[pianotech] Wobbly artist bench

[pianoguru at cox.net]

Hi Anthony,

When I was a university tech, I had dozens of these MAFCO benches all over the campus.  Of course tightening everything is the first thing to do.  I found that the worst offenders were four large roundhead wood screws, one in each corner.  There was a little brass linkage, 2-3 " long, connecting the wooden frame on which the legs are mounted, with the metal height-adjusting mechanism.  These screw would very often be very loose, the threads nearly stripped, and the wood wallowed out so the screw would wobble quite a bit.  A bit of a wobble in these four screws translates to considerable wobble of the seat.  A bench in the condition, and pianists reaction to it, always created for me the mental image of a mechanical bull riding machine, mounted by a musician in tux and tails.

My solution to the four loose striped screws was to replace them with 1/4"x20 carriage bolts with two nuts.  The original screws are inserted from the inside.  The carriage bolt go from the outside in.  The second nut is a locking nut, allowing the first nut to be less than fully tightened, so the link can rotate freely.

Frank Emerson