Kenneth Michael Guitars LLC
KMG "Success Kit" Rim Assembly part 3
Back edge contouring
Properly contouring the back of the rim can present some challenges. Again, an
understanding of what needs to be accomplished goes a long way to achieving
“Success". Note that the braces that are glued to the back plate imparts the “width wise”
contour to the back. The back edge of the rim imparts the “length wise” contour.
Because we precision form our sides using the inner most waist curve as the reference,
we are also able to pre-cut  the appropriate contour on the back edge. It should be
recognized that do to the doming effect of the braces and the rim, the inner most
portion of the rim waist curve is actually higher than much of the outside edge of the
rim. The above, unfortunately is another geometric reality that is over looked in almost
all guitar construction publications.
A back radius contour bar is included in the KMG “Success Kit” The two halves need to
be glue together. Allow to dry than clean off any glue and smooth the contoured edge
with a small sanding block.
Apply 80 grit sand paper to the contoured edge using 3M “77” adhesive. Cut a few slits
in the paper, than fold and secure the tabs to the bar.
Using the supplied leveling pins adjust
the rim clear of the mold with the back
edge up.
Use the contour sanding bar to mark
the contour on the neck and tail blocks.
Trim the end blocks down close to the
contour marks using a small block
plane or chisel. Remember the edge of
the blocks toward the inside of the
body is somewhat higher than the rim
edge. This in fact is another concept
that is easily over looked.
Keep in mind that the abrasive bar can remove material in a hurry. Start the contouring
moving the bar along the length. Work slowly keeping the bar as level as possible.
Mentally establish a center location than work the bar in a rotary fashion, again try
and keep the bar level.
The edge that is produced is spherical in all directions.
The process will remove material from the entire rim edge and both blocks. The kerfing
will blend into the sides perfectly
Bracing the Top and Back
Once the rim is contoured and the final
height of the tail block has been established
the 1 x 1/8" TB reinforcement can be cut to
length and glued in place.