Archtop Guitar Build - Tail Piece

The more I thought about putting the final coats of finish on the guitar, the more I thought that this is a bad idea seeing that the finger rest, pickup, tail piece and bridge are not built yet.  If I finished the guitar I was taking a chance that one of these pieces would have problems, not fit correctly and something would need to be done to the front plate that would require redoing the finish.

The tail piece is made from ebony and I had to wait a while to find a piece on e-bay that was big enough to make both the tail piece and finger rest.  I looked around at different designs and really liked the tail piece design that McCarthy guitars uses.  Instead of having the strings sit through the tail piece in slots, they run their strings through holes bored into the front end of the tail piece. 

A 12 inch radius was cut into the top of the tail piece and holes were bored for the strings.  Corresponding holes were bored for the ends of the strings and channels were cut into the top to allow for easier passage of the strings.  I made mother of pearl inlays that match up in design and form to the fret markers.  The back of the tail piece had holes bored for the tail strap and channels were routed to accept the retaining nuts for the tail strap.  A channel was cut into the back and a fulcrum of ebony was installed.  I also made side bevels to make the tail piece look less "bulky".  I also used some color-tone black dye in water to make the ebony a uniform black.  Here is the end result with a couple of scrap strings in place to aid in checking the angle for the finger rest.

Archtop Guitar Build - Finishing Part 1

Finishing is a tedious but very important part of any project.  The guitar was gone over with a fine tooth comb to look of for any imperfections.  Any small gaps in the binding were filled with paste made from binding chips dissolved in acetone.  Small gaps in the wood were filled with Elmers glue and the wood was sanded to create dust which combines with the glue to form a custom paste that erases the gaps.   The bindings were scrapped and the guitar was gone over with 220 grit sand paper.

The guitar received a coat of thinned shellac and this sealed the wood and pointed out any areas where glue or other substances prevented the shellac from sealing the wood.  These imperfections were repaired and the process was repeated.  I liked the tone of the spruce with just the shellac on it and it should remain pretty close to this tone with the clear lacquer applied over it so this should be good to go.  I will make a alcohol based dye to tone up the maple to make more contrast between it and the spruce top.

Archtop Guitar Build - The Big Glue-Up

I have to admit that this is the part that I've been dreading, the final glue-up of the neck to the body.  For me the choice of glues was easy to make, hide glue.  This glue is very strong, acoustically dense and can be reactivated with heat and steam so if the neck should ever need to be re-set, it can be steamed off fairly easily.  The problem is that the dove tail joint is very tight.  You have to use both thumbs and bulge your eyes out to get it to move from the seated position once the neck is in place.  This is great because it should lead to a very strong joint.  The problem is that hide glue is mostly water and water makes wood swell and lots of water makes wood swell a lot.  If the joint is tight dry, it will be uber tight wet and it is possible that once the glue is in place, the joint will get stuck half way or even worse about 90% of the way in.  To make matters even worse, hide glue gets really sticky as it cools so from the moment the glue is applied it is cooling and swelling the wood, both very bad in terms of getting the joint together.  Hide glue is known to have very little "creep" to it.  Creep is what you get when you put two flat pieces of wood together in a butt joint and put wood glue between them.  When you first bring the pieces together and put pressure on them, they want to skate around on top of each other because the glue initially acts as a kind of lubricant in the joint.  Hide glue is very tacky as it sets so once you put the pieces together, they don't want to move so you had better be accurate with your initial set up of the joint.

The solution to this is to heat the wood to be joined to increase the time the hide glue stays hot.  Also, you must be sure that the hide glue has been in the glue pot long enough to get uniformly hot.  I heated both sides of the joint with a hair drier to get the wood warm and also made sure that all of the clamps and cauls were set and ready to go.  I applied the glue to the joint and to my surprise the whole glue up was very anti-climatic.  The joint slid together easier than when dry and seated easily.  The clamps were applied and I wondered why that went so well?  I think the answer is that when hot and wet, hide glue feels a lot like, well um snot.  That is because it is mostly animal protein and long chain lipids sort of like, well you know...  I must have kept the joint hot enough so that no setting took place before the joint was seated so the whole thing went together easily.  Here is a photo of the glue up.

