Not a banjo, but a canjo! Similar words. Let me explain the story.
Well, there was a poor old black man, who wanted to play a dark blues for himself, but he hasn't even a cent to buy a guitar...
Step 1: The Canjo and the Blues
All the things that was given by America to the world the blues is the most important - at least in my opinion. I'm not an American, that world is very far from me - mentally, of course, because geographically it's not so far if you live in the Middle Europe, in the Carpathian Basin - I could go to the States any time I want, but to be a yankee... it's not my business:-) But why do I mention this? Because not only an American guy may be a blues fan. I think you don't need to be a black man to feel, to understand, to love the blues, because they were the ancestors and the main holders of the blues-feeling, the "sorrows and tears on the strings". So I'm one of the European guys who might be a black, when he feels the blue... The blues is my "everyday bread", as we say it in my native language. And I've tried to play blues on electric guitar, on classical or jazz guitars, but my opinion is you can't grab the essence of the blues without a real home made "black" instrument like the cigar box guitar or a canjo. I've made both of them, the CBG will be published soon, but, because that project was a bigger one, and I have to translate the full documentation, first I'm trying to publish a smaller but similar project: my home made canjo I made of a Ballantines' can.
Step 2: How to Gather the Parts of a Canjo?
Have you heard about the "canjo"? The idea is very simple: be as poor as you can, have less money than you need, BUT be a man who is longing for a guitar to play blues. The story becomes very simple in this case: you must find anything you can use as a guitar. The appropriate location to find these parts is the garbage. And what is in it? Some empty cans (dog-food, soda, canned beef, or anything canned thing), some wooden planks or similar wooden material, some rusty nuts and bolts, perhaps wires or old and curly strings, vine bottles and nails. And this is your goldmine for a canjo, because, as a professional poor man, you know that the can is a good resonator to amplify the sound of the strings, a wooden rod may be a perfect neck to attach the strings with screws or bolts. Seek some nails to fix them together, and finally take a glass tube from a broken bottle to slide on the strings, and play!
Step 3: A Canjo Today: Parts and Tools
Well, this is the romantic poetry. Now try it to build with me - this is an easy and very useful project "for those about the blues":-) First: from garbage, or anywhere, take a can. I recommend Ballantines, because its can is a pre-builded guitar body itself. Then take some rod, a wooden stave, or any flat and long wood, some screws for wood, two metal strings (any adjacent! strings from a guitar), and a piece of steel or aluminium panel for the back string support. And last but not least you should get two tuning keys too; this is a modern add-on, but the correct tuning is not a luxus when you play even blues:-) Try to get a ruined kid-guitar as I did for those plastic keys, or ask old ones from your guitarist friend (or enemy:-)). Tools: almost nothing: a drill, sandpaper, saw and screwdriver. That's all. Let's go!
Step 4: The Resonator and the Neck
Look at the pics, they may explain almost the whole project. The Ballantines can has a cap and a cover. Remove them to get the can itself. Cut a neck-rod from your wooden plank, using your eyes. The lenght may be your span cca. 3-4 times. (Under 'span' I mean the distance between your thumb and small finger apart - sorry, I'm a non-native speaker, as it was seen before;-)). The width of the neck is cca. 2-3 fingers. If you want to attach 3 strings, it must be wider, but the traditional canjo is built with only 1 string. On the neck, where the strings run, I glued a thin hardwood sheet (birchwood) as 'tapping bar' to lift up the strings above the resonator - this is a plus five minutes, but with this lifting the strings won't reach the resonator even if you play on the upper area of the neck. When the neck is cut, drill a hole into its butt, and drill an other hole into the can butt, too, in the middle, measuring the rod as you can see on the pics. You will screw your wooden neck into this hole, and, after it, you will drill another hole into the upper part of the body and the neck together to fix the neck on two points to the body (or the can). These are visible on the pics.
Step 5: Keys, Tuning, Slide...
After (or before) carve a small flat part on the upper end of the neck, where the tuning keys will be attached to. Drill the holes for the keys properly, depending on the amount of the strings, of course. Then assemble it. Now you are almost ready. Don't make it too sophistically, because you are a poor old black man, who have not any tools except his pocket knife and a drill made of a twisted iron wire. BUT, if you want, you can mark the halftones on the neck to intone correctly. The normal guitar has metal frets, the lute and other early plucked instruments have gut made frets, but the canjo has only some scraps on the neck where the halftones are. And this is enough for the blues.
About the strings
The bottom string support is a small bent, drilled metal sheet, assembled into the butt, on the can, and fixed with the mentioned butt-screw. That is very important, the tension must push only the rod, the can is only a resonator on it, without any forces on it. When attached the strings, take a M4-5. bolt with nut, and put is under the strings as a bridge. And put a smaller wire under the strings at the keys, on the start of the neck. This traditional way is surprisingly efficient to send the frequencies of the sounds toward the resonator. The sound of a canjo is always a nasal-like, metal-echoed sound with smaller noises of the resonator. This is authentic...
The 'slide' and the tuning
Well, now you need a 'slide' to play - because the canjo can't be plucked with the "normal" way. The strings are tuned 'ad libitum', but it is a good idea to use them the following way: 2 strings: 'b', 'e' increasing, 3 strings: 'g#', 'b', 'e', or 'E', 'b', 'e', increasing. In this case this is a E-major chord, and you may slide the tones by a glass tube, making the typical blues-like scales by it, because this small extra tool will really slide between the diatonic notes. This is a wonderful sound when moves paralelly and never jumps out from the tonality. This is blues itself;-) This glass (or steel) tube must be a heavy one, because its mass will create the actual string lenght when playing, so even don't try wooden or plastic tubes.
Step 6: Ending
How to play? If you are a guitarist, try to play your blues scales with this extra sliding, and listen, listen, listen all the blues tunes always, and you will explore the ways. Or find old blues men on the YT, and watch them. And, if you are not a guitarist, just a fan? My advice is the same. Guys, listen blues, because the blues is poetry, force and the most confidental way to make sounds by some dead elements they call 'guitar':-)
(If you are interested, you can read it on original language <a href="http://tabulatura.hu/blasius/canjo/index.htm">here</a>).