HOW I BUILT A CELLO-BANJO FOR $41.50

Long ago a friend had a 4-string cello-banjo & while I much appreciated
it's deep melodious tone, my interest was in the 5-string banjo. At the time
I mused a bit about adding a 5th string to such an instrument, but I never 
got around to doing that.

Now I see 5-string "cello-banjos" becoming popular (personally I think the name 
"bass-banjo" would be more fitting) I hear some truly excellent cello-banjo playing 
on Banjo Hangout & youtube --- one fellow's absolutely incredible low-banjo 
clawhammering on "Bonaparte Crossing the Rhine" on Banjo Hangout (click) 
put me over the top -- I HAD to have a banjo that played an octave lower! 
Being short the thousand dollars to spend for a commercial jobbie, I, as is my apt, 
set out to see what couldn't be built out of "available parts" -- thus this article.

This instrument was easily built in 5 days of spare time.
CLICK HERE to see a YouTube video of this cello-banjo being played.
Here are a couple of photos that will help understand the construction better.
Other than string-length, neck angle & fret-placement, not much is fussy or critical.

A quick breakdown of the cash outlay:
- Rock-n-roll type 13" wooden shell drum (Salvation Army for $1.50)(I often see such 
  drums at Salvation Army, Goodwill & other resale shops) Any similar drum diameter
  should work fine.
- Maple, for neck -- from an old bed-frame - free
- Four guitar-type tuning gears - $8 total from
- 5th-string tuning peg - $8 from
- Commercial Cello-banjo strings - part # GTCB5-M  $19 (ouch) from
  (when I have more time, plan to experiment using regular classical
   guitar strings -- I'm SURE I can beat this $19 price!) 
- $5 worth of fret-wire from 
That's about all that's required other than a few screws & minor odds/ends!

Tools needed:
As with most of my projects, everything can be built using just hand tools,  
altho some power tools would surely speed things up.
- carpenter's type handsaw
- a thin-bladed saw is needed to saw the fret-slots to the appropriate thickness. 
   I have a real fret-saw somewhere around here but do you think I could find it for 
   this project - no! 
   So I used a simple kind of Japanese backsaw that worked perfectly --
   experiment on scrap to get the proper width so that the frets fit tightly.
- drill and few drill-bits
- a good yard-long straight-edge
- hammer
- a file, also some sandpaper 

A) Remove all the hardware & heads etc from the drum.
Cut all around the drum shell til you end up with something that looks
like a banjo body. The thickness is not critical. Then re-mount the tensioning-rod 
"screw-ins" on the newly cut down shell. Make sure that there will be no conflict 
between the head's metal rim & the "screw-ins" when the head is tightened. Instead of 
the tensioning rods which tighten the heads when it was a rock drum, I used 
hardware-store bolts of the appropriate thread & length (easy to find).

B) 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 (in my case 65 mm of the rim) so the strings can pass over. This is easy to do,
just hacksaw two slots 65 mm apart then (using a pair of Vise-Grips) carefully and slowly
bend down this 65 mm 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. You may 
ask why not just cut off this 65 mm section -- my answer is that it provides at least 
rigidity to help keep the rim/skin tight.   

C)  The "drum/neck mounting piece" fits through a rectangular hole CAREFULLY 
cut into the side of the drum (see photos). 

My neck is made of hard maple. Overall it measures 493 mm long (this includes the tuning 
head) by 55 mm wide at the right end (where it first meets the drum-body, 40 mm wide at 
the nut. The part of the neck that comprises the tuning head measures 56mm by 130mm. 
The neck I used happened to be 21.5 mm thick. The "drum/neck mounting piece measures about 
408 mm long by 55 mm wide by 21.5 mm thick. These thicknesses are not that critical as 
long as you cut the rectangular hole in the drum-shell accordingly (making sure that the 
neck surface is more or less level with the drum-head surface). Round off the bottom of 
the neck where your palm will rest while playing. The amount of "roundiness" is not 
that important - in fact, it's probably better to round it off too little than too 
much -- whatever's comfortable. DO NOT round off the bottom of the part where the 
tuning gears attach. Also DO NOT round off the last 87 mm of the neck (where it 
screws onto the "gourd/neck mounting piece")
PS: I suggest cutting the fret-slots before the bottom of the neck is shaped - it 
sets better.
First off, shape the end of the neck to match the inside curve of the drum. 
Carefully plot and measure how the "drum/neck mounting piece" should be 
positioned in relation to the drum (refer to photos & measurements) & then 
fasten the neck (accurately but temporarily) to the proper part of the drum/neck 
mounting piece using three hefty wood-screws (screwed in from the bottom) --  two, 
next to each other, on the "left" side (to better resist any upwards neck pull) & one 
screw installed closer to the drum body. Pre-drill everything nicely & make sure 
these screws don't protrude through the neck into the fingering area. I very 
successfully did not use any glue here -- the screws by themselves are amply strong.  
Another point - keep the end of the neck 1/8" - 1/4" or so from the drum rim -- 
to allow drum head/rim clearance.

Once the "drum/neck mounting piece" (with neck firmly attached) fits nicely through 
the rectangular hole, it's time to set the neck/drum-head angle. This is quite 
easily accomplished by very careful placement of a nice stout wood-screw, 
passing through a hole at the end of the drum's side and into the end of the 
mounting piece, at the far right end of the instrument. Getting this angle 
right is quite important to the ease of playing this banjo. 
Now remove the temporarily installed neck & get ready to mount the frets.