Archtop Guitar Build - Headstock and Neck

Shaping the neck looks intimidating but it really isn't (overall, this is the fourth neck I've shaped).   Every make of guitar has a little different feel to it's neck.  Some are wider or narrower, some have a round profile while others are more oval or even "V" shaped.  One of the beauties of building your own guitar is that you can make the neck just the way you like it.  My favorite neck as far a feel is concerned is my Laravee acoustic so that is the neck that I copied.   Cut the profile to match and rough in the shape.  I used a spindle sander but you could use a spokeshave, plane, belt sander or whatever you have handy.  Be careful not to overdo the rough shaping since it is a lot easier to remove wood than it is to add it.  I find that a pattern guide is handy to get the shape to match exactly.  I used a random orbit sander for the fine tuning the shape.   How the neck feels in your hands is the final quality assurance step.

I then routed the channel for the headstock binding and installed the plastic bindings.  I usually install each layer of binding individually and build up the layers one by one.  The advantage of this is that you can use butt joints instead of cutting miters.  This time I tried laminating the thin .020 black and white together to make the installation easier but the miters were a bear and ended up making the process take a lot longer than if I had done it the way I always do.  I used butt joints on the outermost layer of .040 while with .020 black and white on the bottom (this was a one piece build-up).

The headstock mother of pearl inlay was laid out and cut.  The detail of the inlay required having the black epoxy seep through to fill the fine cuts in the design.  I routed this a little later at night than I usually like to work (because bad things happen when you are overly tired) and I was a little sloppy in some of my cuts but the black epoxy covers over a multitude of minor errors.  The piece was loaded with epoxy and a level was used to insure the headstock was flat because the thin epoxy will self level, even through cracks only a few thousandths of an inch wide.

Here is the end result of the headstock inlay and binding process.

One other thing that I should point out is that I changed the geometry of the nut slot from what the plans call for.  Benedetto likes to run this fingerboard and headstock binding as one continuous line.  I think this looks great but the way he does it is by having the bottom of the nut slot run at an angle that matches the headstock angle.  This means that the bottom of the nut has to be cut at an angle to match the headstock angle.   I would really rather have my nut sit in a perfectly flat and square slot.  This will make fitting easier and could improve the guitar's tone because the nut/neck interface is an important part of transfer of string vibrations to the guitar itself.  I made my flat of the neck (for the fingerboard) a little longer and used four layers of black veneer to make the top of the headstock hit the nut in such a way that the binding material for the headstock can be wide enough to visually match the fingerboard binding.  You can sort of see that in this photo of the finished neck.

It is now time for the final fitting of the neck to the body.  A piece of carbon paper with a strip of blue masking tape on the back for reinforcement was used to mark the high spots on the back of the neck extension.  These high spots were removed with a scraper and the process was repeated about twenty times until a uniform dusting of black was seen across the joint.

This is one point that I'd like to make for anyone building an archtop.  The landing area for the neck extension is something that you need to think about early in your build.  When you make your templates for the top plate, make sure that you leave a perfectly flat landing area for the headstock extension.  This will make the fitting of the extension much easier when the time comes.  I sure wish I had done that...

Archtop Guitar Build - Fret and Neck Work

I left the neck as a solid block because it would make support for seating the frets very easy.  I usually seat my frets with a dead blow hammer but I got a fret press with 12 inch radius insert from Bob when I bought the radius beam.  Wow, what a nice tool!  The frets seated well and easily but the fret press really shined in the area over the neck extension.  Just shim up a support and gently press the frets into place.

Now that I don't need the support of the neck block, I trimmed the neck to shape, added the extension for the nut channel as well as ears for the headstock.  We're getting close now...

Archtop Guitar Build - Fingerboard and Neck Extension

The neck for this guitar is made from a single piece of maple so there are a few aspects of this type of construction that I will take advantage of.  The neck was planed square, the headstock angle was cut and a channel was made for the truss rod.  I am using a Stewart Mac "Hot Rod" dual action truss rod for this guitar.  I purchased a spiral cut router bit that was exactly the same size as the truss rod width so the fit would be perfect. A dovetail was cut into the end of the neck to connect it to the body.

