DIY Network

Handmade Mandolin, Part 1: Red-Spruce Top From "Handmade Music" episode DHMM-105

	Like the acoustic guitars made before World War II, classic mandolins have tops made from prized red-spruce wood.
	The "Holy Grail" of mandolins -- an original Gibson F5.

The quest to build the perfect mandolin mandolin leads DIY's Handmade Music to the Ryman Auditorium in Nashville, Tennessee. It was from the Ryman's stage that a man named Bill Monroe introduced the world to bluegrass music. That was 1945 and it was an F5 style mandolin that delivered the unique sound that has become so familiar to fans of bluegrass and traditional American music. Since that first introduction, the world hasn't stopped tapping its toe to that high lonesome sound, and musicians haven't stopped trying to replicate Mr. Monroe's style. But 1920s-era Gibson F5s are hard to come by, and that's where Lynn Dudenbostel comes in. Lynn is a craftsman who replicates the look and sound of vintage mandolins like those built by the masters during the golden era of guitars and mandolins. In the first of three episodes devoted to the mandolin, we learn why the instrument is special and witness the first steps in the process of building one from scratch.

In this first segment, we begin with the construction of a red-spruce top. The top features a set of tone bars on the inside of the mandolin and Lynn shows why this step is referred to as "giving the instrument voice". Old-school gives way to high-tech when Lynn introduces the use of a computerized router to carve the top and the curly maple back.

In later segments, Lynn prepares the back and sides of the instrument from curly maple, and viewers get a taste of how Dudenbostel mandolins sound when pushed with a virtuoso performance. Andy Leftwich and his fellow Kentucky Thunder band-mates put a Dudenbostel mandolin through its paces in a bluegrass jam.

Materials:

Red-spruce stock
CNC (computer-driven) router
Jointer
Drum sander (thickness sander)
Hot hide glue
Gluing fixture
Carpenter's pencil
Safety glasses or goggles

Safety Alert: Always wear safety goggles or safety glasses when
working with wood, power-tools, saws, drills, routers, etc.

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Figure A

Red-Spruce Mandolin Top

Master luthier Lynn Dudenbostel builds stringed instruments by hand, in the style of masters who made the great instruments in earlier decades. He built his reputation predominantly by replicating a specific classic instrument -- the Gibson F5 mandolin. "1922 through 1924 was considered the golden era for Gibson mandolins," says Dudenbostel, "and Lloyd Loar was the acoustic engineer at Gibson during that time, and those are the most sought-after mandolins." In fact, some of Loar's original hand-written documentation has been located which specifies the Virginia Adirondack spruce (a.k.a., the red spruce) as the wood of choice for the instrument's top. So the objective for this Handmade Music series is to build a classic F-5 style mandolin using a top made from red spruce just as acoustic engineer Lloyd Loar would have wanted.

• In selecting red-spruce stock for building a mandolin, Dudenbostel looks for evenness of grain, good definition between the winter and summer growth in the wood (seen in cross-section, like the familiar rings of a cut tree) and a ringing tap tone (as opposed to a dull "thud") when the piece of wood is lightly struck (figure A).
  
  
• Once the wood has been selected and cut to size, two pieces jointed for creation of the top. Typically, two book-matched pieces of spruce (figure B) are joined together by their jointed faces to create the single top-piece.

  Once the joining surfaces have been jointed smooth, they are glued together using hot hide glue and a gluing fixture. Hide glue is made from ground animal hides and is ideally suited for soft-wood applications.

  To process the wood to make it ready for carving, one side -- which will eventually be the bottom surface of the top piece -- must be made perfectly flat. The face that will eventually be the top begins as a wedge shape. To flatten the bottom surface, the glued pieces are passed through the thickness sander. Two temporary rails balance the wedge shape as it passes through the sander (figure C).

  Figure B

  Figure C

  
  
  The planed piece is left fairly thick as the extra thickness is needed for the arch-top style of the Gibson F5. Rather than bending thin stock to shape, Lynn creates the arch by carving the shape from thicker stock. A template is used to mark the outline of the top onto the stock (figure D).

  Carving the thick top was once a process that had to be done by hand, but Lynn makes use of some modern technology for this phase of the mandolin's construction. After the book-matched pair has been glued and sanded flat on one surface, the stock is then placed on a CNC machine to do the rough carving (figure E).

  Figure D

  Figure E

  
  

  Figure F

  CNC stands for computer numerical control, and the CNC machine is actually a router that is driven by a computer. In Lynn's case, the mandolin's top will be finished by hand, but he does use the CNC router to rough-carve the basic shape. Later, he Lynn will do the final carving, graduation and "voicing" of the instrument by hand. Rough-carving begins with the top's inner surface as surplus wood is dished out (figure F). The top is then flipped over to expose the outer surface. Once the computer has completed its program, the basic shape of the mandolin top is visible. This CNC process takes slightly less than 2 hours.
  
  

In the segment that follows, Lynn does just that. He hand-shapes the top and back.

RESOURCES :

Stewart MacDonald's Luthier Supply Shop
Website: www.stewmac.com

Luthier's Mercantile International, Inc.
Website: www.lmii.com

Pioneer Valley Luthier Supply Company
Website: www.pioneervalleyluthier.com

GUESTS :

Lynn Dudenbostel, Luthier
Dudenbostel Stringed Instruments
Knoxville, TN