MARK'S GUITAR, PART 2

If you skipped part 1you'll not know how Mark's guitar got this far.  If you've seen it, or if you like coming in during the middle of the movie, cool, let's go:

The edges of the top and bottom were zipped clean using a router equipped with a flush trim bit.  The sides are scribbled with white pencil, then dressed flat and clean on the belt sander using a 60-grit belt.  Yup, it takes a sensitive touch, but it's fast.  The waist and the cutaway will be cleaned up by hand.	A corner graft of matching wood is added.  The groove is cut with a dedicated router, the oversized graft is super-glued in place, then the graft is worked down with sanding blocks.
This is the binding router.  The fixtures were made up by a machine shop.  The aluminum plates (feet) hanging above the router are interchanged to adjust the width of the binding cut.  The roller bearings are swapped to adjust the thickness of the binding cut.	Here's a close up.  Notice that in the pix above there is already a binding ledge cut on the guitar.  This is a hogging cut of small dimension made so that the thickness of the sides can be gauged as they are dressed down.  The guitar is placed side-down on the roller bearings and gently rolled around until the cut is complete.  Two or 3 trips are usually made to assure a uniform rout.

The butt joint is seldom perfect, and doesn't need to be.  A graft will be fitted as part of the binding routine.  The maple graft and black/white/black purfling lines will later be mitered into the purfling of the binding.
	This jig and dedicated router are used to cut the tapered slot for the butt graft.
The graft has been installed and the ends trimmed to length with the binding router using a different foot than for binding.  The red-dyed bit is a binding sample used to fit the ends of the graft to the binding-to-be. . .

. . .like this.

The curly maple binding has to be bent in the same manner as the sides.  H&D has a holding form for the  normal OM binding, but none for the cutaway side yet.  So to maintain its shape the cutaway binding was temporarily taped to the guitar.
	The ends of the binding have to be fitted to the end graft, then the glue work can proceed.  Multi-piece binding can be frustrating.  Mark's guitar wasn't too bad, with only three pieces of purfling to a side.  There's two strips of .045" wide black/white/black.  In the middle is a flexible strip of polyethylene.  Glue won't stick to the poly.  The poly is about .047" wide, the same as the abalone that will replace it after the glue has dried and the poly is pulled out.  As you can see, the maple binding is installed at the same time.
	Binding starts at the butt graft and finishes at the corner of the cutaway.  On a noncutaway the binding would end at the top centerline.
The binding/purfling stands proud of the top and must be scraped to the level of the poly strip.  If it doesn't get too abused the poly is good for 4 or 5 jobs.  Once the glue squeeze-out is removed it pulls free pretty willingly.

	Abalone trim retails for almost $1 per inch.  Thank you Jeff Huss for getting it for me wholesale.  Aba-lam is abalone plywood (so to speak).  Micro sheets of abalone are glued into usable sheets that are then cut into strips (if desired).  Aba-lam is prettier, cheaper, and easier to use than solid shell but harder to cut with a jewelers saw.  Its not as good for fingerboard inlays, either, 'cause you may lose the color matching you want as the layers are sanded through when the inlays are dressed level.
	The abalone is pressed into the groove left by the poly strip.  Carefully breaking it is the only way to get it to go around bends.  This part of the job is usually a lot of fun.

Front view, body finished and sanded to 220 grit.	Back view, finished and sanded body.
	I couldn't resist a closer shot of the back.  We'll see the body some more when the neck is fitted, but it won't look this clean again until its sanded to 320 grit just before the finish work commences.

Before we can build the neck we have to get the body ready to receive it.  It's a simple matter using the H&D jigs.

