The diddley bow is perhaps the simplest of stringed instruments. They lack frets, and also only have one string. They are typically played with some sort of slide, although some players also use some type of mallet, or make sound by impacting the string with the slide itself. They are great fun to play. Some builder have hacked them together from complete junk, in a manner that they can build working instruments in minutes. I wanted mine to be slightly more sophisticated. Also, I wanted to include a basic discussion of winding your own pickups and some basic wiring.

Supplies

A piece of wood, around 36" long. An old 2x4 is fine. The one here was built of a 2x6, which was necked down into a sort of canoe paddle shape.

A guitar tuning machine--cheap off of an auction site. Mine was given to me by a local guitar shop. It was used, left over from a tuner upgrade.

A nut and saddle--something hard, that the string will be tensioned over. Mine here are built of left over beef and pork bones. People have used metal (ie, bolts), glass (small airplane sized booze bottles, regular sized beer bottles...)

If building pickups from scratch, standard plastic sewing bobbins work great. Otherwise, an electric guitar pickup. These can be purchased cheap from Amazon, or frequently can be free from any guitar repair tech.

Basic wood working tools--a jigsaw or bandsaw will make short work of the cutting. A belt sander will quickly remove grungy, damaged wood from recycled materials. I also inlaid the fret locations with copper nails (optional). My string tail piece was made from an old brass light switch cover. Some basic electrical tools--solding iron, potentiometer, 1/4" jack. You can skip the finish, or you can go all the way to a high gloss. I did mine in alternating linseed and tung oil. Gives the pine a nice glow.

I covered my wiring with some heavy copper foil. Looks cool (like an old moonshine still). Again, use whatever junk you have.

VERY thin wire--pickups require thousands of turns of wire. I used American Wire Gauge (AWG) 43. This stuff is just 0.002"--thinner than a human hair. 42AWG was used by Fender. A $15 spool has been enough to make about 10 pickup coils.

Magnets--the other part of pickups are the magnets/pole pieces. You can purchase or recycle AlNiCo magnets from standard guitar pickups, or you can go the route I did, and use small ceramic magnet disks. I would probably avoid neodymium magnets (ie "rare earth" magnets). These are very strong magnets--those chrome colored one--but they can be very shrill and hard on the ears. Ceramics are quite strong, produce a lot of volume, and were used extensively in the 50's and early 60's (and are still sometimes used).

Their are no rules here--I would advice, before purchasing anything, collecting junk and starting there. It's a fun project, and your friends will get a kick out of it. For example, I needed a knob for my potentiometer (volume control) so build one from an old shotgun shell brass. Sky is the limit--go as weird as you'd like!

Step 1: Neck and Body

The project begins with finding a suitable piece to build the diddley bow on. 2x4's are plenty strong. I found a 2x6 (pictured). It felt too wide and heavy for the project, so I cut it into a sort of canoe paddle shaped thing with a jigsaw. I wanted mine to look home built and slightly crude. The 2x6 was knotty, perhaps grade 2. Rather than hide that fact, I actually wanted to showcase it. In any case--use what you can find. I used a belt sander and an angle grinder with a sanding disk to clean up the rough saw marks and refine the shape. Then I used some finer paper by hand to get rid of most of the belt sanding marks. To make sure the knots were stable, I first used a few drops of super glue to stabilize them. After sanding, I finished the piece with several coats of linseed and Tung Oil Finish. Allowing it to dry over night, and sanding it out with some 220 grit paper. It's smooth, but shows some left over heavy sanding marks. It's fine. If you want to get fancy, go ahead and plane the wood, and finish as finely as you want. Or, screw it, just use the junky wood as is. Something cool about building it very crude. Again--no rules here. If it's strong enough to withstand the string tension, and it's around 36" long, you're good to go! If you do go with an oil finish--this is VERY important--dispose of the rags carefully. Linseed rags can become hot enough in curing that they can smolder or even catch fire!! I left mine out on the driveway in the sun overnight. The cured linseed is safe. Just don't throw them in your garbage can until they are dried and safe.

