A few years ago, I created a tool (a wheel) for myself to make it easy to transpose chords from one key to another. I wanted one because I transposed a lot of music I learned on the guitar into keys that better suited the ukulele (and my rather limited vocal range). Then I gave it away to any one else who could use it.
A bit later, I added another, outer ring to that tool to provide some musical theory content, because I was learning about it. It’s still available as a PDF for download, here.
At the same time, I started making a second tool: a chord builder wheel so I could figure out how to make chords on the ukulele. That’s what’s in the picture above. It’s another PDF with wheels you can laminate, cut out and assemble. The latest edition of the chord construction wheel is here as a PDF.
This wheel works somewhat differently, but is assembled in a similar manner (print, laminate, cut). This is the back of the main wheel – it’s optional, but I recommend you print it on the back of the main wheel.
Once built, first you align the key on the inner wheel with the root or tonic note on the outer (the capital “I”). The twelve notes on the outer ring represent the 12 notes in the western scale octave – twelve frets on your ukulele or guitar. The Roman numerals represent the notes in that scale and they match the notes on the inner ring, so in C the IV and V notes are F and G, respectively.
The Roman numerals are used as generic counters. So the root of a key is “I” (capital i) or one. You count up from that: II is the second note (in the key of C, this is D), III the third (in the key of C, this is E), and so on. In-between notes are shown as bII or bIII (flat 2, flat 3). These are noted in the chord formulae as Arabic numbers (1-3-5 is the same as I-III-V).
There are notated lines from the key note that run to the other notes in each chord. For example, the major chord (red line) runs from C to E and G: 1-3-5 (or I-III-V). Those are the notes you need to play to build that chord. For C minor (Cm or Cmin – the cyan line above the major) they are 1-b3-5 the b for flat (one step or fret lower): C-D# (or Eb)-G. There are 13 lines for chords. Some are three notes, many are four.
Around the outside ring are other musical theory elements. The relative minor is noted on VI. For C, this would be Am as the inner ring shows. The do-re-mi scale is shown, too, as are the notes of the pentatonic (P) and minor pentatonic (MP) scales. See the back for more musical theory notes and chord formulae.
I hope it proves useful and teaches you a bit of musical theory as you use it. Like always, you can use and distribute it freely, but I ask you to respect my copyright and not to reproduce it for commercial use or sale, or to include it in any products or packages for sale.
The entire chord construction wheel is here as a PDF.