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The "G" Thang Acoustic Guitar Body Outline Design Tool
In American Lutherie #97 I wrote an article about a simple model which can be used to design the outline of an acoustic guitar. The model consists of five circular arc and three straight line segments for each half of the body. Although quite simple, this model can be used to accurately draw most "standard" guitar body outline shapes as well as a lot of nonstandard ones. The article described how to use the model to draw guitar body outlines, on paper, or using CAD drawing tools. An even easier way to design guitar body outlines is to use "G" Thang software, which is available for Windows computers and can be downloaded for free here.
Initial appearance: Wednesday, March 18, 2009
Last updated:
Sunday, October 11, 2009
About "G" Thang
The process of designing a guitar body outline is an iterative one. You take a good guess at what you want the outline to look like, draw it, evaluate your drawing, and then make modifications to it. The process can be tedious when done using CAD drawing software and is even more so if paper and pencil are used.
Some number of years ago, with the aid of another engineer, I developed an interactive script for use with an off brand CAD software package that made the process of designing the outline of the acoustic guitar simpler and quicker. Although originally intended only as a demonstration of CAD scripting tools, I used this script on and off during the intervening years, even though each use required me to re-learn how to use the off brand CAD software. But I needed to generate a number of body outlines for the above mentioned American Lutherie article, and this provided the impetus to convert the CAD script to a stand alone program.
"G" Thang uses the five arc, three straight line segment model described above, and provides features so you can iteratively and interactively make changes to your body outline design. The software "knows" a lot about the proportions of guitar bodies, and provides guidelines and other helpful facilities to make it easy to design your own body outlines. "G" Thang also includes a number of standard guitar body outlines, so you can start your own designs from one of these standards if that is the way you want to proceed. Once you are satisfied with your design, you can either export it to CAD or drawing software via a .dxf file, or you can simply read line segment locations right from the "G" Thang window for use in your paper and pencil drawings.
There are two common body outline styles that cannot be rendered using the five arc and three straight line segment model used by "G" Thang - the OM style and the Selmer Maccaferri style use a two arc lower bout, and "G" Thang just doesn't support this. I'd like to update it sometime to support these styles though. If you have an accurate CAD drawing of either of these body outlines you can help this effort by sending me a copy. Thanks.
Downloading "G" Thang
"G" Thang runs on Windows machines that have screen resolution of at least 1024 x 768. The main window is quite large, and higher screen resolution settings are preferred. But it will run on systems with 1024 x 768 resolution if taskbar properties are adjusted. See the documentation with the program for more details on how to do this.
The program is available for free download and may be used with no restrictions save that it may not be redistributed.
Download "G" Thang 0.5 (5.1 MB)
By the way, I would highly recommend getting a copy of both American Lutherie #97 and American Lutherie #99 and reading the articles on body outline design and cutaway design. These serves as good background documentation for using of "G" Thang. Of course, all serious luthiers are members of the GAL and get American Lutherie as a benefit of membership. You should too!
The "G" Thang guitar body outline design software is unsupported, but I would be interested in hearing from anyone with bugs to report or features to suggest.