Skateboard Banjo
Project Plan
Use old skateboard decks to make the neck (and other parts) of a tenor banjo. A skateboard deck has a natural bend at the kicktail for the headstock making the underside of the deck a slightly convex fretboard due to the deck's concave. Skate decks are typically 7-ply Canadian Maple and are very stiff. I will be laminating two decks together for extra depth and stiffness.
- http://en.wikipedia.org/wiki/Banjo
- Hmmm, 5-string or Tenor? I'd love a 5-string so I'll try to make that work
- compare with commercially available, e.g. Ozark: 2102G 5-String Open Backed Banjo (Scale length - 697mm = 27.45")
- NB: I have no idea what I'm doing!
- neck: this is the skate deck part - I have two identical old decks (same pressing, same concave) which I've glued together with Gorilla Glue (see pics)
- body/pot: I'm going to use a wooden hand drum with tensioners which will give me a basic body for little cost and little work. In the future I want to glue up and turn my own rims on the lathe.
- bridge: current thinking - just a piece of skate deck
- nut: current thinking - just a piece of skate deck
- tuning hardware: ebay cheapest set of 6 guitar tuners 3x left 3x right
- strings: whatever becomes available
- tensioning bars: I'll see how the hand drum and neck come together
Geometry, plans and other info: -
| Banjo | # frets | scale |
|---|---|---|
| Gibson 26-1/4" | 22 | 26.250" |
| Long-neck 32-1/4" | 25 | 32.250" |
| Tenor 22-1/4" | 19 | 22.250" |
| Vega 27" | 22 | 27.000" |
- a Tenor banjo has 19 frets and a 22.250 inch scale
- http://www.stewmac.com/FretCalculator
| fret | from nut | fret to fret |
|---|---|---|
| 1 | 1.249" | 1.249" (nut-1) |
| 2 | 2.428" | 1.179" (1-2) |
| 3 | 3.540" | 1.112" (2-3) |
| 4 | 4.590" | 1.050" (3-4) |
| 5 | 5.581" | 0.991" (4-5) |
| 6 | 6.517" | 0.936" (5-6) |
| 7 | 7.400" | 0.883" (6-7) |
| 8 | 8.233" | 0.833" (7-8) |
| 9 | 9.020" | 0.787" (8-9) |
| 10 | 9.763" | 0.743" (9-10) |
| 11 | 10.463" | 0.700" (10-11) |
| 12 | 11.125" | 0.662" (11-12) |
| 13 | 11.749" | 0.624" (12-13) |
| 14 | 12.339" | 0.590" (13-14) |
| 15 | 12.895" | 0.556" (14-15) |
| 16 | 13.420" | 0.525" (15-16) |
| 17 | 13.916" | 0.496" (16-17) |
| 18 | 14.383" | 0.467" (17-18) |
| 19 | 14.825" | 0.442" (18-19) |
Here we have some progress photos of the deck lamination and slice-up. Note: "you can never have too-many clamps". Using bamboo chopsticks as dowels to align the bolt-holes, fill them in, and perhaps add a little strength.
The skate deck glue-up has been sliced down to about 95mm wide. The nose and tail beyond the bolt-holes are about 135mm and 125mm long. The truck bolt mountings are 59mm long each and there is 350mm between the innermost bolt-holes. The bolt-holes are 35mm between (46.5mm including holes).
The nut is to be located immediately before the kicktail starts to drop away. A centre line is scribed that also defines the location of the third string. The scale length will be decided when the hand drum is obtained and the neck-body join is decided.