Yet another simple, very inexpensive banjo --  this one fretless:

I was sent 300 miles away, to Detroit last week on work assignment.
Looking for something to occupy my evenings in the motel room, 
I set about building a simple fretless banjo. The thing turned out 
much nicer than I'd imagined -- plays/sounds/looks great, is very 
light in weight & is a lot of fun to play. 

Everything needed to build this project in the motel room was 
packed into a relatively small cardboard box: cordless drill & 
bits, a few saws, sandpaper & files, etc etc, plus all the 
necessary parts for the banjo itself, which included: (Note: 
I've used metric measurements here, even though I generally 
dislike metric, largely for the sake of overseas readers.)

- Neck blank (55mm wide by  583mm long by about 21mm thick chunk 
  of mahogany veneered tulip poplar from an old bed headboard found 
  at the local Salvation Army)

- Any type of hardwood, for the "neck mount" piece: 55mm wide by 
  415mm long & the same thickness as the neck. 

- 267mm diameter (10 inch drum-head) kid's snare-drum ($1.50 at 
  Salvation Army)

- A six inch length of 20mm by 20mm by about 3mm thick (3/32 inch 
  or so) angle-iron to cut into the eight tensioning brackets. sells real brackets but they're not cheap.

- Eight banjo head tensioners from an old project. sells 
  these rather inexpensively. Note: you may not need the above two 
  items if your snare-drum tensioning system works ok -- mine didn't).

- One fiddle-type ebony friction peg (for the 5th string) (or a 
  less-than-$10 commercial, mechanical 5th string peg -- 
  also sells these)

- One set of Nylgut strings (they certainly don't have to be Nylgut, 
  but I deninitely prefer nylon instead of steel for banjos)

- Four inexpensive guitar-type tuning gears.

- A small chunk of any wood to fashion an arm-rest from. I used a 1/4 
  inch thick piece of maple salvaged from a load of slab firewood. 

- Small piece of any hardwood for the bridge (I happened to have 
  ebony*, so I used that)

- About 2 inch of fret-wire (to make the "zero-fret"). In lieu of 
  this, a groove can be made in the neck & a length of  small (a bit 
  less than "fret-height") diameter wire can be epoxied into it.

- A few screws, nuts/bolts etc.

This photo should answer most construction details.
I'll add additional constructions notes below.

Dimensions of tuning head: 53mm wide by 106mm long  (I reduced the 
head thickness to better accomodate the tuning gears shafts)

Width of neck at nut is 42mm. Where it meets the drum it measures 51mm.

Bridge dimensions: 70mm long by 14mm high by 5mm thick - tapered to 
2mm wide at the top.

String-length is 642mm.

Overall spacing of the four playing strings at the nut: 31mm.

Overall spacing of the five strings at the bridge: 51.5mm (I really 
like wide spacing). Of course you can alter the neck and other 
dimensions to suit your preferences. Because there is no tailpiece & 
the "outer" strings papproach the bridge at quite an angle, you need 
to groove each string-slot a bit deeper than normal to keep them 
from popping out.

Because the normal rock drum's head-tensioning rim extends above the
level of the surface of the skin head, it is necessary to bend down & 
fold-over that part of the rim so the strings can pass over. This is 
easy to do, just hacksaw two slots then (using a pair of Vise-Grips) 
carefully and slowly bend down this part of the rim outwards until 
every part of it is below the level of the skin head. After that is 
done, ensure (again with Vise-Grips) that the newly bent part
is equal to or less than the thickness (as from looking above) 
of the rim thickness -- this is done so that it will not interfere 
once the end of the neck is mounted.  

I drilled (& carefully de-burred/smoothed) a 3/16" (a little less 
than 5mm) hole that the five strings tie to (using bowline knots). 
This banjo thus needs no tailpiece.

The most "labor-intensive" part of this project is roughing out & 
shaping the neck. I'd have been better off if I could have done 
this at home instead of the motel room, but still, it wasn't too 
much of a deal - using hand saw, coping saw, "sure-form" type of 
hand-held wood shaper (they bite on the pull), files and sandpaper 
did the trick. Main concern here was that I didn't disturb 
nearby motel-room guest's, or get kicked-out of the place -- so I 
shut myself up in the bathroom for this relatively noisy process. 
Note that the underside of the neck (where your left hand's palm 
rests) need not be contoured that much.

Very carefully plot the location for cutting the rectangular "neck 
mount" hole so that the top surface of the neck itself is flush 
(at the same height) with the top surface of the drum-head. Try your 
best to make the "neck mount" fit somewhat tightly through the 
rectangular hole (by doing so, nothing need be glued here). 
As for actual cutting of the hole, I drill holes just inside 
from  each of the 4 corners & then, using a bare hacksaw blade 
and files, shape the rectangle -- checking the fit regularily.

The small block (at red "X" in photo) is not needed. It was just 
an experiment here. With some strings on & tensioned, carefully move 
the end of the "neck mount" up and down until the desired 
bridge-height, string-height/"action" is determined, then install 
a screw through the drum rim and into the end of the "neck mount".
If you goof up here, it's easy to relocate the screw.

The arm-rest is slicone-glued on. Works fine.

The ebony fiddle peg (for the 5th string) is quite easy to install. 
I don't own an expensive tapered reamer normally used to fit such 
friction pegs, but over the years have had great success using a 
series of flat-bladed screwdriver ends (you can even easily file 
the ends to match the taper of the peg),  file ends, etc (use your 
imagination) to slowly "worry" an approximation of the proper taper, 
once the guide hole (same size as the peg's smallest part) is 
drilled. Go slowly & test-fit the peg often. The nylon 5th string 
has very little "pull" so the tapered fit doesn't have to be very 
"accurate" to keep the peg from slipping. Failing this, an 
inexpensive mechanical 5th string peg can certainly be used. sells these for under $10.

* With metal strings, a dense, hard wood such as ebony might make 
too harsh a tone but after experimnentally using such an all ebony 
bridge with NYLON stringed instruments (not just this fretless one), 
that's all I use now! I believe that ebony bridges noticeably 
improve the sound of nylon string banjos. 

Dennis Havlena - W8MI

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