Step 2: Nut and Bridge

The nut and saddle are the components over which the string will be tensioned. These can be built from a range of materials. They should be made of something hard--you don't want the string to distort the piece or break it. I have seen these build from steel bolts, where the string rides in one of the threads. I have seen some interesting ones with the nut and saddle made from glass bottles, or sections of metal pipe. On mine, I built them for bone. (bone is often used on the highest quality acoustic guitars--the plastic pieces used in lower quality instruments are an effort to replicated real bone). Here, the bridge is a piece of T-bone from a steak, and the nut is a round bone left over from a ham steak. These were simmered in soapy water and given a good scrub to get rid of any adhering meat and grease. Looks cool--I really like that they are still identifiable as bone. Unlike a guitar or other fretted instrument, the string on a diddley bow is a considerable distance from the neck. Because of this, the nut and saddle need to be thick, or mounted on some type of platform to raise them up. In our case, the string needs to ride high enough to be above a pickup mounted under the string.

Step 3: Pickups and Wiring

I'm sure the reader has noticed that electric guitars have solid bodies, and are very quiet when played without amplification. Acoustic guitars, on the other hand, have a hollow body which serves as a sort of resonator. The volume they can produce is really just a function of the volume of air contained within them (ie, a cello is much louder than a violin). Our diddley bow is a basic 2x piece of wood. Without an amplifier, they are really quiet. You can feel free to use a standard guitar pickup. I find the configuration to be ugly, and I enjoyed the challenge of "rolling my own". I would recommend reading this excellent article from Make Magazine. I stole the idea of winding pickups on sewing bobbins from this article: https://makezine.com/projects/wind-your-own-guitar-pickups/

Briefly, a pickup is a means to convert the mechanical energy of a string (ie, the vibration of the string) into an electrical signal which can be amplified as much as required. They use a coil of wire--normally many thousands of turns--which is placed within a magnetic field. The strings become magnetized due to their close location to the magnet in the pickup. The vibration of the string causes oscillations in the magnetic field, and as the coil is also within the magnetic field, an AC voltage is produced. The voltage output is a function of both the turns of wire, and the magnetic field strength. Browsing a music supply catalog such as Stewart Macdonald will give you an idea of what's available. Here I am using Hobby Lobby variety 1/4" ceramic magnets and pieces of steel and iron as pole pieces. I chose 1/4" because they fit inside the plastic sewing bobbin perfectly. Ceramics are known to have a lot of voltage output in the pickup, and give rise to a hot, good, raunchy sound.

Pickups come in 2 basic varieties. One are single coils. A guitar such as a Stratocaster uses this type. The pickups is a magnetic field and a single coil of wire. They have a nice, clear, bright sound. I prefer the darker, heavier sound of a "humbucker" pickup--think Gibson Les Paul. The choice is yours. I've included write up of humbucker construction. If you prefer, just wind one coil and run it straight, as in the document, you can wire single coils either in series or parallel. Note in single coils, the magnetic fields and coil directions are the same. These are not hum cancelling, but do have a characteristic sound. Series wiring will always produce more output than parallel.

In the hum cancelling, or hum bucking configurations, the coil direction and the magnetic field directions are opposite of each other. "humbucking" generally refers to these coils being right next to each other, where as "hum cancelling" places the coils further apart. The middle pickup on a Stratocaster is reverse polarity/reverse wound from the other 2. In the diagrams, I have arbitrarily assigned "north" and "south" on these. The absolute direction does not matter--what matters if if they are in the same or opposite directions. Some folks test by using a magnetic compass. I just test to see if the poles attract or repel. If you wire up your instrument and it sounds very quiet, check the magnet directions, and if that checks out, make sure the coils are wired oppositely. (this is an issue with "phase". Sometimes, pickups are intentionally wired out of phase. It produces a weird gong like effect. See Peter Green's excellent "Green Manalishi", or Brian May's guitar lead on "We are the Champions")

