Banjo Construction

11. The liner is made of ripstop nylon, to loosely fit the wooden form. Pin it around the form, and then
sew along the line of pins. It is big at the end of the neck, so that it can be brought back to cover the
outside of the case at the end of the neck. The plug at the end and a little bit of duct tape keep it in
place at the end of the neck.

12. The cover is made of coated nylon around the outside of the case. After the case is made, use
seam sealer on all of the seams. The only place water can get in is at the edge of the end cover, and if
the banjo is in a vertical position then the water can’t run into the case. Assembled with the liner inside,
the cover outside, and the banjo inside you can see where to trim the body end of the foam, liner and
cover. The cover and liner are then sewn together by hand.

1. The Banjo: Buy some “5/4” maple wood at your local Hardwoods store (1 ¼” thick before it gets
thickness planed). Mine was 1 1/16” thick. Cut out the neck in two pieces, so that the halves glued
together will be 2” wide for the widest part of the neck. I used a saber saw, but a band saw would be
better. It is helpful if the two pieces are laid out in mirror images on one side of the board, and glued
so that the same faces of the wood are against each other. This way, the grain is matched like in a
mirror, and possible warping of the neck is minimized. Glue the halves of the neck together with
woodworker’s glue like Titebond or Elmer’s yellow glue.

2. Cut the neck’s sides. I used a table saw, with small pieces of
wood taped to the side of the neck to guide the wood through
the saw at a slant and cut the correct paths of the sides. A
band saw would work well. A saber saw would do the job, but
give you more work in the shaping of the neck.

3. Cut the slot for the carbon fiber reinforcement rods. I used
an adjustable dado blade to cut the slot, but a router could do
it, too. Two rods 1/8” x 3/8” are glued together into the slot.

4. Cut out the fingerboard, and glue it to the neck. Then shape
the neck, except where it will attach to the body. It will be
easier to handle for the shaping if the body is not yet attached,
and if the frets are not in place. I had a “real” banjo to help me
copy the correct size and shape of the neck behind the
fingerboard.

scale drawing, click for a printable enlargement.
Click here for drawing with dimensions.

neck with slots cut for
carbon-fiber
reinforcement rods

Materials:

Seattle Fabrics:
1. Ripstop 1.9 oz. nylon for case liner (#FRU Uncoated Ripstop #3480)
2. Coated nylon for case cover (FC5 500 Denier Cordura, #3460)
3. ¾” Black Nylon Webbing (#0015)
4. Seam Grip Seam Sealer (1 oz) (#MCNSG)

top and bottom views
of plywood form for
making foam case

foam case ready to
cover

5. The body is glued to the neck in blocks, and then cut out with a band saw. The
armrest is cut from the same piece, so that it matches up against the body when
folded up. A saber saw will work, but give you much more work in shaping the
wood after it is cut, since it has trouble cutting vertically in such hard wood. The
pieces that hold the tuning devices are glued up into an end block, but not glued
into the body until the body is cut since you cannot insert a bandsaw blade
through a hole in the wood. Wood dowels and the aluminum axle for the tuning
devices hold it in place temporarily for cutting it out, and then the dowels are also
used in gluing it in place.
6. After the inside is shaped and sanded, the back and sides can be glued on, as
well as the struts for supporting the can.
7. After final shaping and sanding, I used musical instrument lacquer with finishing
methods I learned from Stewart-McDonald’s web site.

9. The Case: First, I made a form out of scrap wood that is the size and shape of
the banjo, with the neck’s 1 ½” x 1 ½” fir rounded a lot at the end and a little
toward the body. Wood pieces block out areas for the strings, armrest and bridge,
so that there is space over these vulnerable areas when the banjo is in the case.
Then tape some waxed paper over the form, to keep from accidentally gluing the
foam to the form.

Drawing of case plans

outside of case pinned
to form, and the sewn
inside of the case

10. The ¼” foam is laminated in two layers. I got it at a surplus store, as a pad for a sleeping bag. It is
helpful to have at least one piece of it going the entire length of the case. Everywhere else, make it so
that the seams of one layer do not occur in the same places as the seams in the other layer. Spray the
surfaces to be glued with 3M “90 High Strength Adhesive”. The areas not needing glue should be
masked with masking tape. Spray one coat, wait two minutes, spray a second coat, wait 5 minutes and
then stick the pieces together. It sticks right away, but after several hours it is much stronger. In some
places, the next layer can be prepared right away. Other places under more stress should be clamped
gently and the glue is allowed to harden more. Leave extra foam at the open, big end to be trimmed
later. After the cover and liner are made, the extra foam can be trimmed to fit the banjo. A foam
mushroom-shaped plug is made for the end out of a piece of one of those big foam “noodles” that are
used as swimming pool toys.

Blocks of maple glued up
to cut out the body,
drawing here

8. The tuning devices are made of aluminum. If the holes are started
with a center drill, it is possible to get the holes within .006” of where
they should be using your eyesight. A center drill is a wide drill body
with a short small-diameter drill at the end. I used a 6-32 gun tap to tap
the threads. A gun tap pushes the cuttings out the end of the hole, so
that you can use a variable-speed electric drill to tap the threads.

Comments?
Questions?