Factory Cello - Broken Neck

 This cello came to me a few years after the owner's old girlfriend caught it with a Tae Kwon Do kick.  An expensive instrument would warrant a new neck being carved and fitted, in this case the cost of replacement would greatly exceed the value of the instrument.  So, a planned glue repair is in order.

The first step was to remove the fingerboard, and  to make a simple bond repair using high-strength epoxy.  Hide glue was not appropriate, as it is too weak and there is no intention of ever dismantling the repair.

The join was then reinforced with two long dowel pegs.  One was vertical, the other inclined towards the neck.  Once the cello is restrung, the principal tensile forces would pull the neck upwards, so be leaning the dowel the peg will experience compressive tension, with minimal flexion.

Before gluing the pegs I cut a V along each rod, to give excess glue an escape route.  Otherwise the glue would pool in the bottom of the hole and stop the dowel from penetrating to its full length, thereby weakening the joint.  The glue used was regular PVA wood glue.

Once the glue was set, I cut and smoothed off the proud peg ends, and reinstated the fingerboard.

There were also a couple of face chips along the neck join, so I rebuilt those with some matched spruce.

The varnish finish (factory spray stain and spray nitro) had been damaged around the repair, so I worked a combination of oil stains and shellac to restore the finished, before final polish and waxing.

Cut and set a new sound post, refit the spike button ad restrung.

Ready to play!

Hofner Classical Guitar

 This came to me from a local high school.  The head-stock had been snapped off.

The repair had three main stages.

First, the broken ends were glued together with high-strength epoxy.

Sometime between the damage occurring and he guitar being assigned to my care, a piece of the neck timber had vanished.  

I needed to reinforce the join, so I cut a diamond-shaped block of Casuarina wood, and glued it into a matched recess that I cut into the rear of the neck.  

The block position crossed the join, filled the gap from the missing wood and gave strength at a major flexion point.

A few days later, I trimmed the excess wood and smoothed the surface.

New nylon strings, and started the cycle of string tuning and re-tuning as the strings stretched to their final length.

Epiphone Les Paul

 This came to me from the music department of a local high school.  The head had been snapped off.

The repair began with some strong epoxy glue to reattach the head along the break.

A simple glued join would not be strong enough.  The Les Paul, being an electric, has a truss road, so I was unable to inset a single central block to reinforce the break, so I cut two slices of ebony off an old violin fingerboard.

Using a cutting disc on my rotary tool, I cut two slots along the neck, crossing the break.  I then set the ebony slices into the slots.  

Trimmed and smoothed, the repair was done, but the finish was a mess.  A couple of applications of red wood dye, and a few coats of spray lacquer followed by cut-polish cream and wax, and the neck repair was complete.

The guitar also needed a new machine head (top E) and some new pot knobs.  Once strung with light-gauge strings, so as to minimise the tension on the neck, I found that one pick-up was silent.  A thorough trace and test through the whole wiring harness found the poor contact, which was soon repaired.

Restrung, and set the action and intonation, and the guitar is ready for more performances - more Fripp and less Townshend, though!

Gibson SG

 (Chinese) Gibson SG Clone

The owner brought this to me new from the factory.  It had a maroon-ish paint finish, and he had a replica 1960's pick-guard that he wanted fitted.  To fit the guard I needed to move the neck pickup, bridge and pickup selector switch all backwards a few mm.  And replace the paint with a traditional red mahogany finish.

First mission was to remove the paint.  Sand, sand, scrape, sand again.  Removing the colour was not enough, as the factory had used a clear poly base coat to soak into the timber and provide an even surface for the colour layers.  The palm sander was good for the flat surfaces, but the details were manual.  Twelve hours and much toxic dust - if COVID was good for nothing else, it left me with a good supply of breathing masks!

The construction of the guitar was revealed once the paint was gone.  Five wooden blocks were glued together length-wise, with a flat sheet on both front and back.  The joins were quite distinct around the beveled edges.

Next was the repositioning of the hardware.  In this image, just behind the bridge foot is visible the wooden plug of the original mount hole. Also visible is my mark-up line for the pickup.

The finishing was progressive - a red wood dye (two coats), followed by walnut oil - two dilute coats, two solid coats. Wet sand (600 grit), two more coats, wet sand again.  Then Rustoleum clear lacquer - three coats, wet sand 400 grit, one coat, wet sand 600 grit, two coats.  Polish, and then wax.

Check the electrics (resolder a loose earth!), install pickups into the pickup guard, position and tighten everything in place. Mount the strap studs, machine heads, string and set up.

This was done by first setting the bridge saddles to a zero position. Each string: tune open, and check 5th fret note. Adjust saddle and bridge height (action) to bring the intonation into true, so that both open and 5th fret notes are accurate. Confirm using a pinch harmonic on the 12th fret.

With the intonation set, set the pickup heights to give even sound across all strings.

And, done.

Heirloom Restoration

This heirloom was given to the owner's father as a boy, when the prior owner was killed in WWI. He grew and played professionally until his retirement, and his daughter now wants it repaired for her grandchildren...
There was a long split in the face, with a second crack alongside the bass bar. An edge of a waist had been eroded, as well. Also, there was a lot of mold in the face varnish, which had also been totally worn away in some spots.

A thorough clean inside, matched spruce grafted in along the edge waist with some new purfling, splits glued and cleated, and new finish to match the body.

Strung with a matched set from the instrument's own case, and it sounds wonderful - a true soloist's instrument.

Rogue's Gallery

 Over the years my workbench has hosted many instruments that have been damaged in ways that should not have happened.  Here are a few of them:

1.     Violin bridge - hot-glued to the instrument:

2.    Double Bass - a neck repaired with two screws and a bolt:

3.    Markneukirchen Violin (Late 19th Century catalogue instrument) - the inside of the face could never be seen, so why go to the effort?  Rough gouging with what passes as a bass bar carved out.  Pictures are before and after I finished the job, 100 years later:

4.   Scissors wielded by child - pointy end into an 1877 violin.  I glued the pieces together, and then fitted a cross-grain filet into a shaped recess behind the face.

Violin f-Crack

 February 2025

This is an heirloom instrument of some value.

Made in (estimated) the 1890's for the German trade, it is a classic Maggini copy (extra turn in the scroll, double purfling) from an extraordinarily highly-flamed maple, with the neck likely carved from the same timber.

There had been an earlier single-cleat repair on a long f-crack, but the single cleat had not kept the crack from opening again.

Removing the face showed the repair history, with a second (smaller) crack cleated alongside the major crack.

As replacing the cleat would not suffice, I cut a cross-grain filet from some larch that I had already sized (see my post about a dulcimer build!).  A sharp pencil outlined the filet when placed over the crack, and some careful work with a scalpel and carving chisel soon excavated a light recess in the violin face.

Some fresh hide glue was used on both surfaces, and the filet was then clamped in place for a few days for the glue to properly cure and set.

The glued filet was then dressed down to a shallow curved profile that was lower than the original cleat.  By cross-graining it the filet gives a greater structural strength to the face along the crack without sacrificing tone.

I then reinstated the face, and late completed the normal set-up (soundpost, check-ream the peg holes, lubricate the pegs, restring).  The chin-rest was a little tired, so some linseed oil rejuvenated it nicely.

Result?  The violin has a tone worthy of a soloist's instrument, with a warm rounded sound, no treble squawk, and precision of pitch and clear projection.  Ready for another century of playing!