Friday, February 20, 2009

Binding the Bodies

The bodies are bound. Let me show you what that entails.

A bit of patience is required as I do everything the hard way.

The purfling cutter is again used to score for the rebate.To keep the purfling cutter blade sharp it is honed repeatedly throughout the scoring process. I use polishing compound on window glass. This is also how I keep my chisels razor sharp. What am I talking about? Razors aren't that sharp.The waste is carefully pared away in specific stages. At all times the chisel is never allowed to face good wood. First I shave off the corner.Then I create a new rebate with the chisel, just within the scored lines. This is carved deeper and wider until a paper thin layer is left against each scored edge. This is carefully pared away with the chisel starting in the scored line.I use a little trick to carve the point on the cutaway. Prior to carving the rebate and several times during, I saturate the fibers with superglue. Just a drop or two will soak in right at the tip and you will never loose any cross grain. But you still have to be careful.You get into a rhythm with the carving of the rebate. It is pretty intense work, since you can't make any mistakes, but it is very satisfying.The body bindings are made just like my veneer, ripped on the table saw with a 1 1/4" sawmill blade and a guide fence.Then thicknessed in the sander. I make the bindings slightly thicker than my standard 3/32" veneer so there is a bit more left to work with in final contouring.Sawn into strips that will fit just proud of the rebate, they are allowed to soak in water for a couple of days. This set up with the bottom of a torn dust collector bag works well.The wet strips are run quickly over the hot pipe and when flexible they are tacked down to a tracing of the actual rebate. As they cool and dry the brads are added and the curves are faired with hand pressure.The whole board is then propped up in front of the wood stove to bake for 2 or 3 days.The bindings are an almost perfect fit when they come off the board. Any small flat spots are trued up on the hot pipe and the cutaway is glued in first. Each successive piece overlaps the previous one. A shaped caul faced with sandpaper is used to true up minor discrepancies that show up when the actual binding is offered up to the rebate. Working around the body each piece is laminated in place. Stategicly located clamps allow for continuous clamping pressure all around the curved edge. The glue will scrape very easily off the polished edge of the body, so I don't worry if it drips all over. With this set up I have plenty of time and can saturate both the binding and the rebate with glue.By shaving the first strips back at a very shallow angle a perfect scarf joint is formed. Once pared back and rasped flush the seam is very difficult to locate. This binding is on for good.

Lots of work for one little piece of wood, no? I think it's worth it.

Monday, February 9, 2009

New guitar update, Neck build up

I think more work goes into the neck than any other aspect of the guitar. Especially on an electric.

For truss rod installation I can but follow the manufacturer's instructions. I use the Allied Luthier's Supply, stainless steel, two way adjustable, low torque rod. It is roughed up with a file.The neck is dadoed for a very snug fit. And a hardwood spline is fitted over the top.

The filler strip is epoxied in place with light pressure. The strip sinks in more at the center as the rod is compressed against the adjusting screw. During clamping I check the action of the nut to get it tight, but still free.

Once the epoxy has cured the strip is pared and scraped flush. Note the walnut plug that fills the end of the dado at the body end and acts as a stop for the truss rod end.
The fingerboard marquetry is fully cured prior to laminating the boards. The three layers of veneer are pinned to mdf cauls and clamped up. The laminations are left under pressure for about 2 days. It is very important to keep the boards flat until they are fully cured.
This process produces a very flat and stiff finger board. The edges are cleaned up on the edge sander and the nut end is checked for square.
Fret positions are then marked off on the board. This clamping arrangement of the scale allows for hands free marking. I made my fret slotting saw from an old back saw. By carefully filing and sanding the blade along just the bottom 1/2" I achieved a very stiff blade with the perfect sized kerf. I filed a dozuki style tooth and it cuts on the pull stroke. Even so, it requires great care and concentration as no mistakes can be made. Note the pine strips that act as a depth stop. When the blade just scores these carefully thicknessed strips the slot is the correct depth. The actual kerf stops just past halfway through the middle layer of veneer. This leaves a lamination below the kerfs, running the full length of the board.
Once the boards are slotted, they are tapered on the edge sander to their final dimensions. Both the finger board and the neck are left long at the body end to accommodate veneer pins. These are just #19 1/2" brads with the heads snipped off. Note the stack of three finger boards in the back. Nice and flat, no?
A carefully shaped Ash caul is used to laminate the fingerboard to the neck. Precision is of the utmost importance. The center is checked and rechecked, then checked again. But the pins prevent most movement and lots of glue can be used. Once the board is fully cured it is cut through at the 22nd fret. The waste is carefully pared away, and the pins removed.
This gives me a first hand look at the laminate bond of the fingerboard. My process results in one of great strength, I think.In the rebate that is formed by the fingerboard the neck bindings are laminated with the use of a tapered and waxed spline.The ends are mitered and the mitered end cap is glued in place with this little set up. Nice, no? The maple binding is very springy and there is clamping pressure to spare. When the glue is cured the bindings are rasped flush with the board.Headstock veneers are precut for the truss rod nut and carefully scraped smooth on the back.
The headstock wood and veneer are oversized to allow the placement of more veneer pins. A temporary waxed wood nut is used for alignment. The nut end of the veneer is also pre shaped to the correct angle. This is done by hand on the edge sander. It is offered up to the wooden nut for a perfect fit.

