About tuning pins and mounting strings

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About tuning pins and mounting strings

Postby Bob Lewis » Fri Oct 30, 2009 2:11 pm

Zither pins are sold in the USA as .198 inches in diameter, intended to be
suitably tight in a standard 3/16 inch hole (.1875), about a .010
difference. Both pins and hole size can vary slightly, so there must be
some allowance for tolerance buildup. If one was over by .005 and one was
under by .005, they would be the same. The reality is that they both stay
closely uniform, as long as the hole is not drilled with more than one
pass.

The circumference of a zither pin will take up approximately 5/8" of
string length.

Four (4) turns of a pin would take up approximately 2 1/4" of string.

Note that smaller diameter strings require slightly fewer turns, since the
center of the string is closer to the tuning pin circumference. Thus, the
high string pins do not need to be backed out quite as much, perhaps a
half turn on the top 10-11 strings (.018 and smaller) as a simple rule of
thumb. That would be significant only on a model B, whereon the final
height of the string meeting the tuning pin should be the same as that of
the bridge pin groove, theoretically optimizing the lateral force on the
bridge pin and looking more neat and uniform across the set.

Trimming all but 2 inches of excess string length still achieves about
four full turns of a pin, because the ball knot or loop will draw down
under tension and provide approximately 1/4" more string length, 2 1/4"
and four full turns in total.

What works quite well is to set the tuning pin to one inch +-1/16" from top
surface to tip of the tuning pin. Then trim all but two inches of string.
This will result in the tuned strings being in a suitable position range
where they meet the tuning pins.

To achieve the optimal height and a neat appearance, one should coax the
windings upward into a neat pack with no overlap. This is done with tuning
wrench in one hand controlling tension while poking the string windings
with a tool in the other hand. I use a small slotted head screwdriver.

A "becket hole" is the string hole in the tuning pin. Line up each becket
hole ready to receive a string and then sight across the row to double
check for becket hole height variations. Adjust as needed to get a
relatively uniform line of becket holes. If any pins seem loose, correct
that before starting.

A model A style instrument with vertical tuning pins can be problematic.
Usually the tunings should be set at a 3-7 degree angle to the plane of
the string's approach to the tuning pin (not the vibrating length).
Simpler automation makes the holes vertical instead. It is no different in
principle than how one would place tent pegs (assuming some camping
experience). The model A installation should have strings running at a
downward angle from bridge to tuning pin rather than straight on to the
tuning pin of a model B. If the becket hole is set too low, the string
will try to overlap other windings on the pin before the string is up to
full tension. Thus, one might set tuning pin tips to a full one (1) inch or
slightly more (off the top) before starting. On old vintage model A and
all luthier instruments except Fackeldey (Zephyr Hill) to my knowledge,
the tuning pins are instead set at an angle to accommodate the string's
downward angle approach and easily accept a string during installation.
Strings will try to quickly run down the pin during winding, so may need
to be controlled with a tool in the other hand.
Bob Lewis
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Location: South Carolina

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