	A simple drill guide jig using hardened bushings is used to drill the holes for the alignment pins.  These are temporary pins made of Delrin.  When the guitar is finally assembled steel roll pins will be used.
This is the same sort of jig used to drill the pin holes.  This jig is slipped over the delrin pins and a 1/4" drill is used to drill the holes for the bolts that will hold the neck to the body.
	This is a secret tool that was made up by a machine shop.  The cutting bit was cut off a Forstner bit, reversed, and welded back on.  The cylinder above the bit is a bearing-mounted depth stop.  In use this tool is inserted through the soundhole and the shaft is stuck out through the bolt holes and chucked up in a hand drill.  The drill is run in reverse and the bit is pulled against the head block.  The purpose is to cut the countersinks for the bolts and their washers.
A simple plywood jig is used to rout the truss rod slot in the body.  The rod adjustment nut will protrude just beyond the head block.  OK, the body is prepped for the neck.
	Here's the stock for five necks.  Small blocks will be cut off the build up the heel and the headstock will be cut off at a 15-degree angle and glued back on.  You'll see.  This is the only way I've ever made acoustic guitar necks.  H&D only uses 1-piece necks, but there is a whole lot of waste.  Some people frown upon built-up necks because the glue lines often show, but I've always believed that good joinery should be celebrated and not disguised.
Guitar making is full of jigs, a lot of them just this simple.  The 15-degree angle fence has a runner in the miter slot of the table.  The result is a clean decapitation of the headstock.

	Here you can see how the decapitated portion is glued back on to form stock for the headstock.  Three necks have been so prepped.
The headstock has to be 3/4" thick for the slotted headstock Mark wanted.  Most of the excess is zipped off on the bandsaw, and the remainder is dressed to 5/8" thick with this belt sander jig.  Note that the heel block has also been glued on.
	A veneer of Brazilian rosewood brings the headstock back up to 3/4" thick.
Before the slots can be cut the headstock has to be routed for binding and the binding-purfling installed.  Polyethylene filler is used for the purfling, just as with the body.  When the glue has set the poly will be pulled and abalone strips put in its place.  You can just see a bit of truss rod slot above the headstock.  I should have mentioned that the slot was cut on the table saw before neck construction was begun.
	This drilling guide is used to make the holes for the tuner shafts.  The layout line on the headstock is matched to a line scribed on the plexiglass part of the jig.  The jig used to cut the slots in the peghead indexes off the middle tuner hole.  If you're sharp you've realized that this isn't Mark's neck.
Here's the slotting jig.  A rub guide is mounted on the router.  The bit is plunged through the guide and into the wood.  At least three passes are necessary to get a clean cut.
	Here's the finished (but unsanded) headstock  The string ramps were cut with a rattail rasp.  Note that the fingerboard is glued on, too.  Construction has to proceed in a given order, but photography doesn't
This is back in my shop.  The fingerboard is being trimmed to size on the table saw.  A runner beneath the platform of the jig slides in the miter slot of the saw table.  The platform was run through the table after the runner was in place, so anything overhanging the edge of the platform gets zapped off.  Actually, Mark's board is being trimmed undersize, and the maple binding will bring it back to spec.  The fret slots were cut with another table saw jig long ago.  This board has been waiting for Mark for years.
	Half of the binding is being glued on using a tapered form that allows both sides to be glued up at once.
The angle of the neck has to be matched to the pitch of the top of the body, then adjusted for the height of the bridge.  The heel is cut at that angle at the location of the 14th fret of the fingerboard.  Here the cut has been made on the table saw and jigs have been used to drill the holes for the three steel index pins.  Threaded brass inserts have been placed in the heel to receive the bolts that will hold the neck to the body.  What you can't see is the maple dowel that has been inserted under the heel cap.  The inserts are threaded into the dowel rather than into the soft end grain of the mahogany.  The slot for the truss rod is also visible.

Though Mark's guitar was completed quite awhile ago, there were parts of its construction that I didn't catch on film.  It was more important to finish the guitar than to document it.  Look for Part 3, concerning neck shaping, inlay, and perhaps finish work.  It won't be Mark's guitar, but the processes will be the same.  Check back later

Many thanks to Jeff Huss and Mark Dalton for the use of the company shop after hours!

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