To make laminating the headstock easier the caul is glued together and faced with wax paper to be applied as a single unit. Using 4 veneer pins ensures a precise placement.
Binding the headstock is a bit more tricky. Once the headstock is sanded to shape, a purfling cutter is used to score for the rebate.

Great care is taken to ensure that no tearout occurs at the corners.
The waste is then chiseled out. Very carefully, as no mistakes can be made.
The rebate is made perfectly square and smooth with a paring stroke. Headstock veneers such as this cherry burl, would be shattered by a router. Note the cross grain at the corner. I think maybe this is only possible by hand.

Bindings for the headstock have to be bent. I use this little set up. The pipe has an old chore boy stuffed in the end for a difuser.

It works well though, and it dosn't take long to shape the bindings.

The bindings are glued on in stages. I use a soft nylon cordage, wrapped tight for excellent clamping pressure.
Having lived on a sailboat, I know not to ever cut a line in two. But with this clamping set up the extra length can be put to use on the end bindings.
The successive stages are trimmed back with the dozuki saw.
Then the ends are pared back and filed flush in preparation for the next set.

The side bindings go on last.
Note the awesome squeezeout. This binding is on for good. The precision is such that there will be no need for even the tiniest amount of filler.
Glue won't stick to the nylon cordage either, just unwrap it and there it is.Once things are cleaned up with the rasp and riffler, things are starting to look very good, I think. Note how I leave the neck square for most of it's length. This makes clamping in the vice for bindings very easy.
That's all for now. Next time we should see some carved necks and maybe something that even resembles a guitar.

New guitar update, Body Construction

The new guitars are moving right along. I'll bring you up to date.

The top layer of each core is screwed in place and the body is rough cut to shape on the bandsaw. I use a 1/4" blade to cut right to the line. Screws are 3/4" and positioned at the neck mortise and bridge pickup locations, where the holes will later be routed away. Note that the cutaway is left uncut at this time.The bodies are then separated and the lower two thirds routed for the cavities and wiring. On the first two guitars I installed the shielding through the control cavity after glue up and it was tedious. This time I put it in first. I laminate it with contact adhesive, and "iron" it into place with a soft wood caul.Then the top layer is laminated in place. Precision line up is greatly facilitated by the two positioning screws. By leaving the cutaway filled in, pressure is evenly distributed in this area for a superb lamination.

Routing the maple bodies results in the removal of approximately 1 1/2 lbs from the core (from 8lbs to 6 1/2lbs). The reduction in weight is only partly responsible for the routing of the cavities. I also think it sounds really cool to say my guitars are "semi-hollow body." Ha!Meanwhile the backs of the finish veneer panels are carefully scraped smooth. The steel punch is used to hone the scraper.Then it is back in the press, with everthing carefully lined up. Note that the cutaway has been cut away (he he) prior to laminating. After the glue has cured the panel is trimmed back with the fret saw.In order to reduce the chance of tearout the veneer is brought flush with the rasp before proceeding. A router or laminate trimmer here, with all the grain changes, would be too risky.My first electrics were shaped by hand. Since I built them one at a time it was no big deal. This time around I have a new toy for the drill press. I'll admit it, there is no way I can beat the prescision of this tool. Not if I was there all day with the rasp. So I cheat a little on the handwork.
And it is very precise indeed. The bodies are shown here ready for binding. I make sure the edge is perfect prior to cutting the binding rebate, and take it to 400 grit. Note that the back veneer panel is not yet in place. This allows me to not worry about scratching the back as I work the bindings, etc. The back veneer will go on at the last possible moment.