the symmetrical tricone

John Morton · Post by **John Morton** » 25 Apr 2013 8:40 am

The National tricone is a beautiful thing, but the obsessive/compulsive builder with a metal shop just had to try for bilateral symmetry. But then I spoiled it with the 7 string peghead. There were the usual setbacks, I was a bit hasty trying to put it together in time for a show in Portland this weekend.
John

Rick Stratton · Post by **Rick Stratton** » 25 Apr 2013 8:46 am

Wow, that's great!
Nice work!

Mike Neer · Post by **Mike Neer** » 25 Apr 2013 8:59 am

John, just a masterful piece of art. You nearly killed me with these pics. Jonesing for a tricone....

chas smith · Post by **chas smith** » 25 Apr 2013 10:16 am

WOW, WOW, and seriously, WOW!

Michael Kienhofer · Post by **Michael Kienhofer** » 25 Apr 2013 1:44 pm

Any-more build Pics John? Just love seeing these put together!

Allen Hutchison · Post by **Allen Hutchison** » 25 Apr 2013 2:00 pm

Wow, magic beautiful job, congrats.

Is that head stock aluminium?

David Matzenik · Post by **David Matzenik** » 25 Apr 2013 2:33 pm

Stunned!

Post by **Brad Bechtel** » 25 Apr 2013 2:47 pm

What a cool looking instrument! Where in Portlandia will the guitar be displayed?

David Cook · Post by **David Cook** » 25 Apr 2013 2:51 pm

Like that wide string spacing

Rockne Riddlebarger · Post by **Rockne Riddlebarger** » 25 Apr 2013 3:30 pm

Amazing! Incredible! Awsome! What more can I say?

Mike D · Post by **Mike D** » 25 Apr 2013 4:36 pm

Very cool John, always love your work.

Now...do you really have a bandsaw big enough to cut out that buck from one piece?!?

John Morton · Post by **John Morton** » 25 Apr 2013 4:52 pm

Thanks for all the kind words.
The Portland event is the Northwest Handmade Instrument Show at Marylhurst College.
http://www.nwmusicalinstrumentshow.org/

I used to snip everything, but now it's a CNC milling machine for the geometrically precise bits.
Here are some more shots from the process:

layout for top and back

top blank on the mill table

grill patterns have been cut

a test of the die that recesses the grill

tray rim ready for assembly

tray pieces w/ assembly form

I use a block mold, a rectangular block which is cut to the body shape in plan and elevation. There is a guitar-shaped piece in the center, and the various other pieces aid in clamping parts of the assembly as they are soldered. Everything goes back together like a 3D puzzle. (Mike D, my upper blade guide goes up to 12", that's enough to cut one side.)

the cone blank is cut from flat alum. sheet

the cone is spun over an aluminum form

after spinning

the spiral grooves are done freehand

Mike D · Post by **Mike D** » 26 Apr 2013 7:19 am

Awesome set-up and tooling. I made all mine with an electric nibbler, a couple small hand nippers and a Dremel.

Spinning cones looks like fun.

Tom Pettingill · Post by **Tom Pettingill** » 26 Apr 2013 8:13 am

What a beautiful instrument John!

Brian McGaughey · Post by **Brian McGaughey** » 26 Apr 2013 8:20 am

Wow! You are a true craftsman, John.

How does it sound?

John Morton · Post by **John Morton** » 30 Apr 2013 7:35 pm

I have made other guitars with this profile, which is a Weissenborn shape reduced by 15%, therefore a 23" scale. The largest tricone array that fit in the shape was 4.5" diam. This one is much deeper, which makes for a fuller sound. Also the reorientation of the cones allowed me to return to 6" cones, which probably helps the bass.

At the moment the tuning is a G arpeggio running 2 octaves from D to D, therefore a full step below standard guitar tuning with a scale shorter by 2". This suggests that I could run that tuning up as much as a 4th to C. I'll try that soon, wearing my safety glasses ...
John