HOW TO CONVERT A GUITAR INTO AN OCTAVE-MANDOLIN.

Several years ago I was given a fairly inexpensive semi-acoustic 
electric guitar. Being that I don't play electric guitar, I 
converted it, in a few hours, into a long-necked, octave mandolin, 
for the price of two new tuning-machines, strings and some small 
hardwood scraps.

The resultant instrument is wonderfully rich in sound/tone and 
volume & is a whale of a lot cheaper than ready-made octave 
mandolins.

This conversion is so easily accomplished that it can be described 
quite quickly and easily.


               ADDING TWO ADDITIONAL TUNING GEARS
               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Elderly Instruments (& many others) sell inexpensive (less than 
$10 per set) guitar or mandolin tuning machines (aka tuning 
gears). I simply bought a set, hacksawed them into individual 
units, drilled the proper mounting holes at the head-end of the of 
the tuning box (there always seems to be room here to squeeze in 
another couple of tuners) & slapped em on. My two new tuners jut 
out at about a 45 degree angle, but this is of no consequence.


              //    _ _ _ _     \\
            //\   /         \   /\\  <-- the 2 new tuning machines
           ''  \/             \/  ''
              /   O         O   \
             |                   |
         ,,  |                   |  ,,
         ||--|  O             O  |--||
         ''  |                   |  ''
             |                   |
         ,,  |                   |  ,,
         ||--|  O             O  |--||
         ''  |                   |  ''
             |                   |
         ,,  |                   |  ,,
         ||--|  O             O  |--||
         ''   \                 /   ''
                \ ___________ / 
                 ||| || || |||  <-- the new 8 string nut
                 |~~~~~~~~~~~|
                 |           |
                 |           |   



                              NUT
                              ~~~
Remove the existing 6 string nut. Use it's shape as a pattern to 
whittle/file out a new hardwood nut. Carefully plot out and cut-in 
the grooves for 8 strings. Make sure the 2 strings nearest the 
edges of the neck are not TOO close to these edges. It seemed to 
work out niceley here that each of the strings within the 4 pairs 
should be about 1/8" apart. If in doubt, initially just make very 
slight grooves & only deepen them once you're satisfied with the 
spacing.


                           TAILPIECE
                           ~~~~~~~~~
The electric guitar I used utilized a conventional metal "fasten 
to the end of the guitar-body" type tailpiece. No conversion was 
made to it -- I simply (& quite effectively) hooked the ends of 
the two new strings through the existing string-holes. One was a 
bit tight with two strings now going thru it, and I probably 
should have drilled the mounting hole out a bit.
 
                             BRIDGE
                             ~~~~~~
This guitar had a "set-on" type bridge. I fashioned a new 
similarily shaped bridge out of rock maple and notched it for the 
four pairs of strings. This has worked out quite satisfactorily. 
Such a bridge need not be "streamlined" or fancy. Calculate it so 
that the grooves in the bridge allow the two outer strings to run 
down the neck about the same distance from the neck-edge along 
their lengths. Once again, initially make only very light grooves 
here & deepen them once you're satisfied with the spacing.


WHAT TO DO IF YOUR BRIDGE IS THE "THROUGH THE BODY" 
TYPE WITH NO TAILPIECE:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Remove the bridge saddle & ether a) add new grooves for 4 string 
pairs or b) Make a new 8 string saddle out of plexiglass or some 
other hard material. The two additional strings can be secured 
through the High E and low E bridge holes (this may necessitate 
"grooving" the associated mounting pins a bit deeper to take into 
account the fact that there now are TWO strings going thru each 
hole).

 
Now just string it up, adjust the action & play it! On the several 
instruments so converted here, I have had no sign that the 
additional pressure of two extra strings caused any problems. The 
former electric guitar, for instance, stays in tune from year to 
year - hanging most of the time on the wall!

I used appropriate gauge individual guitar strings, although they 
do sell octave-mandolin (or Cittern) strings in several catalogs.

Over the years I've converted lots of instruments from one thing 
into another and must say that this guitar - octave mandolin 
conversion ranks about the most successful ---- very easy to do 
too.
.................................................................
Late note (August 2002): Derek Darling had this neat idea, 
although not claiming it to be an original idea:
"I took a 12-string guitar and used it for an octave mandolin.

1. Remove the low E and the G string(s)
2. Move the remaining high strings (E and B) over to the next set
   of spaces.
3. Retune the A string to G, the D string stays the same, the old
   B string down to A, and the new E (high) string stays the same

Viola, now you have an octave mandolin. Another variation is to
have all the strings in unison, more of a Bouzouki sound.
..................................................................

Dennis Havlena - W8MI
Straits of Mackinac
northern Michigan 

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