BODYBUILDING with Lazy radicals...

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Re: BODYBUILDING with Lazy radicals...

Postby Michael James » Wed Jun 17, 2015 3:38 pm

Today I am leaning towards some sort of very tight "basket-weave" to create back and sides. With some glued in linen linings, perhaps.

Anybody here been doing that sort of thing?
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Re: BODYBUILDING with Lazy radicals...

Postby Michael James » Fri Jun 19, 2015 3:08 am

Still undecided! But I got my rough-cut cello neck in the mail today... :-)

Photo4894.jpg


Will dowel those peg-holes, and do some sort of veneer over top!
It's really dry maple, and has a lovely ringy-pingy tap tone.

Now I've had a chance to take some measurements, been back to work on the blueprint ( leaning towards single-cutaway now)

MandoCelloV8-19.png


Definitely fixed on the 19 inch scale length... and after much consideration, decided (at least provisionally) to skinny down the body thickness.
Looking at 3.4 inches now, including the (flat) top.

Was hoping I could get some advice on how to best make a super-big edge radius on the top . I'd like to have it extremely rounded, shooting for one inch eadius!

Have a couple of ideas:
BigEdgeRadius-HollowedThickTop.png

First would just to use a one-inch-thick spruce top, and cut away most of it on the inside.


BigEdgeRadius-TopSetIntoLedgeInRim.png

Another idea would be to make a one-inch-thick "rim" around the whole top edge of the "sides", and then set a thin spruce top flush into that
( it would have bracing, etc underneath...)
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Re: BODYBUILDING with Lazy radicals...

Postby Bryan Bear » Fri Jun 19, 2015 11:28 am

IMO, the easiest way would be to put a 1" thick rim and glue the soundboard on top of that then rout your round over instead of trying to inlay the top into a recess. You might want to consider releiving some of the mass of that rim on the inside before you put the top on.
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Re: BODYBUILDING with Lazy radicals...

Postby Michael James » Fri Jun 19, 2015 11:15 pm

Yes, you are right, that would be a lot easier...

But any way I choose to do a "rim" - it's still going to have the obvious visible "banding". So I'll have to mock that up and see if I like it.

Today I was thinking that instead of a one-wood "rim", I could build up a rim out of dozens ( hundreds??) of little "blocks" - and create a sort of gigantic checkerboard binding visual effect, to use that rim to visual advantage - something like a modern-day Baja quinto or Baja Sexto often has...
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Re: BODYBUILDING with Lazy radicals...

Postby Michael James » Sun Jun 21, 2015 3:27 am

Wow, I was passing through a nearby city today and stopped in at a music store with a very well equipped acoustic room.

Played a bunch of guitars, mandolas, banjos, banjolins. ukes, resonators, ect.

Surprisingly, the loudest and richest instrument in the whole room was an open-backed five string banjo with a metal rim.
The exact same open-back model with a wood rim was a bit softer. Various full bodied banjos ( some very expensive!) were much quieter - and some weighed a TON.
Most of the resonator guitars they had were fairly ordinary - sounded much like a normal acoustic.

I'm pondering, what's need for a back at all? That open back banjo sounded THREE TIMES AS LOUD as the $1000 mandola hanging next to it.

Now pondering if my Mandocello needs to morph into a banjo-cello!!!??! Or maybe an open backed resonator mandocello?

Incidentally, I've never touched a banjo in my life before, but found I could navigate around on them quite easily ( they seem to have some sort of open tuning)
Pondering if I should go back on Monday and grab that banjo.... :roll:
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Re: BODYBUILDING with Lazy radicals...

Postby Clay Schaeffer » Sun Jun 21, 2015 11:44 am

The reason banjos are loud is because they have a super light weight skin head and a bridge that transfers the string energy quickly into it. Loud and quick attack and short sustain.
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Re: BODYBUILDING with Lazy radicals...

Postby Michael James » Sun Jun 21, 2015 6:20 pm

So, what do we need for 'loud' with long sustain???
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Re: BODYBUILDING with Lazy radicals...

Postby Randolph Rhett » Sun Jun 21, 2015 8:04 pm

Michael James wrote:So, what do we need for 'loud' with long sustain???

