Neck and fingerboard
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Processing a mahogany plank for necks: Here's a primo slab of pattern-grade honduras mahogany: dead straight and dead-flat horizontal grain: perfect for creating a batch of ultra-high quality neck blanks. First I plan for 18" shafts, 7" headstocks and 3.5" heelblocks. It takes a little figuring on how to get a good yield with minimal waste. |
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Here's a neat trick: I'll reserve the lower, shorter portion for blocks, and the longer upper portion for headstocks and shafts. First, I'll two 15-degree slope bandsaw cuts in a strategic location. Then, I'll joint the sloped cuts smooth and true. IMPORTANT: take as much time as necessary at an early stage to insure that all your power tools are cutting scrupulously square: the bandsaw band square to its table not only side to side but vertically too; the jointer fence set up to joint perfectly square to its bed. You'll make up this time later by not having to dork around endlessly with surfaces that don't meet and seams that don't match up. |
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All the shaft and headstock elements are bandsawn to 3/4". The shafts will later be abrasive-planed to 5/8. Some may end up as thin as 9/16. The headstocks will be left at 3/4 for classic, some will later be reduced to 1/2-inch thickness for steel string. |
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By sawing the plank at 15-degrees, and jointing the angled face, my headstock scarf on all the elements are now virtually ready for gluing with little or no fussing around. |
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Here's my neck blank fixture. The long block is fixed, but the short block is screwed on one end only, so it can rotate to the angle of the headstock |
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Here's another view of the neck blank jig. |
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The idea is that you can align and clamp both elements to prevent them from sliding apart while you clamp the glued scarf joint. |
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Cauls are used every where to protect the workpiece from clamp marks and/or spread the clamping pressure over the entire glued seam. Three clamps placed vertically across the scarf seam is sufficient. Take care of c-clamp pressure. They throw far more pressure onto the seam than the sliding bar clamp. So crunch the bar clamp down but tighten the c-clamps moderately. |
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I don't locate the heel block till AFTER I clean up the headstock show-face in case the break-line creeps back in the process. The nut sits flat at the break (unlike Martins) and then I measure down to the 14-fret location of the selected scale length (I made up a little spreadsheet on my Clie that lists my fret measurements for any scale, plus all the crucial measurements for any scale). The final line is 1" further down for the neck tenon. |
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The last line is traced down the side and locates the rearmost face of the heelblock during gluing. |
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After cleaning and truing up the blank surfaces, I slot the centerline of the blank shaft with a 1/4" ball end milling bit to within .1 of the undersurface. I was going to make a truss rod, and show how, but I found out that Luthier's Mercantile is selling one similar to the one I make for twenty bucks. That's about what it costs me to make one, so I'll save me the headache of dealing with torches and thread taps (I'm not much of a metalworker anyway) and just buy them from now on. They require a 1/4" slot instead of the 3/16" slots I've been doing for years. I've also dispensed with the pinned mortise and tenon neck joint that I was using in 1985 when I wrote the book, and instead have gravitated towards a brass barrel-bolt system that I devised for myself that is simple and foolproof. In the photo above, I prepare the heelblock portion of the neck blank to accept the 10mm barrels for the barrel-bolt system. The bolts are ubiquitous--I can get even get them at my corner Aubuchon franchise hardware store. They have to be accurately located, and as I don't have a 10mm brad point bit, I use my 3/8 brad point bit first and follow with the slightly larger 10 mm conical-point tip. |
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I have to swing the drill press table all the way over to access the rear centerline of the heel block for the 5/16 drill bit that will accommodate the barrel-bolt bolt. The drill is oversize because the neck will be set at a slight angle to the soundbox's headblock, and the bolt would jam in a tighter hole otherwise. Here's another good reason why all the surfaces of all the elements of the neck blank, heelblock included, must be scrupulously square. |
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I used to table saw the tenon checks away from the blank, but a wide bandsaw blade on a good bandsaw, freehand does a quicker job and simpler besides, since, as you notice the end of the shaft just in front of the tenon must be sloped in towards the centerline by about 2 degrees. To do this accurately on a table saw consistently required more precision than I could easily muster. |
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Notice the slight 2-degree inslope of the end of the shaft. That makes neck setting much later on somewhat easier. I've machined out the headblock with a notch to clear the truss rod cap. The mortise in the headblock fits the tenon with a loose, rattle fit. That will forgive any number of small inaccuracies that tend to accumulate during the handbuilding process. The bolts will lock the heel smack-tight against the soundbox, with no vibrational losses. |
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Here I am using my partner Harry Becker's ingenious headstock drilling and shaping jig. After using the jig for drilling, it's removed, flush-bolted to the headstock and used as a router platform for shaping its outline. |
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What's occuring here is the shaping of the headstock.
Note that the holes aren't drilled in strictly straight lines, but 1 and 6 are moved
slightly closer to the outside edge, and 2 and 5 are moved in a bit closer.
This insures that each string coming off (and behind) the nut can trace a straight line
to its corresponding tuning machine post without running into the windings from an adjacent tuner post.
