Time to start the top. After jointing the edge is checked on the light box. Joining these plates will be tricky as they are already thicknessed close to final thickness at 3.2mm. The two sides of the join will have to stay flat when glued as there is no sanding leeway.
I have used a number of methods for glueing tops and backs up, some involving lots of clamps and wedges. The current method I use is the "tenting method" that I learned from the OLF and has a wonderful simple elegance. First the plates are joined with tape on one side pulling the plates tightly together at the join - the tape has some elasticity which helps here.
Then the plates are hinged back like a tent against the top exposing the edges to be glued.
I use hot hide glue, and here is my set up - Mothercare baby-bottle warmer (a tenth of the price of an electric glue pot), digital thermometer and a recycled Titebond glue bottle.
A bead of hot hide glue is run down the edges and the plates pushed down flat with the taped side down and the joint resting on some baking parchment to catch squeeze-out. Brown tape is then stretched across the top making sure that the plates a lying flat along the join. This has to be done quickly as you have around a minute before the glue starts to gel. The plates are then left to dry. After around 10 minutes most of the glue squeeze-out can be cleaned up with warm water but this needs to be done carefully as you can end up cleaning it out of the joint and opening the plates up again - don't ask me how I know this!!!
29th May 2006:
While the top joint is drying I am proceeding with the neck - cutting the scarfe joint for the peghead. I use a simple jig that I have made and my bandsaw.
The peghead is trimmed to close to final thickness so that the tuners will fit. The two parts of the scarfe joint are then sanded/planed for fit.
I'm using hot hide glue for glueing the scarfe joint so a dry run is essential to make sure everything fits and works given the short working time of the glue. I use the same jig to glue up the scarfe joint.
30th May 2006:
The top glue is dry and the joint has been cleaned up. Next the rosette is installed. The channel is routed.
A dry run fit of the rosette is done. The rosette is Kingwood with bwb purfling on the inner and outer edge.
I use white pva glue for my rosettes put in the channel.
The rosette and purflings are pushed into the glue and held down flat with a caul and weights until the glue dries.
Here's the completed rosette after sanding and scraping.
1st June 2006:
Plans . . . a lot of builder work from detailed plans that show every detail to the nearest micron. All of my guitars have been designed by me based on composites of instruments I like plus my own ideas, so my "plans" tend to be a little on the fluid side. Certain things have to be absolutely right - bridge location, body/neck joint and soundhole placement. Others can evolve as I work with the design and the pieces of wood - placement of some braces and number of fingerbraces etc. The plans for Bealtine I am using are shown here, and the next step is to mark where the X braces will be and the size shape of the bridge-plate and soundhole re-inforcement plate.
The soundhole plate is made of Lutz spruce and has the grain running at right angles to the top. The bridge-plate is Brazilian rosewood withe the grain angle offset to the top. The bridge-plate edges are bevelled so that they blend nicely into the top, and it's thickness is around 2.2mm. Here the two pieces are tested for fit.
First the soundhole re-inforcement plate is glued down using hot hide glue. A spruce caul is used faced with baking parchment to stop it sticking. Hide glue can be messy but the gelled glue squeeze-out can be peeled off after about 10 minutes and the rest cleaned up with warm water.
The bridge-plate is then glued on using hot hide glue - again using a spruce caul with baking parchment.
2nd June 2006:
The soundhole is now routed out. As I will be putting a side soundport in this instrument the soundhole is 104mm diameter. I start the rout on the back - any mistake and the re-inforcement plate can be routed off and a new one fitted. Not so easy for the top!
The route is completed from the top.
The soundhole has been cut and the top is cut oversize.
The back is cut oversize and the brace positions marked.
Guitar making involves many "jigs and reels" - well jigs anyway! I use a 10' radius for my backs and the braces have to be shaped to this. I got the design of the jig to do this from Mike Doolin.The brace is placed in the jig, pushed down and the wing nuts tightened. The bottom of the jig has a 10' radius.
The brace is sanded level on my belt sander and when the wing nuts are released . . .
. . . out pops the brace with the right shape. I am using raw braces of just over 7mm width and 16mm height for the back.
I use a hybrid X braced/ladder system for my backs as I like the curvature it gives to the back and helps with the instruments projection. The back X braces are notched at the joint and I glue them on one at a time on the go bar deck using hot hide glue.
Here's the back after the second brace has been glued. It is important to have the humidity controlled at between 40-500 while bracing and until the box is closed and I like to complete this process as quickly as possible.
The process for the top X braces is similar, except I use a 13' radius. The raw braces are 9mm wide and 16mm high.
