Back & Binding Jig

Last Sunday, I had some time, and the scrap left from my molds, so I began my binding jig.  The construction is less complex than it looks.  I began with the plastic that would serve as the router mount, and cut it to size.  In the picture, the router is mounted backward, and I still have some work to do on the mounting plate, but it's width is correct and that was the crucial dimension.

Next, work on the interior box.  On the material for the interior box (3/4 MDF) I cut the groove for the mounting plate on the table saw with a dado blade.  It took a bit of fussing with shims to get the width of the groove correct, but I wanted a tight fit.  Next, I cut the sides to width, about 2 1/2 inches, and length.  The drawer glides determined the length.  With the mounting plate in the side grooves, used that to get the measure for the width of the back.  I used a simple butt joint, then glue and brads to build the box.  You can use the mounting plate to keep things aligned.

The next step was the exterior box.  Again, I cut the sides to width, about 2 1/2 inches.  Again, the interior box and the drawer glides determined the height.  It is set so the router, at the lowest level, will not bottom out its bit.   A word on the base.     You can see in the photo above and to the left, that it is flush with the front, but extends back.  When the jig is in use, I plan to clamp it behind to one edge of my bench, and you can see from the photo that it supports the weight of my router without the clamps.

I built the exterior box in the same way.  The width of back was determined by the interior box, with the drawer glides.  I then used a simple butt joint with brads and glue.  I cut and installed the base last.  When the glue had dried, and I'd rounded over all the edges, I installed the drawer glides.  Make sure you get the orientation right, but basically the interior box slides up and down like a drawer in and out.

Next, I need to fuss a bit with the router mount, and build the guitar cradle, but on the whole, this project went together better than I would have anticipated.

I had ordered the back and side plates from LMI.  I was side tracked a bit.  Originally, I had intended to use mahogany, but got side tracked by the idea of black walnut, a domestic wood.  It arrived on Wednesday, so I was able to get a start on the back of the guitar.

I brought the thickness down some with my toothing plane, and my thickness sander.  With the toothing plane, I only worked the interior surface.  It's quicker than the thickness sander alone.  There was a bit of tear out, but the thickness sander removed it along with the toothing plane tracks.  

The center stripe is maple from the local hardwood store, with black/white perfling on either side.  The stripe, as you can see from the back view goes all the way through, and is not an inlay.  I prefer this to an inlay, particularly since the joint is reinforced.  The assembly needs a little fussing to get it all lined up in the lattice jig, but then I don't need to worry about sanding through the inlay.  I used scraps from the soundboard redwood to make the reinforcement strip.  Once I had glued it in place on the on the go-bar deck (using every go-bar I had to insure even pressure along the length) I planed it level, then planed a slight bevel on either side, which is rounded over when I sand it.  Today, I will work on the bracing for the back, which I intend to make from walnut, also purchased from the local hardwood store. 

Prepping and Joining the Plates

I re-sawed the plates for the sound board at the college before the Christmas break.  I ran them through the thickness sander until they were approximately the right thickness, then used my jointer to prepare the joint.  In the absence of a jointer, one could use a shooting board, and I know that some luthiers prefer the hand method regardless.  I do have a jointer, however, and it works perfectly fine.  I take the two book matched plates, and run them over the jointer together and I get a tight joint that stand up to the light test (holding the joint together and trying to see light through it).  My secondary test is that it squeezes out glue uniformly along its entire length.  That too tells me the joint will be tight.   


I used the lattice jig, pictured, left to join them up.  It worked precisely as advertised.  I glued the seam (using titebond) rubbed it until the glue began to set, then put it in the jig.  I wrapped the ropes in a criss-cross pattern loosely over the jig, then the loose ends I wrapped around one end, then drove the wedge shaped slats under the criss-crossed ropes.  It pulled the plates together sufficiently, and kept them dead flat while the glue dried.   You'll note there is no wax paper under the slats, but the slats themselves were well coated with wax before the glue up. 


The jointed plates are pictured at right, and you are looking at the exterior side.  After all the fussiness with the making of the rosette tiles, it was almost shameful how easily the plates went together with the jig.  You will note that there is a slight difference in color on either side of the center line.  The plate on the right has oxidized some, but as I do the finished sanding, that difference should disappear.  The next step will be the leveling of the top and the inlay of the rosette.  If all goes according to plan, I will tackle that in the coming weekend.