Long Time Ago
For us, each instrument that comes through the door is rewarding to work on. Many have great sentimental value, most are technically challenging, and some have deep historical significance. When an instrument has all three of these qualities, the repair process is always fulfilling.
A beautiful, old parlor guitar was brought in—the neck cracked at the heel, the dovetail broken in half and the top splintered. The customer wanted to know if it could be made presentable and, hopefully, playable again. The guitar had been handed down in his wife’s family for four generations, and was given to him as a wedding gift. Unfortunately, he sat on it.
During the initial assessment, we looked for an indication of who made the instrument and when it was made. There were many well-made parlor guitars put out in the late 19th to early 20th century, and many had only minor markings. On this example, we found a clear makers stamp in the sound hole — “H. A. Schatz, Boston.”
The “ice cream cone” heel, fine quality woods, faded rosette veneer colors, aged finish and general look immediately implied the instrument was at least 100 years old. These characteristics are also very reminiscent of an old Martin guitar.
Upon research, we found that Heinrich Schatz (called Henry in the United States) was a friend of C.F. Martin’s in Germany and worked with him in the US in the 1830s. Between 1845-1850 he was building guitars under his own name in Boston.
The maple neck snapped with half of the heel and dovetail left in the body. A large section of the top reaching to the sound hole also snapped off but remained glued to the fingerboard extension. A small baggie of soundboard chips had also been saved.
After carefully removing the top piece from the fingerboard extension, the broken heel piece was removed from the body and glued back on to the neck.
We wanted to reinforce this joint with an invisible spline. First the heelcap was removed and a series of holes were drilled into the heel. A small scrap of Schatz’s original paper shim is visible on the bottom of the dovetail. He used a scrap of heavier stock paper with German Blackletter printing.
The wood around the holes was cleared with a vibrating saw to make a channel and finally, the slot was cleaned up with chisels, files and sanding blocks. The slot went to just inside the outer profile of the neck. 
A 7-layer piece of plywood was fitted to the plane of the fingerboard and the back of the slot and was glued in. All gluing procedures were done with hot hide glue.
The spline is pared to the original profile and the broken pieces of the dovetail remade. The visible crack was filled with tinted shellac and the heelcap glued back on. Time to work on the body!
Not a pretty picture. The long left side crack was there before the current mishap and is outside of the fingerboard extension footprint. The right side crack luckily is under the fingerboard. Many hours went into solving the jigsaw puzzle of reassembly. Pieces had cracked and splintered in over-and-under ways so that there was an exact reassembly order that had to be followed. Hide glue sets very quickly so every maneuver was tested and practiced without glue first.
After a number of small rosette and sound hole chips had been re-glued, the main soundboard piece went back in. With the body and neck made whole, the dovetail fit and neck angle were checked. Turns out it needed a neck reset. Here’s a dovetail shim is being glued on.The neck is glued on and the guitar is strung up to pitch! You can see the rock solid, refinished ice cream cone heel.
http://youtu.be/dfDaZ1MHGSAA little noodling to prove it works and it sounds very sweet! As a final note, I highly recommend the book Inventing the American Guitar, The Pre-Civil War Innovations of C.F. Martin and His Contemporaries for a scholarly and highly illuminating history of the German instrument guilds, C.F. Martin, Madame de Goni, James Ashborn and other long ago innovators that set the course for the acoustic guitars we play today.