You will notice I am using an actual coil winding machine. It's a hand cranked device with a 10:1 gear ration. If you're having to put 6000-8000 turns of wire onto a bobbin, doing it by hand can literally be an all afternoon event (I've done it--NOT FUN--NOT EASY). Pickup wire is very, very thin. Around 0.002" for AWG 43 (used here). The Make article used an actual sewing machine bobbin winder. Never tried it, but it seems to work. You can buy a spool of wire off of Amazon. I've used literally miles of Remington 43AWG and 44AWG, and have never had a single issue. I've snapped wire (my fault) but the wire itself works great. The voltage output will increase with increasing turns of wire. However, while the volume goes up, the frequency response goes down. I'm not sure if it makes a difference here, but a "normal" single coil has about 7000 turns of wire on it. I turned one of mine with 6000, and one with 8000. I put the 8000 turn coil closer to the bridge (to compensate for the lower relative movement of the string), and the 6000 further up.

Their are a number of videos about the mechanics of this.

Commercial pickups use eyelets to secure the wire to the pickup bobbin. I have mounted the bobbins on small pieces of perf-board. Or, as shown here, I have just wrapped the wire around lengths of stranded wire. the important thing is that the wire needs to be secured--it cannot move or bend when you're done. The wire is VERY thin and will not handle abuse.

Notice from the pickup winder, I have used 8000 turns of wire on 1 coil, and 6000 on the other. It is important to mark the start and finish ends of the coil, and also note which direction they are wound. In mine, I wound one with the top facing the pickup winder, and the other with the bottom facing the pickup winder. Alternatively, you can wind them the same way, and just wire one of them backwards.

Read the documents for details--in humbuckers, the magnetic field direction and the coil direction are opposite of each other. Before gluing or wiring anything, double check and make sure of the magnet direction. I test this by making sure if you put the two tops of the pickups together, the magnetic fields attract. This indicates one is north and one is south. The absolute direction doesn't matter--what matters is that they are opposite of each other.

After winding mine and checking conductivity with a voltmeter to make sure they are continuous, I apply just a drop of 5 minute epoxy to the leads and output wires. This will prevent movement or breakage of the leads. I have also wrapped my coils in a layer of standard red sewing thread, and coated that with a watered down white glue. The wire is EXTREMELY thin and will not handle abuse. The glue/thread serves as a decent armor against abuse.

Standard pickups can be adjusted for height (ie, distance from the string). I mounted mine by using thin wooden shims to adjust the height, and a drop of super glue to secure them to the wood. It works, but then to adjust the distance, the only way is to increase or decrease the height of the bridge.

A 250k potentiometer seems to work great as a volume control. See the image (taken from the excellent Seymore Duncan website). It shows all the relevant wiring--the pickups to the volume control, out through the jack. It also shows that the string should be grounded. The diagram shows the wiring for a single pickup--it works just as well with 2 singles or a humbucker.

Step 4: Holes for the Tuner, Potentiometer, and Jack. Cover Plates

A couple of holes need to be cut into the diddley bow. I don't have pictures of the process, but it's pretty self explanatory. I drilled a 1" hole in the headstock, and at a right angle, a hole for the tuning machine stud. I just eyeballed the distances. My diddley bow has a volume control. For that, I drilled a 1 1/2" hole most of the way through the body, with a small hole to run wires out the side. Finally, I drilled a hole for the jack. I connected the hole for the volume and the jack with a shallow groove. that allowed the wires to be flush with the surface. I had some left over aluminum sheet. It was easy to cut with some old kitchen shears. I used a circular one for the volume control, and a rectangular one for the jack. A few left over screws secure them.

It is important to have the string in good electrical contact with the ground. A string can act as a sort of antenna for noise. Also, an ungrounded string can make popping noises when you touch it. For this, I made the tail piece (to hold the string) out of an old brass light switch cover. Use whatever--as long as it's metal.

Also notice, in the end-view picture, that the t-bone used as a bridge is sitting on a wooden base. When I first set it up, the string was so close it was almost in contact with the pickups. The pickups aren't adjustable, so I had to jack up the bridge. Again--don't sweat it. Have a problem? Dig around in the junk, figure something out. This whole project is about repurposing cast offs, keeping costs way down...

