How to Build a Cookie Tin Banjo

Introduction

You don't build a banjo out of a cookie tin because you're looking to add a professional-quality instrument to your stable of banjos. You build one of these unusual musical instruments because you like the idea of playing an instrument you built with your own two hands. The hardest part is finding the perfect cookie tin or metal fruitcake box to build your funky new banjo around. This post was contributed by my good friend Mike Gregory.

Materials:

• Neck Wood, 1 by 2 by 48 inch firring strips
• Cookie tin
• Small coping saw
• Rotary-Tool and metal cutoff blades
• Drill with 1/16th and a 3/8 bit.
• Hot glue gun and glue sticks
• Sheet-metal screws, ¼ inch by ½ inch long
• Phillips head screws, 3/8 inches long
• Rubber bands for clamping
• 100 and 150 grit sandpaper.
• Pencil
• Magic Marker
• Tape measure with inches AND metric markings
• Small carpenter's square.
• Phillips head screwdriver.
• Wood glue
• 5-string banjo nut (plastic string guide for the peghead)
• 5 eyebolts, ¼ inch by 2- 1/2 inches long.
• 1-1/4 inch wood screws, 2 each
• Fiberglas-reinforced strapping tape
• 2 Machine screws, 6/32 by 1-1/2 inch
• Nail or Icepick
• Knife with disposable blades
• Hammer
• #16 brass tacks
• Set of banjo strings
• 5-string banjo bridge

Step 1

Photo 3 by Lorna Wells

Select a cookie tin at least 10 inches in diameter. Cut the neck wood into two pieces, one 24 inches long and one the width of the tin plus three inches. One end of the smaller piece will fit inside the tin.

Step 2
Lay the edge of the cookie tin on the end of the shorter neck piece and mark the curve of the tin on the heel of the short neck piece. Cut the curve in the neck piece so it will rest securely against the inside of the tin at thje far end from the neck.

Step 3
Cut a rectangle the size and shape of the end of the small neck piece in one side of the cookie-tin. Slide the small neck piece through resting the hole and push the butt end against the opposite side of the cookie-tin. Drill through the cookie-tin and screw the end of the short neck piece in place. The other end should extend through the hole and 3 inches beyond the cookie-tin. Hot glue around the opening where the neck passes through the tin. Set the tin aside.

Step 4

Photo 1 by Mike Gregory

Sand the last 5 inches of the 24 inch neck piece flat on the top and bottom for the peg head. Glue two 1-inch wide strips of firring five inches long to the sides of the peg head. Wrap with rubber bands till set. Trim the edges of the peg head and sand them round. Drill four 3/8 inch holes for the eye bolts you will use for tuners. Make 2 holes at the top and two at the bottom of the peg head, far enough apart that your fingers can turn the bolts without bumping into other eyebolts.

Step 5
Sand the “ears“** and back of the neck smooth. Round the back with sandpaper except for the bottom 3 inches of the long neck piece.

Photo 2 by Mike Gregory

Step 6
Mark a line straight across the neck five inches below the top of the peg head. Use a square to make the line perfectly straight.* Cut a shallow groove in the neck with the coping saw on the line you marked. Measure and mark lines at the following distances from the first groove. Distances are in millimeters. Cut the second groove at 29.9 millimeters, 58.2, 85, 110.02, 134.00, 156, 177.6. 197.7, 216.5, 234.4, 251.2. 267.1, 282.1, 296.2, 309.5, 322.2, 334.1, and at 345.3 millimeters

Photo 4 by Mike Gregory

Step 7
Glue a 5 inch long 1 by 1strip to the left side of the neck between the 8th and 11th strip. Wrap with rubber bands and allow to set. Drill a 3/8 inch hole in the side an inch below the top for the 5th string peg. Screw a short slot screw into the top of the strip as a guide for the fifth string.

Step 8
Glue and screw the ends of the long neck and peghead piece to the 3 inch piece of the short neck piece that is sticking out of the cookie-tin. Allow the glue to set and dry.

Step 9

Octagonal Banjo - Photo by Roger

Screw two short flathead screws through the bottom (now the face of the banjo head) of the cookie-tin just behind where the neck enters the tin and near the base of the short neck piece. You may need to insert thin wooden spacers to keep from bending the bottom of the cookie-tin. Drive 5 brass tacks into the end of the cookie-tin. Don't drive them all the way in. Leave a quarter inch of the tacks sticking up to loop the ends of the strings around.

Step 10
Glue the nut into the groove at the top of the fretboard below the peghead. You may have to widen or deepen the groove to lower the nut so that the strings will be 3/16 inches high.