Build a piano :D

Seriously though, if you add "sweet tone" to loud and long sustain you have exactly what all luthiers are trying to figure out. Mostly everything is a trade off. Want it loud? Sounds harsh and banjo like. Want it rich and tuneful? What happened to the volume. Want both? Build it light and big and watch it collapse after a few years/months/days. Add to that most people a trained to hear a '60's Martin as "guitar sounding". Build it too differently and many people won't like it.

People have been working pretty hard on this guitar thing for several generations and haven't come up with many major breakthroughs for a reason. That having been said, I encourage you to build what speaks to you and never stop experimenting. An opened back banjo/guitar may just be the instrument you have been looking for!
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Re: BODYBUILDING with Lazy radicals...

Postby Clay Schaeffer » Sun Jun 21, 2015 10:45 pm

So, what do we need for 'loud' with long sustain??

A solid body and electricity.... :D
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Re: BODYBUILDING with Lazy radicals...

Postby Michael James » Mon Jun 22, 2015 10:55 pm

Well, perhaps we can look at the opposite side of the equation. What is it about a banjo that actually REDUCES the sustain of the string?

I think that pesky 'conservation of energy' law rules out the string vibration (once set in motion by a pluck of finger or plectrum) ever INCREASING.
So it's not that a piano, or sturdily-built guitar is actually 'making' the string vibrate louder, longer - rather it's just allowing it to continue vibrating at fairly high amplitude for as long as the initial impulse was able to swing it.


So, what is it about the banjo soundboard that makes our plucked string lose its energy (amplitude of vibration) so quickly??
After the initial attack, is the 'springy' banjo head actually ABSORBING the vibration of the string?
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Re: BODYBUILDING with Lazy radicals...

Postby Michael James » Thu Jun 25, 2015 3:10 am

OK... a bit of research has cleared that up.... I see it's a trade-off between the string energy being dissipated all at first attack... or sustaining longer, albeit softer. Higher impedance soundboard keeps the energy in the string longer, etc. Complicated stuff!

Looks like this is fast morphing into a resonator mandocello. One with a removable back (attached via some tiny neodymium magnets).

And I have an idea for some kind of "nice" removable body now... with some sort of "i-beam" that stretches out from the neck to the tailpiece - and the soundboard / body assembly suspended in between.... I'm thinking of something along the lines of those "RiverSong" guitars from Kamloops ( I visited their factory last year...)

Sketch is REAL FUZZY... must ponder!!!
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Re: BODYBUILDING with Lazy radicals...

Postby Michael James » Fri Jun 26, 2015 2:27 am

now with a seven-inch resonator cone... side views still very much work-in-progress :-)
MandoCelloV9-reso-19.png
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Re: BODYBUILDING with Lazy radicals...

Postby Michael James » Thu Aug 20, 2015 11:50 pm

Well... laziness ("the mother of invention") got the best of me, so I decided to give this project the "clamshell" configuration, two thick slabs of Western Red Cedar sandwiched together and extensively hollowed out inside. (before joining!)

Probably with carved out "integral" bracing here and there. And possibly some carbon fiber stringers directly connecting the neck block to the tailpiece.
(Tailpiece design still very much undecided!)

That orange blob is some extra maple I will have to add to the neck heel, in order to support the last six or eight frets worth of fretboard...

Image
Attachments
ResoMandoCello-side(rough).png
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Re: BODYBUILDING with Lazy radicals...

Postby Michael James » Sat Mar 24, 2018 11:24 pm

Wow, two and a half years have passed and I still haven't cleared the bench for this! I guess the woods are getting more and more seasoned!
Have ALL the hardware ready, and neck and fretboard and body woods, AND also have an MDF routing template of the body outline (cut for me by a CNC company in NY).
Maybe this will be the year I finally start to make some sawdust! :)
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Re: BODYBUILDING with Lazy radicals...

Postby Carl Peberdy » Wed Mar 28, 2018 1:48 am

I've just read this post - sounds very interesting - please make shavings and finish it! I'm very interested to see, and hopefully hear, how your various ideas turn out.

Cheerio,

Carl
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