Don't let this prospect intimidate you -- anyone can do a fine job with 
just minimal forethought and care. On this cello-banjo, there is no need for a 
fingerboard as such -- the frets are mounted directly onto the top surface 
of the neck itself. I placed a single layer of masking-tape over the entire 
neck before I plotted where the frets-slots should go. Refer to the photos 
for the measurements as to just where to place the frets. Make the fret-slots 
deep enough, but not too deep - lest you weaken the neck. If ever there was 
a time for experimenting on scrap, this is it! The most important thing being 
to make the fret-slots the proper width -- not too tight nor too loose. 
Experiment! It's pretty easy.  When sawing the frets, you might use the 
simple jig I built that made the job duck-soup easy (see photo-2 above).  
Carefully measure & cut each fret. File the ends of each fret maybe 
45 degrees, then carefully tap them in. Once mounted, very carefully file the 
ends so no snags remain. Be extra vigilant that you don't file the neck wood 
while doing this. When done, lay a good straight-edge at various spots along 
the length of frets -- any high spots will become very obvious -- usually just 
requires a slight tap to settle things. I am not fond of conventional "nuts" -- 
The simple method here is a variation of my "brad nut" system. that requires 
mounting a fret where a nut would normally be located (see photos).

Drill for and mount the four guitar gear tuners as per photo. Then 
carefully locate and drill the hole for the 5th string tuner. Taper this 
hole properly, for a nice tight fit -- I highly suggest experimenting a 
few times using scrap hardwood before making the hole in the actual instrument. 
First drill the guide hole. What I then did was to find a non-Phillips-head type 
screwdriver whose blade end was the same taper as that of the 5th peg shaft. 
If I hadn't found this onewith the exact taper, I would have taken a wider 
screw-driver blade & ground or filed it until it was the proper taper. 
Carefully worry thehole larger until the 5th peg fits very snugly.

What have I got against conventional nuts you might ask --- plenty! In my 5 decades
of musical adventure, if I had to point to a single reason prospective musicians give
up playing it'd be because of a nut on their guitar or whatever that was too high! 
Seiously - I've seen this countless times -- even amongst people who should know better!
Folks often are very concerned about their action being too high, but many,
even experienced musicians, fail to fully realize that their string's nut is very often
the real culprit. Not nearly enough attention is paid to proper nut adjustment.
Darn things are just too fussy & buzzy & pinchy all the way around. Throw em out & 
let's come up with something better I say. 

Speaking of "action" --- action and bridge heigth are controlled on this instrument
by the proper positioning of a single stout wood-screw -- the one at the far right 
end of the instrument (as pictured here), that goes through the drum-shell and into 
the end of the "drum/neck mounting piece". 
Once the rectangular hole in the drum-shell has been cut, with the neck solidly & 
'straightly' screwed to the drum/neck mounting piece & inserted all the way thru the 
rectangular hole, then it is time to set the action/bridge-heigth. To put it simply, 
experiment with the position of the end of the drum/neck mounting piece (up & down -- 
while keeping things centered horizontally) until the distance from the top of the 12th 
fret to the bottom of the strings (I use the middle stirng) is about 4 millimeters. 
With any luck, this will give you a bridge heigth or somewhere around 20 mm or a bit 
less. When you have things just where you want them, carefully install the stout 
wood-screw to cinch things in place. If you cut the rectangular hole so the drum/neck 
mounting piece pits through tightly, no fastening or glue is needed other than the 
single end screw.

You'll also notice a bit of an unconventional 5th string "nut". Instead of a small
slotted screw, I wanted to move the string a small bit away from the four main
playing strings so the latter wouldn't be as "crowded". Worked nicely. The "nut"
is fashioned from a very small eye-hook that I cut & then bent into an "L" shape.  
A groove filed (& smoothed) on the top part of the upside-down "L" is where
the 5th string rides over. Drill the pilot-hole for the modified screw-eye a
bit smaller than usual so the "L" retains it's position & doesn't rotate.
Don't make this pilot-hole too much smaller lest the wood split. Experiment 
on a piece of scrap hardwood.

If you follow my neck-angle and other recommendations, a standard off-the-shelf 
banjo bridge should work fine on this instrument. Alternatively, a simple bridge 
can be hacked out of a scrap of wood in minutes that will work fine.   

Not needed! Simply drill five holes, each spaced 12.5 mm apart, low through the
metal rim 180 degrees opposite the center line of the neck. Be careful not to
hit the drum-head when drilling these holes. De-burr these holes on both sides 
to keep from cutting the strings. The distance between the 1st and the 
5th string (at the bridge) as measures 49 mm.

The distance between the 1st and 4th string at the nut measures 30 mm.

This article is still very much a work-in-progress. Check back for additional
information, fixed typos & mistakes etc.

Let me know if you build one -- LOT of fun for very little effort & expense..

Dennis Havlena - W8MI
northern Michigan

PS: When I refer to "right side" or "Left side" of the instrument, I mean right 
or left as shown in the photos.
Apologies for mixing up metric with non-metric measurements. In general I 
dislike the metric system but begrudgingly acknowledge it's usefulness in 
certain situations.

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