Colorful cookie tin back - Photo by Roger

Step 11
Wrap the threads of the quarter inch eyebolts with fiberglass tape and screw into the holes you drilled in the peghead and side of the neck. Put the lid on the bottom of the cookie-tin and hook the loop end of the strings over the tacks in the correct order and then string them down the neck to the appropriate eyebolts.

Step 12
Twist the strings finger tight. Slip the bridge under the strings on the head and stand it upright. Tighten a string till a clear note sounds. When you play the string open and then fret it on the 12th fret, the two notes should be in tune an octave apart. Move the bridge forward or backward to adjust the tune. When it's right, tighten the strings and tune.

Chief Designer - Mike Gregory

Technical Writer - Tom King

Resources:

1. CB Gitty Crafter Supply
2. Desert Rose Banjo: Intonation Problems
3. Lumber Jocks: Cookie Tin Banjo
4. PlanetGaa: GAA's Cookie Tin Banjo
5. IMF: Building a Cookie-tin (Backpacking) Banjo

Notes: 

Photo 1 - Mike Gregory’s ears being glued on
The ears go on square, and get cut to shape after. Since the client is paying extras, I used a maple slat from a discarded futon, instead of the usual plain firring strip.

Photo 2 - Mike’s Ladder stencil
“Since I mass produce cookie-tin banjos, I made a stencil out of scrap oak, and some aluminum bars and some brass bars. A 1x2 firring strip slips in, and a couple eyebolts with teenuts hold it steady, while the inked points of the casing wheel mark the frets.”

Photo 3 - Job well done
Completed cookie tin banjo by Lorna Wells, Tuscon Arizona

Photo 4 - Mike’s comment
Asked the client if he wanted a Danish Butter Cookie tin, for best sound, or an artsy picture of some classy broad. Turns out he's a broad-minded lover of the arts.

Photo 5 & 6 - Unusual Cookie Tin Shape
Roger , Much Wenlock,  England

Building the Banjo Coffin Case

Guaranteed to get you looks when you walk in with your banjo in this unusual case!

I was looking for a case for my long-neck banjo and a friend suggested this nifty, if somewhat disturbing, homemade design. The guys you jam with will love it - at least those that aren't totally creeped out. Banjos lend themselves to the traditional six-sided pine box style coffin shape. It's not hard to do and the effect is really cool in a Twilight Zone kind of way.

Materials You'll Need:

Sheet of 1/4 to 1/2 inch A/B-grade plywood*
2x2 x2' long board
Piano hinges
Foam liner material2 Strap hinges or piano hinges.
6 brass handles (for effect)
Wood glue/Gorilla Glue
Wood putty
Craft Glue
Plush fabric

Tools You'll Need:

Drill & bits
Circular saw or table saw
Miter box and saw or radial arm saw (better)

Straightedge, chalk line marker reel
Tape measure
Router

Making the Pattern

To lay out the pattern, just lay your banjo on top of the plywood and measure and mark the coffin shape shown at the right. Leave a little room for bracing and padding - an inch or so will do including the thickness of the sides and any extra padding you have in mind. If you plan to fly with this case, I'd advise 3 or 4 inches of padding all round. Airlines have an irrational hatred of banjos for some reason. Banjos don't survive air travel well. These how-to's assume a modicum of native intelligence, so I'll leave the exact dimensions of the top and bottom pattern to your own inspired guesswork.


Top and Bottom

The top and bottom will overhang the sides. Once you have the top and bottom cut, Sand them smooth, round or bevel the top and bottom edges with a router. Top and bottom will be the "A" grade side of the plywood since that's the side that will show. Measure the side pieces. Cut sides deep enough to accommodate the thickness of the banjo and leave room for padding the top and bottom. You'll be glad for the padding, if not for the weight..; Cut them 3 too inches long.Trust me you'll need the extra length.

The Sides:

The sides are the trickiest parts because the ends of the sides are going to have to be cut at just the right angle to mate up with the other sides. HINT: There are no 45 degree angles in this puppy. This is where a rectangular box begins to look like a much better idea, but if you can just soldier on through with your trusty speed square or your kids protractor, it's darn well worth the trouble. Test fit each side piece as you go to make sure the side angles match up. You CAN use math to figure the angles, but given my difficulty cutting an exact 35 degree angle with a table saw, I start with an approximate angle and then shave it down a bit at a time till the angles of the two sides match as cleanly as can be disguised with wood putty. Once the sides are all in place, go around and place piano hinges where the ends butt together. If the plywood is less than 3/8 inch thick, you'll probably have to bolt the hinges. Put the round bolt head on the outside and the nut on the inside. Saw off any extra thread. The nuts will be covered by padding when you're done. The hinges will give you good strong joints - you'll need them to support the banjo.

