Always an exciting time when the bodies hit the finishing closet and start to get shiny. This is the spare room, can be closed off, and is pretty dust free. Still a bunch of work to do on the necks, but getting a good finish on the bodies always takes longer.
I got some spalted tamarind logs from a mango grower I got to know (also have some mango logs he saved for me) and it is pretty spectacular, but (I have not resawn most of it) it is probably going to be a bit too narrow to make a tenor. I’m thinking of trying a 3-piece back, like some older guitars. Something like a piece of curly koa as a center triangle, and black & white spalted tamarind for the other back plates and the sides. Like this:
As I build out the shop here in Florida, I have come across an unexpected benefit of setting up a second shop. I purposely did not bring down a number of jigs/fixtures that I have made over the years, with the intent of re-making them so that I do not have to carry than back and forth. In the process of re-making them I have had the chance to incorporate a number of improvements that I have thought of over time. There always seems to be something more important to do than re-make a jig is basically works, even though there are some aspects which are a bit of a pain, require more setup, and extra clamp here and there, etc. When you have to make them fresh, there is no excuse not to incorporate evolutionary ideas. I like my new jigs, and may re-make the ones up north when I get back there.
The binding is finished on all 6 instruments, meaning that it is installed, and things are all sanded down nice and flush so they all can get their first real coat of sealer, and I can get to see how things will really look under the final finish. Result – I am very well pleased by all 6 instruments. One tries to pick out binding that will work well with the back and side wood, but until it is all installed, and you get the first coat of finish on it, one never really knows. Particularly with some new binding.
I got some quilted sapele cut-offs from a place that saws guitar wood that was just big enough for me to turn into binding. While the ‘quilted’ nature is a bit subtle on the scale of binding I am very pleasantly surprised how well the red-brown color of the sapele goes with the sycamore back and sides. It is a really nice warm look. Could easily become one of my favorite bindings for a sycamore instrument, koa being the current top contender, again because of a rich warm brown color.
It is time to do the binding. This involves routing small ledges in the sides of the instrument for the purfling and the actual wood binding. To do this I have a router bit which takes one of a set of bearings, which are graded in exact small increments.
The first cut is a wide and shallow cut to establish the inside edge of the purfling. I take digital calipers and measure the thickness of the purfling and the binding. The sum of these becomes the size of the bearing I use. I made a new base for my small trim router which provides much more stability and place to grip with both hands than trying to use the small base which comes with the router. This wide base makes it easy to keep the router vertical. As you cut one cuts ‘down hill’, that is, from the outside of the curve toward the center of the instrument. Doing this, because of the direction of rotation of the router bit, minimizes the chances of chipping and tear-out. I do apply a layer of sealer to the instrument before doing the routing and this also helps minimize any chipping or tear-out.
Once this first wide and shallow cut (only as deep as the purfling which is thin) is made, then the bearing matching the thickness of the binding is used to cut the narrow but deeper ledge around the instrument. This leaves a two-ledge edge onto which the purfling & binding are glued.
The binding and purfling is pre-bent and is attached with some strong sticky tape. (I’m transitioning from orange to stronger brown tape here). You apply glue with a small paint brush to a couple of inches, press (hard) and tape down the purfling & binding, and move on to the next area. The tricky spots are the ends meet where you want the purfling and binding to meet with no visible seam.
I apparently was not, but I did not realize the error of my ways until I was looking at the pictures while reviewing the last post to this very blog. But first, a little humor.
“Luthier” is a French word that means “one who swears a lot”.
Now the specifics: If you look carefully at the previously posted pictures you will note (as I did) that one of the ukuleles does not seem to have a side sound port. But I put side sound ports in virtually all the instruments I build these days, what’s wrong? Well, I glued the top and back onto the wrong side of the sides. Since I put the sound port in first, this means that the port was on the right side of the instrument rather than the left! [insert luthier swear words here] What to do? I could just continue and make this a left-handed instrument, but I have only ever had one call for a left-handed instrument, so I did not want to do that. I briefly considered other things like putting in another sound port so there would be two, one on each side, but rejected all these ideas. The only real solution was to practice my ‘de-construction’ skills, meaning, take the top and back off the sides, and then glue them on the right way.
So I got out a syringe of water and an iron to heat things, a sharp knife for separating the seam, and went at it. Things went better than I expected, and in an hour I had both the top and back off, with no damage to either. Put back the blue tape with the arrow indicating the top, which is my usual practice to avoid just this situation (which I must have done backwards before), clean the edges up, and things are ready to be glued on the correct way.
-Crisis averted. Lutherie is a continuous process of covering up ones mistakes!
The bodies of the 6 ukuleles, 3 concerts and 3 tenors are all closed up, meaning that the top and backs are all glued on and the edges trimmed. Now comes a lot of sanding.
I sand the sides with a block to make sure that things are nice and straight and flat (across the side) so that when the router runs around to cut the binding channels things start out nice and flush. I sand things to 150 grit and then put on a coat of sealer before I cut the binding channels. I use CA glue as a sealer/pore filler, and a coat of this really hardens the surface grain which prevents chip-out when routing the binding channel and prevents glue from gluing in the binding from soaking into the adjacent side, which makes clean-up much easier. A lot of sanding, but things could be worse than working outside in the Florida breeze, listening to the birds, watching the osprey fish in the pond while sanding.
I’m working of 6 ukuleles at once this time. When I was getting things together to bring south, there were just too many nice pieces of wood, so I ended up with 6 sets, instead of the usual 4. 3 concerts and 3 tenors. I have the sides all bent and glued to the end blocks, and the side sound ports cut and bound.
The backs of most modern musical instruments have a slight arch to them, they are not flat. The slight arch makes the instrument stronger, and allows expansion and contraction with changes in humidity. As the back swells with increased humidity the arch gets a little higher. I use a pretty standard arch which is a circle with a radius of 15 feet. The back braces are also cut with this 15 foot radius arch so that when they are glued to the back, the back has the desired arch. The braces are glued to the back in a dish which has the same 15 foot radius cut into the surface. One can buy these radius dishes, but they are (in my mind) pretty expensive, so I have cut my own. As I build out the shop here in Florida, I need to cut some new dishes.
To cut a dish I made up a jig which is a channel just the width of a router base. The bottom of the channel is made with some thin plastic trim molding which is bent along a 15 foot radius line. Then as the router is run along, it cuts the 15 foot radius line. The dish has a center pin, so you just rotate the dish and re-run the router along the channel. A great project to do outside on a cool and breezy day because it makes a lot of sawdust cutting that dish out of a piece of plywood. When you are done with the router a quick sanding to take off any unevenness and fuzz, a coat of shellac to seal the surface, and you are good to go.