own weight, which they hadn't been doing before.

Lastly I stapled a 2-1/4" strip of thick felt under the key fronts as padding to limit the downward travel of the keys. This head stop is a typically Italianate way of controlling the key depth:


Right now the keys are all falling downwards because they are unbalanced, but eventually they'll sit properly.