Nautilus Acoustic Mandolin Prototype

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Project by JacobsonMandolins posted 09-16-2012 08:28 PM 2241 views 7 times favorited 3 comments Add to Favorites Watch

Progress on my project to develop an affordable, one-man shop, tap tuned, varnish finish, made-in-the-USA instrument by optimizing the entire construction process. This shows the first two prototypes. One is parallel braced and the other is transverse braced.

Instead of traditional binding, the sides are glued using an inflatable bladder around the assembled top and back plates. The neck is installed last.

All rough work is done using a CNC machine I built myself based on the FineLineAutomation plans and parts from It cost under $3000. Although it cuts paths “automagically”, it is still a VERY manual process, and requires thorough planning and constant attention to detail.

The construction is non-traditional, but it is intended to be a way to get very good tone out of an instrument that takes under 20 hours to build. I am getting close to that goal.

All the important parts are still “tuned” by hand, and many, many decisions are made along the way- including altering the G-code for each individual piece of wood and combination of materials in each instrument.

The grunt work, although enjoyable, is not cost-effective for me to do by hand for this price point, which is quite low for this market. ($1200 – 1500)

This method is not unlike the great builders of the 20’s and 30’s, just utilizing the great opportunities presented by modern technology.

Sound samples:

-- - building affordable mandolins and guitars with great tone and playability

3 comments so far

View scottb's profile


3648 posts in 5569 days

#1 posted 09-17-2012 03:02 AM


-- I am always doing what I cannot do yet, in order to learn how to do it. - Van Gogh -- --

View caocian's profile


47 posts in 5628 days

#2 posted 09-17-2012 03:09 PM

Great job. I love the concept and the results so far. Nice full, open tone as well. As an aspiring luthier, I have a million questions, but for now I’ll limit them to just one. Are you using a strobe tuner to tap tune the instrument? If so, what kind. I’m shopping for one and thinking about the software version (Strobosoft). Thanks. Again, beautiful job.

View JacobsonMandolins's profile


2 posts in 3322 days

#3 posted 09-17-2012 03:47 PM

Scott, thanks!

Coacian, feel free to ask as many questions as you want. You can see more details of this project at my Web site.

I do “tap tune”. And I do use a strobe tuner. But what I call “tap tuning” for my process is not a specific pitch target for every plate. The pitch each plate rings at may vary a bit. I think it is much more useful to look at the spectrum of frequencies using a spectrum analyzer or FFT tool such as Audacity’s “Plot Spectrum” command.
But it is just another variable. No decisions are made solely on what note a plate is ringing at… because there is never just one note which is the “resonant frequency” of a plate. There are several modes active at one time, and it changes depending on where you tap it, what you tap it with, and how much coffee you had this morning.
To limit these variables, I have a “fake rim” fixture which I mount the plates in for taking spectrum readings. This just cuts the variables down to where I tap, what I tap with, temperature, humidity, etc. Still a lot of variables.

More than anything else, I flex, scratch, and play with the plate in my hand as I refine the graduations. After a few builds, this will tell you much more than anything else.

Read Benedetto’s book and Lawenence Smart’s lecture to the 1995 GAL meeting on his web site for a better explanation than I can give.. and keep the questions coming.

-- - building affordable mandolins and guitars with great tone and playability

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