R ESTORING AN ORIGINAL
JOHN BROWN
1933 National Duolian Resonator
National built the Duolian metal-body vintage The tools and materials used for this restora-resonator from 1930 to 1938. What makes tion are available from stewmac.com or a
this Duolian different from many others is local hardware store:
its frosted Duco crinkle-type finish, in a very #5391 Shop Stand and Guitar Repair Vise
rare shade of grey to dark green. This feature #1816 Nut and Saddle Vise
makes the restoration that much more plea- #4167 Glue Brush
surable. It’ll be good to have this guitar fit for #4199 Mixing Cup
human hands to play again. #5174 Slow Setting Clear Epoxy
#3721 Small Cam Clamps
Extra Strength Stripper
Dental pick/Dental scraper tools
1933 Duolian Specs:
Steel Body with rolled-edge f-holes
Single convex 9. 5" diameter cone
Wooden maple biscuit and saddle
Nickel-plated tailpiece
Ebonized maple fingerboard with no binding
Fingerboard radius 10", gradually flattening to 15"
Total of 19 frets, 12 frets clear of the body
Mahogany round “C” neck
Slotted peghead stamped NATIONAL DUOLIAN
Headstock Rebuild
It was very important to remove all of the
epoxy from the previous repair so that I could
get a strong and proper fit, ensuring that the
wood would not come apart again.
Stamped on peghead top is:
C 666 0
MADE IN USA
PAT.1808756
OTHER PAT.PEND.
Diagnoses
Headstock
Clearly, the bass tuner side of the headstock
needs to be repaired. This will be the second
time. You can see it had previous epoxy slapped
on everywhere, which is finally weakening and
coming loose. I could tell by observing the gluing surface of both pieces that there was no
pressure applied in the gluing process to help
create a tighter, stronger glue joint. The glue
was applied kind of like thick frosting on a cake.
What seems to work best for removing weak
epoxy is extra-strength stripper, which I normally use for removing finishes. I carefully
apply the stripper with a glue brush until I can
see it begin to react. I use my smaller flexible
spatula with dental tools and gracefully shovel
out the old unwanted glue, but without alter-ing any of the wooden foundation, removing
one layer at a time. As you see in the picture
I’m securing the neck with my Shopstand and
Guitar Repair Vise. The Nut and Saddle Vise
works well for gripping and holding the smaller two pieces of wood while removing the old
glue. Note: keep a small cup of water and a
Q-tip near by, so that if the stripper goes in
an area where you had not planned, a quick
dab of water and wipe from the Q-tip on the
surface will deactivate the stripper.
Fingerboard
At the fingerboard extension there is a 9" crack
with a 1/16" wide gap. This area has never
had any previous repair done to it. It appears
that one of three screws used to secure the fingerboard to the metal body, hiding under the
upper last fingerboard dot, has caused or at
least encouraged the fingerboard to crack.
Body Corrosion
This instrument has been kept in a very
moist atmosphere for some time, and the
steel body will need some mild cleaning and
conditioning. Care must be taken to avoid
distorting the frosted Duco finish.
Now that all of the epoxy is removed we’re
ready to put the three pieces together and
check the fit. Overall, the fit is looking good,
considering that there are small to medium
slivers of missing wood. We’ll go back to
address those later, after the first stage of
gluing is completed.
We’re now ready to dry assemble using
clamps. It takes a few tries clamping up the
side wall of the headstock to get all three separate pieces to sit right for the final fit. I really
want to have this part down before mixing my
glue, slow-setting clear epoxy. I’m using a variety of non-stick 4-1/2" plastic clamping cauls
to tidy everything up.
We will be addressing final stages of the
headstock rebuild, fingerboard crack and
body corrosion in next month’s “Restoring
an Original.”
John Brown
John Brown, of Brown's Guitar Factory, is the inventor of the
Fretted/Less bass. He owns and operates a full guitar manu-
facturing and repair/restoration facility, which is staffed by
a team of talented luthiers. He is also the designer of guitar
making/repair tools and accessories that are used today by
instrument builders throughout the world.
brownsguitarfactory.com
info@brownsguitarfactory.com
