Custom OM Guitar #49 153

Completed September, 2015

(click any of the thumbnails for a higher-resolution photo)

This custom guitar is dressed up with gorgeous cocobolo back and sides and a tight-grained red spruce top. Waverly tuners, a slotted headstock, and some custom inlay completes the package. This instrument is light as a feather, and the tone is crisp and balanced and full bodied. In a word, sweet. This is a custom build for a Virginia customer who bought his first Skipper guitar through Gruhn's in Nashville.

Here's just a small part of his evaluation of the new instrument:

Overall sustain is stunning. I would expect this of an older, fine guitar, but nothing this young has this mature sustain.

For more excerpts of this review, visit our Testimonials page.

Construction Photos

The very first step in this custom build is a finalization of specs and choice of materials. Here the future owner of his second Skipper guitar sorts through red spruce tops in search of that perfect one. The top and back plates are edged and glued together with hot hide glue. Cocobolo is an oily wood, so all joints are washed with acetone before gluing. The sides are roughly cut to shape on a bandsaw, then perfected with a small plane.

The sides are sanded to finished thickness. An adjustable external form is set to OM size, and an adjustable bending jig is set to match the waist profile. The sides are lightly wetted and wrapped in Kraft paper. A stainless steel, wood, and heat blanket sandwich is made, and the sides are bent to shape.

The sides are fitted into the external form and left to dry and cool. A head block is fabricated and glued together with hot hide glue. The head and tail blocks are glued to the sides. The back is sanded to finished thickness and cut to shape. Since this has just been introduced to my shop -- a very dry environment -- I'll let it hang in the open air for a few days to reach equilibrium before I glue in the bracing. Beautiful wood, wouldn't you agree?

A guideline for the rosette is laid out by eye onto the top. A center hole is drilled, and a channel for the abalone rosette is routed with a Dremel jig. A two-headed cutter cuts both inside and outside radii in one pass. A simple slot at the edge of my workboard allows me to "spoke" the ends for a good match. The abalone is glued into the recess with super glue.

A hand-ground fly cutter cuts a perfectly sized slot for the purfling rings, again gauged by eye to keep spacing equal. The purfling is glued into the slots with hot hide glue. The top is sanded to finished thickness, and the soundhole is cut out. Side reinforcing strips are glued in place. Vintage Martin guitars had fabric tape, which made gluing in the kerfed linings easy but did nothing to stop side cracks. Later -- and most -- manufacturers fit these strips between the linings, which led to cracks along the joint between the lining and the reinforcing strips. My reinforcements are both full length and flexible, like the vintage Martin tape, but are substantial enough to circumvent side cracks. Bracing stock is roughed out from straight-grained red spruce.

Mahogany strips are ripped to make kerfed lining. The strips are beveled on the drum sander, then kerfed using a sliding jig on the bandsaw. Short pieces of lining are first glued on top of the side reinforcing strips, then the balance of the lining is fitted between these pieces. The maple bridge plate is fashioned and glued into place.

A drum sander jig facilitates the arching of the back and top braces. The back braces are partially shaped and glued into place. The x-braces are also partially shaped, fitted together, notched to receive the bridge plate, and glued into place. Hot hide glue is used on all joints, and all cocobolo joints are washed with acetone before gluing. The short pieces of lining glued over the side reinforcing strips are pared even with the rest to result in an enduring system of side reinforcement and kerfed lining. The top lining is installed in the same fashion.

The balance of the top bracing is partially shaped and glued into place. Center-seam reinforcing is glued between the back bracing. A recess is cut for the end graft, and a celluloid graft and black/white purfling is glued into place. The sides are braced within the form, and the edges are sanded to match the top and back arching.

The braces are shaved, and I'm tapping as I whittle, listening for a multitude of musical notes with no dead spots, and for resonance and strong harmonics. When the top is tuned to my satisfaction, I trim the back braces in a similar manner. The bracing is notched into the sides and lining, and hot hide glue is spread on all mating surfaces and allowed to dry. The back is clamped to the ribs, and the hide glue is reactivated with a burst of hot steam.

The process is repeated with the top. Smaller pieces of cocobolo are bookmatched for the headstock overlay. The body is removed from the external form, and the overhanging edges are trimmed on the router table. An orbital sander is used to reduce the thickness of the top around the perimeter; this "loosens" the top for better resonance without threatening the structural integrity. Binding and purfling recesses are routed.

Since the side purflings tend to twist, they're prebent before gluing into place. Top and backl purflings are glued in, followed by the celluloid binding. The binding is held with tape, then "roped" with cloth strips. Since the adhesive I use swells the bindings, the body is set aside for a week or two to allow all the volatiles to escape. The neck blank is cut roughly to shape. The truss rod slot is cut, and matching slots in both neck and fretboard are cut to receive the full-length carbon fiber reinforcing bars.

A specialized jig cuts perfectly matched and aligned dovetails in neck and body. The neck is left just a tiny bit proud of the body, and final fitting is done by "flossing" with strips of sandpaper. The neck heel is tapered before the final fitting.

The recesses for neck reinforcing are filled in the area under the headstock. The headstock overlay is sanded to finished thickness and glued to the neck. The neck and headstock are cut roughly to shape, and pilot holes are drilled for the peghead slots. A template is affixed to the back of the peghead with two-sided tape. The exterior shape is defined on the router table. A jig assures correct spacing for the tuning posts.

This project is getting large, so I'll continue it on a second page.

Go to Page 2 of this project

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