It is good practice, with any electric instrument, to make sure wires are shielded in some way. You can use shielded wire if you have some. Here, I used copper foil throughout. It's easy to cut and bend, solders very easily, and looks cool. The area between the 2 pickup coils is covered in copper, to shield the wiring underneath. The gap between the volume control and the jack are also covered in copper. Finally, the tail piece is connected to the jack plate in copper.

If you don't have copper foil, you can do an ok job of shielding wire by twisting the pairs of wire with another piece, which is only connected at one end to ground. It's not great, but it works ok.

I secured the copper foil with copper upholstery tacks. Again, looks cool, gets the job done. Finally, I put a patina on the copper--this was carried out by dampening it with some horseradish (seriously! Horseradish has some sulfur compound that give the copper a tarnished look, including some greens/blues).

UPDATE: In my first version of this, I had the tuner installed on the side of the body, with the post coming in parallel to the fret board. It seemed like a good idea--but you can see from the original photos, I had to use 2 string trees to make the string go to the center line. Also, the string was yanking on the post at a sharp angle. The tuners were cheapo Ebay import models, but still, I broke 2 of them in about 3 weeks. In the last 2 photos, I'm showing my "repair". I plugged the original hole with a short length of old broomstick. I plugged the screw holes with short sections of bamboo skewers. To make it look fairly "seamless", I did an old carpenter trick. I installed them with super glue, then sanded, then more super glue and sanding. By the end, the sawdust and glue fill up any gaps. Then, I moved the tuner to the end. Since the 2x lumber would not work with the 1" tuner post, I used a back saw to carefully cut out the bottom of the neck, so the remaining part was 1/2" thick, and I cut it far enough back to allow enough room to re-mount the tuner. A hole was drilled for the post. This increased the distance between the tuner and nut, removed the 3 way turn the original model had, and I think it looks a lot less wonky than the original. I do not feel nearly the resistance, and I hear none of the grinding as in the first version. So, long story short, do not follow my original plan on this one. Good idea, doesn't work in practice.

Step 5: Finishing Touches

Most diddleys don't have any sort of fret position markers. I found it impossible to try and play without any help. I used more of those copper tacks to mark the locations. I marked mine with the Em blues scale on top, and the diatonic scale (like a dulcimer) on the bottom.

Notice on the picture of the bridge that the bone is propped up on wood. The bridge (t-bone) was too low, so the string was impacting the pickups. Some kind of slide is needed--a classic way is with a beer bottle. Bone or metal work great. Careful using something that can get damaged. A friend of mine tried using his phone as a slide--it left a deep gouge in the plastic.

From the picture of the nut, you'll see an eye screw, and another screw used as a string tree. I was having problems with the nut (the round bone) sliding under the string tension. The eye screw changes the angle of the string, and the regular screw inside of the bone holds the string down. It also shows an eye bolt driven into the head, so that it can be hung on a wall.

The final touch was making a volume knob out of an old shotgun shell. I cut it down to the brass, then filled it with epoxy. I drilled the epoxy to fit the volume pot shaft, and held it in place with a drop of super glue. Goes with the whole hillbilly redneck vibe I'm after.

Step 6: Have Fun!

I hope this was a fun project. I realize the details are pretty vague, but the builder is encouraged to use whatever they have on hand. That's most of the fun--cobbling up junk.

The pickups on here sound great. Nice an loud and clear. Hot enough to drive a distortion pedal.

You should be able to quickly plunk out some classics. I bet you could--even if you've never played anything--plunk out "Folsom Prison Blues" in under 5 minutes.

Since I am not a good enough player, I will cop out and direct you to watch the following vids. Justin Johnson is an amazing musician, and very serious about these primitive instruments. Seasick Steve puts a kind grungy country/rock spin. In any case, you can do a lot with just one string.

https://www.youtube.com/watch?v=JPOMYHKWGTE

https://www.youtube.com/watch?v=nreCw94lxPU