Posted on

Calculating Soundbox Volume

Calculating Soundbox Volume

by Dave Raley

Originally published in American Lutherie #70, 2002 and Big Red Book of American Lutherie Volume Six, 2013



Want to design a new guitar shape and maintain an equal volume of enclosed air by adjusting the height of the sides? Here’s how to calculate volumes. Accuracy is a function of how long you want to spend measuring and calculating.

Consider two bodies: Figs. 1a and 2a. The body in Fig. 1 is 18" on the X axis and 4" on the Z axis. Suppose that you wish to make the body in Fig. 2 have the same volume as the body in Fig. 1 while maintaining the same X axis. Fig. 3 defines the axes regardless of the way the figures are turned.

Become A Member to Continue Reading This Article

This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page.

If you are already a member, login for access or contact us to setup your account.
Posted on

Questions: Musty Instrument Odors

Questions: Musty Instrument Odors

by Ed Pastor

Originally published in American Lutherie #66, 2001

 

Kelly Johnston from Cleveland, OH asks:

Is there a safe way to get a musty smell out of an old and valuable guitar?


Ed Pastor of Hemphill, TX
answers:

Make a sachet of cedar shavings (Western red or Tennessee cedar should work) in a piece of panty hose or fine gauze, place inside of soundhole if one is present; if f-holes are present, squeeze the sachet into one of the holes and suspend for several days to a week. If there is a case with the instrument, place it in direct sunlight outdoors for at least four hours and then place a small sachet of cedar shavings in the case. ◆

Posted on

Constructing an Under-Saddle Transducer

Constructing an Under-Saddle Transducer

by R.M. Mottola

Originally published in American Lutherie #68, 2001 and Big Red Book of American Lutherie Volume Six, 2013



Piezoelectric transducers or pickups (I use the terms interchangeably) are popularly used to “electrify” acoustic instruments, and are increasingly found embedded in the bridge saddles of electric instruments as well. Manufactured transducers are available from a number of sources, but this article provides instructions for making an undersaddle piezo pickup for a flattop guitar from basic materials. If you know which end of a soldering iron to grab hold of, you can build this pickup.

Piezo material will generate an electrical charge when mechanically deformed. There are four types of piezo materials used in the manufacture of instrument transducers: lead zirconate titanate (PZT) ceramic chips, PZT ceramic “bender” disks, polyvinylidene fluoride (PVDF) plastic film, and PVDF coaxial cable. PZT chips find their way into first-generation undersaddle guitar transducers, transducers for various bowed instruments, and manufactured archtop guitar and mandolin bridges. PZT disks consist of PZT material bonded to thin brass disks, and are commonly used for soundboard pickups for flattop guitars and for bridge-mounted pickups for upright basses. PVDF film may be found in all sorts of transducers from undersaddle guitar transducers to under-bridge-foot transducers for bass viols. PVDF coax cable is manufactured just like the single-conductor shielded cable used to make instrument cables, except that instead of an insulating material between the center conductor and the outer shielding braid, we find PVDF material. It is used in manufactured undersaddle pickups for acoustic guitars and is the material that will be used to construct a transducer in this article.

Become A Member to Continue Reading This Article

This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page.

If you are already a member, login for access or contact us to setup your account.
Posted on

Letter: Vacuum Clamp

Letter: Vacuum Clamp

by David Haxton

Originally published in American Lutherie #67, 2001

 

GAL:

I share Jon Calkin’s enthusiasm for the dished workboard (see AL#65). I know it’s made my guitars better. But he could trade all his clamps and dedicated workstations for a much simpler and, I would say better, solution: the use of a vacuum pump. You get absolutely even clamping pressure across the entire face of the plate and no dents from over-tightened clamps. In fact, I preshape and sand all my braces before gluing, lessening the need for chisel work after glue-up, and the whole procedure is quicker. I’ve also used my vacuum pump to make radiused sanding blocks for fretwork and laminated linings, and they make great hold-downs. My pump came from a mail-order surplus supply company for about $80.

Posted on

A Special Guitar Neck Modification

A Special Guitar Neck Modification

by Ralph Bonte

Originally published in American Lutherie #103, 2010



Last week I was able to make someone very happy. Christophe contacted me through my website, in pursuit of a luthier who could help him with his problem. Four years ago he had an accident while cleaning up the bushes surrounding his house. He was working with a wood chipper and wearing safety gloves. To make a long and painful story short, had he not worn the gloves he would have lost the tip of his left thumb. Due to the gloves, his thumb got caught in the motor of the chipper and was torn out of his hand, causing troubles for the muscles and tendons in his arm. Christophe used to be a recording artist playing the guitar. It took him four years of physical therapy to overcome and adapt to the new situation.

In the past year, the urge to play the guitar again became overwhelming. However, he could no longer play a regular guitar since he lost the support of his left thumb. He tried a prosthesis, but that didn’t work. He found it too awkward. When I read his message, I immediately agreed to do the work, although I did not know how I was going to do it.

Become A Member to Continue Reading This Article

This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page.

If you are already a member, login for access or contact us to setup your account.