Martin does this on their headstocks. Note also the small sandpaper plane that I've fashioned from a piece of scrap. This allows me to true small edges flat and square, keeping edges sharp and crisp. |
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I'm trying out a new double-acting truss rod, designed by my old teacher, Michael Gurian, and sold through Stew-Mac. It promises to solve problems that may arise when the neck back-bends after carving and fretting, by enabling me to straighten the neck in either direction (my own rod only acts to bend the neck back against string tension, but does nothing to bend the neck FORWARD as may be necessary after fretting--the fret tangs sometimes acting as minute wedges that impart a slight back-bend to a neck that becomes apparent only after the shaft is carved. By the way this rod design worked great, and at $19 each, I intend to stop making my single-acting rods from now on. Whichever rod you use, you should imbed it into a snug slot that's routed by a round-bottm veining router bit which cuts into the shaft as deep a slot as you dare: the lower the rod sits in the neck, the more effective it's action. BUT you must beware and plan carefully because if you carve the neck and exposed the rod--or even come closer than 0.1" from the rod slot--your neck is toast. |
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And here, I've proceded to bandsaw the heel contour off the square blank. That's reserved bandsaw with a 3/16" scrolling blade. |
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On to fretting the fingerboard. The fingerboard carriage has replaceable fret-sticks (the yellow wood along it's edges) with slots exactingly cut to different scales. My finger points to the small key that indexes into the slots and positions the saw blade for the next crosscut. The saw is a .025 ker, hollow ground variety saw blade. $95 from Thurston Mfg. Co. Stew Mac sells a cheaper one but it's not hollow ground. |
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The board is double-face-taped to the fixture carriage, and the radial arm saw blade cuts a series of accurate fret slots at the correct interval. |
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The slotted fingerboard has been tapered according to our earlier layout diagram, which accounts for the desired nut width, scale and string spacing at the bridge. |
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The board is glued on, sandwiched between two rigidly straight cauls. I don't use nails or pins to keep the board from creeping: I just keep my clamps in good order, and apply the clamping pressure judiciously to avoid the fingerboard from sliding around. In the past, I've used locating pins, but have found that carelessly-applied clamps can succeed in dragging the fingerboard off the line regardless. So I save myself a couple of steps by not using locating pins, and just rely on deft manipulation of clamps to insure that the fingerboard stays where I want it. |
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After the glue dries, I proceed to plane a radius into the fingerboard. I just plane until it looks right, checking often that it remains longitudinally straight in the process. People ask me what the radius is that I take it too, and I reply that I don't know, 'cause I just do it to a familiar finished product. I just look at the crook in my outstreched index finger and approximate it to that. But I will choose to arch it more or less: proficient musicians like it flatter, amateurs like it more radiused. |
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The plane facets are sanded off with a 80-grit sandpaper plane. My two fingers index on the side of the plane to insure linearity of my stroke. If you let the plane cross the arch diagonally, that's bad. So I try to keep awake while doing this. |
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Here we see the board with a modest arch. The fiixture at the end of the fingerboard, keeps the fingerboard tab straight, and provides a hammering platfore during the following fretting steps. |
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YOU LEARN WHEN YOU TEACH Dept.: For years I used the same kind of shoemaker's hammer to fret my boards as my teachers did. Then I had to repair the occasional dings in the frets and fingerboard a natural result of the technique. Then a student showed me a Stanley dead-blow plastic hammer. After I stopped scoffing at him, I tried it and was sold. I wish I had run into this thing 30 years ago. I can wail away at the fingerboard and frets now with no consequence save for perfectly seated, un-crushed frets. |
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The heel-shaping procedure begins with a template mark that determines what part of the block stays on the guitar and what part ends up on the floor. |
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I carve off the waste to the template line with my "bellied" chisel. (It's in the book). |
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Further shaping of the heel with a skew knife, also called a "violinmaker's skew". The sequence is extensively documented in my book. |
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And more trimming. If your knife is sharp you can virtually take it just short of sandpaper. |
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Before shaping the shaft, I reduce the neck's thickness by 1/16 with a rasp, tapering from full thickness at the heel. This procedure will make the neck more comfortable and allow me to conceal the headstock scarf joint line. |
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The neck shaft being little more than a spoke-shaped object, what better tool to accomplish that than... a spokeshave? |
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I've drafted a pleasing contour line at the transition between headstock and shaft... |
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...and proceed to whittle the transition with my skew knife. |
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With the neck shaped satisfactorily, I proceed to fit the neck to the soundbox. I have to fuss with the heel and the opening at the mouth of the soundbox to get both to seat comfortably together. |
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The bearing surfaces of the heel must be painstakingly trimmed to allow the neck and soundbox centerlines to align, as well as to set a preliminary neck set-back. Again, a homemade miniature sanding plane is a great help. |
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The neck has been bolted on the soundbox for the following step: You can't see it, but under the clamps is the heelcap. It's seat at the end of the heel has been tipped at the same inclination as the back of the soundbox. The clamps hold the cap smacked up tight agains the soundbox, so it will emerge as glued accurately onto the end of the heel. |