Bridges

Today I completed bridges for two instruments - the current 7 course Renaissance lute and the replica Stradivari guitar. I decided not to photograph the actual carving procedure, as it simply involved using a knife to remove everything that didn't look like a bridge. The ebony and bone overlay on the Strad was a fiddly bit of business. The European pear carves so nicely, almost as if it has wax incorporated somehow in the grain. The fun part came when I drilled the string holes. I have in my possession a Black and Decker drill from the late '50's which is wonderfully precise, and has a Jacob's chuck that will hold a 3/64" bit. I weighs twice what a modern cordless does, it's geared very fast, and it emits an interesting ozone smell when used for long periods. Perfect for this job.

Making some points

Today I am fitting some points to a lute body. Here are a couple of pieces of ebony which I've planed to the appropriate thickness and taped together to encourage symmetry in my carving. I drew a little arc for guidance, but it's only a rough indication. I'm just aiming for an interesting curve.

My pride and joy. This is the sharpest knife I've ever owned. It's a small slojd pattern forged for me by Del Stubbs http://www.pinewoodforge.com)/

It's capable of powerful shaping cuts, but the tapering design allows for really delicate work too.

A couple of swift carving motions leaves this result. I'll use some thin double-sided tape to fix these in position and trace around with a fine pencil.

A scalpel blade ensures a clean cut. I aim to bisect the pencil line down it's centre. The little "o" is a reference mark to keep track of which piece goes where.

When the glue (fishglue in this case) hits the freshly cut spruce, it will swell the fibres just a bit. A little firm pressure is sufficient - they don't need to be clamped down. It's hard to make out in this photo, but I've left the spruce in the area of the top block just a bit thicker than need be. I learned this one the hard way- it's much easier to scrape it down to the level of the points than vice versa. Cleaner too, as the ebony dust loves to lodge in the pores of the spruce, leaving a dirty grey appearance.

The ebony fingerboard overlaps the sides of the neck by a small margin to allow me to blend the curve later in the final scraping. Note the arrow indicating grain direction near the nut. It's another precaution to make sure I don't end up crushing black dust into the lute's face during leveling and scraping. I'll press a couple of tacks in place at the nut end to keep the board pressed firmly against the points.

Surgical tubing. It's the most positive clamping system. Robert Lundberg apparently used a series of laboriously shaped cauls, which I find interesting - given that he used rubber strapping to glue on neck veneers. Strange.

Here's another instrument on the go these days. It's a five course baroque guitar. Points originated as a pragmatic solution to to cover up repair and alteration work as larger necks were grafted to old instruments when more strings were added. Interestingly, by the time the inspiration for this guitar was fashioned in the early 1700's, they had become a design convention and were fitted to new instruments at the time of their construction.

Cases.

I have yet to find a manufact-urer in North America that produces lute cases. The only options for a novice builder on a budget seem to be limited to ordering a beautiful (and costly) custom case from England, making do with one of the accessories designed for the so-called "student" lutes imported from Pakistan, or to construct your own.
I decided to take a shot at the latter. The material I'm using goes by the trade name Sintra. It's a medium density expanded PVC used in the sign industry. I recall experimenting with it in art school. It bends readily with heat, is very stable, durable and pretty inexpensive. I envisioned using this handsome mold to heat-form the case sides. As it turned out, the mold is unnecessary! I found it easier to just use a drawing for reference angles.


To effect the bends, I clamped the Sintra in place over a board and applied gentle pressure using a piece of scrap wood to keep the line of the bend square. It doesn't take much heat! Sintra has gained a following among the strange subculture of Star Wars aficionados who like to dress up in storm-trooper armor. There are several excellent YouTube videos of fans molding the various pieces necessary to become Boba Fett. All very entertaining. I'm working with 6mm material, and it has the right combination of stiffness and weight.






A quick check with this ancient ebony and brass bevel. You can see that the Sintra has compressed slightly on the inside corner and taken on an attractive radiused appearance on the exterior.








It's possible to correct overbends while the material is still warm by gently coaxing it. I left the ends long, marked the case center line on them, and trimmed them to fit. The joints were reinforced with a strip glued on the inside. I planned the dimensions so that one case would accommodate a number of lute patterns by adjusting the padding and neck support placement.

I used regular plumber's PVC pipe adhesive to join things together. This substance is nasty! In fact, it's so toxic that although I worked outside when gluing large areas and used a respirator, I think next time I'll try a slow cure epoxy instead. To be clear: this is just a demonstration of my method. If you decide to replicate it you do so at your own risk and I will not be held responsible for any damages! Do not put your health in danger.

Here I'm clamping a secondary thickness in the area where the piano hinge will go. Similar reinforce-ment is placed under each latch and the carrying handle. I fastened the hardware using small 1/8" round headed bolts, with washers. I wasn't sure I trusted the Sintra's capacity for holding screws.








With the top and bottom glued in place I used a bearing guided roundover bit in my laminate trimmer to clean up the edges. A block plane worked well to remove the bulk of the overhang. Even with a vacuum hose held close to the bit, there was a whirlwind of plastic fuzz everywhere! The green tape was a precaution to keep the solvent-based adhesive from spilling and staining the case walls. Speed is of the essence and it's hard to be neat. It's best not to slow down the feed rate of the router, as the Sintra can melt if the friction becomes too great.



I used a standard woodworking marking gauge to delineate the parting cut between case top and body, then finished up the job with repeated knife cuts -which are remarkably clean. All in all, Sintra is a very friendly material to work with.
















I'm fortunate to live close to a specialty foam supplier. I lined the case with some 1" closed cell foam and adhered it with a hot glue gun. This was a fun experience, but it took about a day's labor. Also, it's not nearly as classy in appearance as the Kingham cases. The materials amounted to about $100. It seems there really is no such thing as an inexpensive lute case.