page 19
For a more accurate neck alignment check, you must install
the cone, spider, saddle, tailpiece, and the two outside
strings. Before installing the cone, scrape off any glue residue
from the soundwell rim where the cone will rest, so the cone
will seat on a flat surface. Set the cone on the rim. Rotate it
until you find the point where it rocks the least; this is the
cone’s “sweet-spot.” Use a felt marker to mark the front of the
cone on center, pointing directly toward the neck
(41)
.
The legs of a new spider are seldom perfectly aligned when
resting on a flat surface. They need to be adjusted to fit. Using
double-stick tape, fasten four pieces of 3/4" plywood in a rec-
tangular pattern on your flat workboard, as shown in the
photo. Space the blocks so the spider’s legs are in contact
with the upper surfaces of the blocks, and then fasten 80-grit
sandpaper to these surfaces with double-stick-tape.
With a black felt marker, blacken the underside of the spider
on every leg
(42)
. You can follow your sanding progress by
watching the ink on the feet. One good sanding technique is
to sand in small circles; another good technique is to use a
clockwise/counterclockwise turn of the wrist in a short,
abbreviated motion. Use even pressure when sanding the
legs, until all the marker is removed
(43)
. The metal dust on
the sanding blocks will show you which feet need the most
attention.
Fitting the cone
Truing the spider’s “legs”
41.
Set the cone on the rim. Rotate it until you find the cone’s
“sweet-spot.” Mark the front of the cone with a felt marker.
42.
Blacken the underside of the spider on every leg.
43.
Use even pressure when sanding the legs, until all the marker is
removed.