The fingerboard extension was something that I thought about long and hard.  The plans call for cutting a 5/8 inch rabbet into the end of the neck and then trimming away about half of the material to thin it out enough to allow the neck to sit low enough to allow a distance of 3/4 of an inch to be obtained if a straightedge is held over the fingerboard and extended over the body to where the bridge sits.  The problem with this way of attaching the neck extension is that you remove a perfectly cut dove tail with the rabbet and then have to re-cut that dove tail into the bottom of the fingerboard extension and this entails carving into a blind corner.  I thought about this and came up with this alternative.  A dovetail could be cut into fingerboard extension instead and this strong joint could be used to attach the extension.  This would allow you to fit the neck into the body and remove the fingerboard extension for frequent trimming of the extension to get the fit just right.  This is what the neck and fingerboard extension joint looked like.  The truss rod is also in place.

The fingerboard was run though my model making table saw to cut the fret slots and the taper was also cut into the sides.  Plastic binding material was run around the edges and mother of pearl inlays were prepared.  I really liked the inlays shown on the plans but when I looked around, I couldn't find ones that matched them.  I bought a set of generic block inlays (like on a Les Paul Custom) and cut scallops into the edges to make them "hour glass" shaped.  I then cut them at a 66.6 degree angle and fitted ebony strips between the two pieces and super glued the three pieces together so I had to only make one recess for the inlay rather than two.  These were glued in using epoxy with a couple of drops of amber and black Stew Mac Color Tone dye added.  This makes the epoxy "ebony" colored and any imperfections in the routs are magically hidden.  The finger board was set in place and a couple of pieces of fine wire were drilled though two fret slots to act as indexes for the glue up.  I used hide glue for this so that if I ever needed to replace the fingerboard, I could steam it off.  Here is the glue up.

The fingerboard is a uniform 1/4 inch thick so a 12 inch radius must be cut into the surface of it.  I bought a 12 inch Stewart Mac radius block from Bob Gaffney (be sure to check out his very well done archtop blog) and installed two shooting boards into the sides of the neck block.  This is one place where altering the neck building process from that described in the book works out well.  By leaving the block intact I can easily mount it in a workmate, hold the fingerboard in its final position and also mount the shooter boards with screws so that the radius block always travels straight down the fingerboard with no deviation left or right.  Here is the neck and fingerboard after 100 grit sanding to a 12 inch radius.

Archtop Guitar Build - Disaster Strikes

Next up was routing the channels for the bindings.  I used a jig that I had built for binding the ukes and I had no problems routing the channel for the top plate.  When I was working on the bottom plate channel, I noticed that the body of the guitar had a lot more resistance to pushing it forward after the bit had passed the neck block.   I pulled the guitar body away and found that the spiral cutting bit had pulled itself forward in the chuck and had routed the channel about 1/8 of an inch too deep!  The side of the body was veneer thin over this channel and had broken though in one area.  I was sick!

When a disaster strikes, the first thing you want to do is fix it quickly but the best thing you can do is to back away and come back another day.  Taking time to think through the problem helps avoid making the problem worse by trying a quick fix.  There were a lot of options available.  My first thought was to fill the bad route with ultra-thin model airplane plywood to stabilize the side, that's the darker brown material in this photo.   I then planned on using matching maple veneer to cover the plywood core but I knew that I would never be happy with this kind of repair.  It was time to gear up for major surgery.

I sawed the back plate off of the guitar and stripped out the linings for this plate.  I then made new linings, installed them and leveled them out.  Here is the body with new lining, placed back in the building mold just before the back plate was glued on.

The new total depth of the body is 2 3/4 inches which is at the low end of acceptable per the Benedetto book.  The only problem is that the end pin hole is now closer to the back plate than to the front but this was a small price to pay for a better repair.  Here is the back plate being glued in place

I then invested in the Stew Mack binding router set-up.  It is very pricey but it works well and I knew that if it saved me from having to go through another major set-back it would be worthwhile.

 The new channels were clean and true.

 Plastic binding was installed on the problematic back plate and this is the end result.

 Here is the front plate with the bone insert for the tail piece strap.

It is nice to be back in business...