Make a banjo

Lately I’ve been quite taken by string instruments, and collected four ukuleles, of different kinds, in a very short time (they’re so inexpensive!). I was going to acquire a fifth one, a banjo ukulele or banjolele, when I realized that I would save a lot of money if I made it myself from Chinese parts ordered over the Internet. A lot of waiting for parts, but about two months later the instrument is ready and it sounds awesome. This article will tell you how I made it while hardly possessing any luthier skill, in case you want to do the same.

I started by reading this article, which tells you most of what you need to do. Except that lengthening the neck looked like a lot of work, so I sought an even easier solution, if possible. I decided to use a tenor uke neck, but glue it to a concert uke fretboard, which is shorter. I also decided to use a largish hand drum (10 inches) rather than the typical 6 to 8 inch head of a banjo uke, so it would try to sound like the awesome (but expensive) 11-inch Deering Goodtime banjolele. Here’s the list of parts I ordered, current as of June 2017. With time the links will go bad, but hopefully you can still figure it out:

  1. 10-inch tunable hand drum (I got a used one for $12.62):
  2. Strings for banjo ukulele (high-G nylgut) ($6:90):
  3. Tenor ukulele neck ($8.49):
  4. Concert ukulele fretboard ($4.99): (warning: the fretboard was 2 mm too long up to the first fret, so it had to be sanded down; check its dimensions before you glue it on!)
  5. Tenor banjo (4-string) bridge ($2.38):
  6. Bone ukulele nut ($2.03):
  7. Tuning pegs ($2.81 for the set of 4): On second thoughts, I should have bought a set of closed-gear tuners for a few extra bucks, because the holes in the neck were too large for the pegs I bought, and I ended up having to make some bushings to take up the difference. The fatter pegs wouldn’t have needed that and they’d be better too.
  8. plus 2 hanger bolts, 2 adaptor nuts, and a 2-foot threaded rod from Menards, all 1/4 inch-20 standard thread, for $3.97 with tax.

So the total cost is a whopping $44.19, making it my second most expensive instrument 😉 Here’s a picture of the parts minus the fretboard, which took quite a while to arrive from Malaysia, the tuning pegs, and the tailpiece, which I made from a wooden paint stirrer:

The first order of business was to attach the neck to the drum. Here’s where the 1/4 inch hanger bolts come in. But before that a little woodworking is necessary so that the neck will clear the rim of the hand drum, and also because the butt of the neck is flat while the drum is round. Craig Johnson, who runs the machine shop back at work helped me with those, and also was kind enough to drill the holes for the hanger bolts on the butt of the neck and two diametrically opposed spots on the drum. The position and straightness of these holes is critical, so having a drill press and a skilled technician was quite a Godsend. In case you get the exact same parts on the list above, the first 1/4 inch hole goes at 0.876 inches down from the upper edge of the neck (on the drum, 0.856 inches from the playing side; you must disassemble the drum to measure this); the second hole goes exactly 0.85 inches down from the first, at 1.726 inches from the upped edge on the neck, 1.706 inches from the top edge on the drum. Here’s the neck after machining the butt and putting the hanger bolts on (one was longer than the other because of the extra depth available):

Craig was also kind enough to cut the threaded bar in two in order to make “coordinator bars” quite similar to those of a true banjo. The purpose of these bars is double: first they take the tension of the strings, which the round drum body would not be able to take without bending too much. The second is to bend the neck relative to the drum in order to adjust the “action,” or distance between the strings and the fretboard, after assembly. First you pass the hanger bolts through the holes on the drum, and fasten the neck tight with a washer and a nut, then you attach the long adaptor nut to each bolt, and a rod to the end of the nut so its other end goes through the opposite hole on the drum. This end is secured with a nut and a washer on the inside of the drum, and another washer and nut on the outside, leaving extra rod to install the tailpiece later on. Here’s a picture of what they look like once installed (you can enlarge it if you want):

I checked that by turning the end nuts differently on the two rods I could make the neck angle toward the drum head or away from it. But I didn’t want to get all the action adjustment from this for fear of warping the drum body too much. So I added some shims made of tape on the butt end of the neck right before final assembly so the neck would tilt backward, thus bringing the strings closer to the fretboard. Here’s a picture of the shims, which also shows the fretboard already glued to the upper side of the neck, and the linseed oil finish (five coats applied over a 24-hour period), which works great with mahogany:

Craig was again kind enough to make some brass bushings to make up for the fact that the tuning peg holes on the neck were a lot larger than the tuning pegs I purchased. The one part that was still missing was the tailpiece where strings attach at the bottom of the instrument. In the end, I decided to make a simple one out of a piece of a wooden paint stirrer from Home Depot (free). I made two 1/4 inch holes for the rods (the bottom one to accommodate a washer and nut as well) and four small ones near the top for the strings, which I threaded from the inside and secured with conventional string knots. Here’s the tailpiece, finished with a single coat of linseed oil:

Update: the wood of the tailpiece turned out to be too soft, so that within a week the G string had almost cut its way out of it, and the other strings weren’t far behind. They were impossible to keep in tune, too. Here’s a picture from the back side; you can enlarge it to see the details; the G string hole is on the right:

So this time I decided to attach the strings directly to the top rod, which the strings are unlikely to cut. I set some rod out of the adaptor nut and re-tightened the nuts, then made regular string knots to each string and slipped them onto the protruding rod. Thanks to the thread, the strings fell into separate grooves and I didn’t see the need to secure the free end of the rod. They tune really well because the tension of each string no longer affects the others. Here’s what they look like now:

And now to set it up for sound. After widening the bridge slots a little (don’t overdo it, but if you do, crazy glue is your friend), the bridge was placed at 1/2 scale length from the 12th fret (7.5 inches for a concert ukulele fretboard), and the nut set loose at the top of the fretboard (I sanded it down by nearly 1 mm since the action was too high on that end). Checking the difference between the 12th fret tone and the harmonic tone (put your finger loosely on the string above the 12th fret, but don’t push it down to the fret; pull that finger quickly as you pluck) allowed me to fine-tune the position of the bridge, which I marked on the drum head with fine pencil (do this after the the strings are tuned close to their correct pitches). There was an annoying rattle coming from the bridge when the strings were tuned, but it went away after tightening the drum head (do one quarter of a turn at a time, jumping star-like from one nut to another). Then there was a sort of general boom that muddied everything (I started from a drum, after all), which was taken care of by jamming a piece of foam lightly between the drum head and the first rod in order to dampen the drum fundamental note, leaving the harmonics, which mostly came from the strings, largely intact.

I won’t show you here the final picture because you already have it at the top of the post, right before I clipped the surplus string at the pegs, with a $0.94 second-hand belt added as a strap. Does it sound good? Here’s a sample taken with the crappy microphone on my computer:

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