The Bottom

Lay the side frame on top of the box bottom and glue it into place. Before the glue dries, attach the bottom of the box to the sides using small thin screws every 4 to 6 inches. Predrill the holes to prevent the sides from splitting.Make sure you drill straight into the sides and not into the empty box. Once the bottom is screwed on, wipe off any glue that got squeezed out and let the glue dry.

Center Brace

Flip the box over so the open side is up.  Measure across the

the center of the inside of the box. Be sure to leave enough room at the "head" of the box for the banjo pot to fit inside.  Cut a 2x2 the width of the box, glue it to the bottom and screw it in place from either end. This brace will stiffen the center of the box and, when padded, supports the neck of the banjo just above the pot. Next test fit the lid to make sure the edges line up.  You may have to trim it a bit to make it fit snugly.  If you want to stain and varnish or paint the case, you can do it now and then apply the liner and hardware. If so, skip to the end and then come back to the next section.

Padding

Cut out two layers of block foam rubber or other padding material to fit in the two spaces at the bottom of the box. You can use a single piece and just lay it over the center brace.  If you'd like the brace more closely padded, simply take a strip of foam, lay it over the top of the brace and staple it down to the bottom of the box.  Next test fit the banjo on top of the foam and then place foam blocks at the strategic points indicated in the diagram.  This will keep the banjo from rattling around inside the box.  If you want to be even more slick, cut another piece of foam sheet to fit the inside of the box, then lay the banjo on it, draw the outline of the banjo onto the foam, then cut out the shape of the banjo.  Next lay the foam in the box and the banjo will sit in the cutout hole.  Cut another piece of foam the size of the inside of the box. Make it a half inch smaller all around.  Glue this piece to the bottom of the lid.  Make sure the lid will fit easily down over the bottom with the foam in place.  If you're going to line the box, leave a little extra room for the lid to fit down over the banjo.  At this stage of things is where you carve secret compartments in the foam for hiding capos, extra strings and emergency longnecks (Dr. Pepper longnecks, of course).  The foam keeps bottles nice and cold for a long time.

Lining

To give the interior a plush finish, buy a bunch of plush fabric in a color you like.  Get a big spray can of craft fabric glue.  Get the kind that doesn't melt foam rubber, but sticks to it and to fabric.  Cut pieces of the plush fabric to fit over the foam and up against the sides of the box.  Spray with craft glue, then press the fabric into place. You can cut and trim to disguise wrinkles and awkward fits.  Really hairy plush fabric is especially forgiving.  For the hole where the pot fits in place (if you did it that way), just let the fabric sag down into the hole. You may have to cut some wedges out around the hole to make the fabric fit.  I usually cut the pieces a little large so you can trim them down with an Exacto knife as you go. Cover the inside of the box with the lining and you're done with the inside.

Attaching the Lid

Set the lid on top and attach three hinges to one long side.  DO NOT DO LIKE I DID AND ATTACH IT TO TWO SIDES SO THE BOX WON'T OPEN (see diagram for placement of hinges and latches). The latches attach to two sides to insure the box closes securely.  You'll have to look around for the proper hinges.  I like shiny brass ones.  If you're on a budget you can install one handle as shown.  If you want to make it look really authentic, though, put three brass handles on each side. 


Finishing the Coffin

If you were good about sanding everything, you should be ready to finish the coffin.  Some people like to finish the coffin before all the hardware is in place. Either way I like to stain it with a wipe on stain and then cover it with a water resistant varnish or polyurethane clear coat.  Marine spar varnish is my favorite for giving it a nice shiny funereal look. Simply wipe on the stain you chose, wipe it off after it sits for a half minute or so depending on how dark you want the stain to be.  Let it sit and dry and then paint with thin coats of clearcoat.. Seven thin coats will look 7 times better than one thick coat with lumpy spots in it.  Give it a light sand with very fine wet sandpaper between varnish coats. 

All Done:

When you're done, load up your banjo and head for a nice jam session somewhere.  If you put six brass handles on it, get five friends to help you carry your banjo in pallbearer style. Always good for getting a reaction from the more genteel in the crowd.  Enjoy your new banjo case.


* Depending on how heavy you want it to be.  Go with the lighter wood if you don't want to risk a hernia carrying the thing. Banjos are heavy all by themselves.