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the symmetrical tricone

Posted: 25 Apr 2013 8:40 am
by John Morton
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

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Posted: 25 Apr 2013 8:46 am
by Rick Stratton
Wow, that's great!
Nice work!

Posted: 25 Apr 2013 8:59 am
by Mike Neer
John, just a masterful piece of art. You nearly killed me with these pics. Jonesing for a tricone....

Posted: 25 Apr 2013 10:16 am
by chas smith
WOW, WOW, and seriously, WOW!

Posted: 25 Apr 2013 1:44 pm
by Michael Kienhofer
Any-more build Pics John? Just love seeing these put together!

Posted: 25 Apr 2013 2:00 pm
by Allen Hutchison
Wow, magic beautiful job, congrats. :)
Is that head stock aluminium?

Posted: 25 Apr 2013 2:33 pm
by David Matzenik
Stunned! :whoa:

Posted: 25 Apr 2013 2:47 pm
by Brad Bechtel
What a cool looking instrument! Where in Portlandia will the guitar be displayed?

Posted: 25 Apr 2013 2:51 pm
by David Cook
Like that wide string spacing

Posted: 25 Apr 2013 3:30 pm
by Rockne Riddlebarger
Amazing! Incredible! Awsome! What more can I say?

Posted: 25 Apr 2013 4:36 pm
by Mike D
Very cool John, always love your work.

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

Posted: 25 Apr 2013 4:52 pm
by John Morton
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
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top blank on the mill table
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grill patterns have been cut
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a test of the die that recesses the grill
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tray rim ready for assembly
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tray pieces w/ assembly form
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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.)
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the cone blank is cut from flat alum. sheet
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the cone is spun over an aluminum form
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after spinning
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the spiral grooves are done freehand
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Posted: 26 Apr 2013 7:19 am
by Mike D
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.

Posted: 26 Apr 2013 8:13 am
by Tom Pettingill
What a beautiful instrument John!

Posted: 26 Apr 2013 8:20 am
by Brian McGaughey
Wow! You are a true craftsman, John.

How does it sound?

Posted: 30 Apr 2013 7:35 pm
by John Morton
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