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| Shipping a guitar can be
dangerous business if the guitar is not prepared properly for it's
journey. This guitar was broken in shipping due to rough handling,
but also likely due to two packaging factors...the string tension was
not loosened on the guitar AND there was no padding added beneath the
heel to support the heel/neck block area inside the case. Many
commercial cases (even high quality examples) have a string box neck
support that is tall enough that the back of the guitar (at the heel) is
actually raised off the back of the case. This gap causes that
area of the guitar to be vulnerable to damage if the box is dropped or
significantly jolted during transit. Because the butt end of the
guitar is firm in the bottom of the case, and the neck is supported with
the gap behind the heel, the heel and block area take all the stress of
such a shock. |
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This guitar, a 1968 Martin D-35, was
damaged in just that manner during shipping. The shock of
being dropped was focused on the joint area and the heel, dovetail
block and sides cracked dramatically. The cracks in the sides
went about 9"-10" down the shoulders and to the waist from the heel.
The cracks were very clean, with little or no splintering of the
rosewood and very little finish loss along the edges. The heel and
dovetail block breaks were very clean as well, with little or no
splinter or wood loss. But the dovetail block was broken completely
through to the inside. The fact that the breaks were clean added to
the optimistic outlook for the repair of the guitar. |
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The repair could be approached one of two
ways. The neck could be removed and the block and heel
repaired separately and rejoined. However, the open break in
the dovetail block creates the difficult problem of how to contain
the steam that is usually used to soften the glue in a neck joint.
Without a closed joint the steam goes everywhere and is ineffective.
Also, it appeared that the neck angle on the guitar was fine, so
removing the neck was not judged the best option. The second
possible approach is to reglue the heel and dovetail block in one
operation without dis-assembly, and tackle the side cracks after
fixing the block and heel. It is this second approach that was
used. The first challenge is how best
to get the glue into the broken block and heel and spread it
sufficiently. I chose regular Titebond for this operation.
As shown in the photo, I used a turnbuckle type brace jack to apply
outward pressure on the top and back just next to the block in order
to open the break and hold it open. A small amount of pressure
was all that was necessary to accomplish this, and too much pressure
would have stressed the already broken sides and possibly cause more
breakage. With the jack in place the crack was held open
enough to allow room to work glue into the gap. I used a very
thin and small spatula to spread glue deep into the joint. At
this time, only the block and heel were being glued, the sides were
left unglued to be addressed later. |
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Once I was satisfied that there was sufficient
glue in the crack, the jack was removed, the heel clamped and left
to dry. Since the block had been broken completely through I
checked for perfect alignment of the heel on the outside and the
block on the inside and made minor adjustments until the alignment
was correct. One clamp was just on the heel cap, one at the
edge of the body to apply pressure on the dovetail block and
dovetail of the neck, and one slightly inbound to clamp the inner
aspect of the dovetail block. As always, damp rags were on
hand to take care of any and all glue squeeze out both inside and
out. |
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Once the dovetail block was dry I was ready to
address the side cracks. Side cracks can be difficult to align
properly, especially when they extend from one curve to another on
the same guitar size. As you align the crack in one area, the
side can pucker or dimple slightly somewhere else on the crack
making it difficult to get an even surface along the length of the
crack. In addition, carpenter's glues like Titebond can cause
problems due to their tendency to make pieces "swim" against one
another under clamping pressure. For those reasons, I chose
the following approach to the side repairs.
Working from the inside with one hand and the
outside with the other, I manipulated the side cracks so that they
were level and aligned. I worked in small increments, pushing
a few inches at a time into alignment and then having my assistant
(my 15 year old son) apply a cam clamp to the area that had been
aligned. The clamps would hold that area in place while I
worked on the next few inches of the crack. This process was
repeated until the length of the crack was aligned and clamped
completely closed with no glue in the joint.
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With the cracks clamped into alignment, cyano
acrylic glue was used to glue the cracks. Cyano was chosen
because it is water thin and would wick into the closed cracks like
water, and because it cures in a few seconds. The water-thin
character of the glue also makes this operation very tricky, as any
excess glue that forms in a bead and runs on the surface will cause
major finish damage (cyano eats through lacquer very quickly).
To prevent this, the glue was applied using a micro fine pipette
with just the very tip filled with glue. A very small amount
of glue was applied along the crack seam and allowed to wick in.
Then the pipette tip was filled again and the process repeated until
the entire crack was glued. |
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As is true with many repairs, (and certainly
anything involving finish work) much labor is expended in doing
cosmetic work. With the cracks glued and stable, the next job
is to make the finish seam as inconspicuous as possible both on the
sides and the heel. Lacquer was touched in using a brush on
the sides and the heel. I used rather thinned out lacquer
until I could see that the lacquer seam was filled. Then I
switched to a slightly thicker lacquer to build up a small amount
that then could be sanded back flush, leaving an unbroken surface.
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After the lacquer touch in is finished and the
final level sanding done the repair is done. The crack
virtually disappears on the sides, little or no evidence exists that
the damage ever happened. On the heel, the only evidence is a
very slightly visible seam line where the crack was repaired.
These pictures were taken several weeks after the lacquer touch in,
when the lacquer had cured and had some chance to "sink in" to the
repair (as is a characteristic of lacquer). Subsequent
additional applications of lacquer to the area with some light
sanding would likely make the seam disappear entirely as a surface
issue. |
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