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PostPosted: Sat Mar 17, 2018 6:34 pm 
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Cocobolo
Cocobolo

Joined: Sun Apr 25, 2010 4:46 pm
Posts: 300
First name: Mark
Last Name: McLean
City: Sydney
State: New South Wales
Zip/Postal Code: 2145
Country: Australia
Focus: Build
Status: Amateur
Australian blackwood and lutz spruce
Blackwood neck (ebonized)
Macassar ebony fretboard and headstock
Blackwood bindings

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front.jpg

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front qtr.jpg

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back qtr.jpg

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back.jpg

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butt.jpg

This is definitely non-traditional, and I am sure it will not be everybody's cup of tea. I have some trepidation even showing it to you all. But here goes.....
I have built a handful of guitars, but never anything else. I wanted to do a bit of experimenting with this build, learn a few new tricks, and make something that is "not a guitar". But it is for myself, and I don't know how to play other instruments (yes - I know I could learn, but I am an old dog). So this is strung like a guitar, tuned a third above a standard guitar, and has octave strings paired with the 3rd and 4th string. This gives a sound much like a full twelve-string but it is easier to play. I also figured that if the nut is replaced with one slotted like a mandolin (4 double courses of strings) this thing could easily be converted to something like an octave mandolin.

I based this off one of the plans in Graham McDonald's Bouzouki Book, which is an excellent resource
(http://www.mcdonaldstrings.com/bouzoukibook.html). This is a flat-top, not carved, pressed into a 15-foot radius and braced with a X-brace, and lattice in the lower half. I fancied the idea of making it fan-fret, just for the fun of a new experience. After reading a bit about carbon fibre rod bracing, as outlined by Professor Turner and Professor Brentrup (and others), I thought I would give that a go also. The CF rods recess into the hollow neck block (this is Graham's design) and the tail block, which is ply.
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The blackwood was a set of orphaned guitar sides without a matching back. The sides were unusually long and I worked out that one piece would be long enough to do the whole body of the bouzouki (no butt-joint needed). The other piece could make a 3-piece back. Offcuts of the blackwood made the bindings and f-hole bindings. The neck is also blackwood, but I ebonized it using iron acetate. The fretboard and the headstock faceplate are from the one continuous piece of macassar ebony. Bridge is rosewood.

I tried to make my own timber tailpiece, with a macassar ebony/CF/blackwood sandwich which attached to a bolt into the tailblock (hence the t-nut in the tailblock in the picture below). This idea turned out to be a complete failure as it was not strong enough to match the string tension. Three different prototypes all failed before I gave in and bought an Allen brass tailpiece (RS-2 model) which turned out to be the perfect solution.

The scale length is about 23 inch on the bass side and 21 inch on the treble with a zero fret and the neck joins the body at (about) the 14th fret. The neck joint is one of the versions outlined in Graham's book, with no heel. Given that I had already thrown out any "traditional" look for this instrument I was happy to adopt a shameless bolt-on attachment for the neck. It is strung with 10-47 light guitar strings, and the octave strings are 0.012 and 0.007. I intended to tune it GCFBbDG (i.e. a third above standard) but the tension was a bit too high and I snapped a couple of strings. So at the moment it is tuned to F#. If I was doing this again I would probably make it slightly shorter scale so it can be tuned a little higher.

It is finished with a hand-rubbed satin hard-wax oil. Tuners are Gotoh mini-stealth. It sounds bright and brash - like a bouzouki, not a guitar. But very pleasing to my ear, and lots of fun to play. Thanks for looking.
Attachment:
headstock.jpg


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PostPosted: Wed Mar 21, 2018 1:02 pm 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Apr 08, 2009 9:34 am
Posts: 3081
Nice work, Mark! I like the sidebound black stripe...


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PostPosted: Wed Mar 21, 2018 2:36 pm 
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Brazilian Rosewood
Brazilian Rosewood
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Joined: Thu Feb 12, 2009 12:12 pm
Posts: 2844
First name: Bryan
Last Name: Bear
City: St. Louis
State: Mo
Country: USA
Focus: Build
Status: Amateur
That black neck is cool. I'll have to try that one of these days.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.


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PostPosted: Thu Mar 22, 2018 7:17 am 
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Cocobolo
Cocobolo

Joined: Sun Apr 25, 2010 4:46 pm
Posts: 300
First name: Mark
Last Name: McLean
City: Sydney
State: New South Wales
Zip/Postal Code: 2145
Country: Australia
Focus: Build
Status: Amateur
Ebonizing wood is quite fun. There are lots of guides on the web, but basically you make an iron acetate solution by allowing steel wool (or some other iron source) to rust in vinegar. This solution will produce a deep black stain in timber which contains a high tannin content. But the result is highly variable between timber species. It only stains the surface, down to a depth of 1-2mm, so you do it after shaping and sanding. It is easy to sand through the ebonized layer, but if you then apply more ebonizing solution it goes black before your eyes. Very cool. It is quite a different look from a paint or stain - it is actually incorporated right into the timber. It can be fun to play around with and you might find some interesting applications.


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PostPosted: Thu Mar 22, 2018 10:11 am 
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Koa
Koa
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Joined: Thu Dec 18, 2008 11:42 am
Posts: 1117
Location: Hudson, MA
First name: Kevin
Last Name: Quine
City: Hudson
State: MA
Country: Usa
Focus: Build
Status: Amateur
Gorgeous build. Does the fan fret configuration cause any problems re-aligning the bridge when you change strings?


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PostPosted: Thu Mar 22, 2018 4:27 pm 
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Cocobolo
Cocobolo

Joined: Sun Apr 25, 2010 4:46 pm
Posts: 300
First name: Mark
Last Name: McLean
City: Sydney
State: New South Wales
Zip/Postal Code: 2145
Country: Australia
Focus: Build
Status: Amateur
Hi Kevin
You are right - it is a floating bridge so you need to reposition it after removing the strings. But it is not hard to work out the correct position. You just measure the appropriate scale length for the bass side and the treble side as separate measurements. This instrument has a zero fret and the distance from there to the twelfth fret on the lowest string is 304mm, and on the top string is 284mm. Double those numbers and add some compensation (about 2mm on treble side and 4mm on bass, depending on string gague and action height). This will tell you where the front end of the saddle should go. Put the top and bottom string on first and get them to partial tension, then check the intonation using the 12th fret harmonic. If those two strings sound OK the others will be fine too. I put violin bow rosin on the bottom of the bridge to discourage it from skating around - but I am not sure that makes any real difference.

You only really need to go through the measuring process once. Next time you want to change the strings just mark the bridge position before you start using a couple of post-it notes stuck onto the soundboard to mark each end of the bridge. Then you can just plonk it back in the same place without needing to measure.


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PostPosted: Fri Mar 23, 2018 2:34 pm 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Apr 08, 2009 9:34 am
Posts: 3081
Everyone I know, mandolin or guitar, changes strings one at a time, thereby keeping most all of the tension on the instrument all the time. I know that on mandolins, it takes at least two weeks to a month to get back the tonal qualities if you remove all the strings and replace...


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PostPosted: Mon Mar 26, 2018 5:28 am 
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Cocobolo
Cocobolo

Joined: Sun Apr 25, 2010 4:46 pm
Posts: 300
First name: Mark
Last Name: McLean
City: Sydney
State: New South Wales
Zip/Postal Code: 2145
Country: Australia
Focus: Build
Status: Amateur
I have heard this said of guitars before - but have also heard arguments that it is a myth. I have not subscribed to this view and have many times removed all of the strings on a guitar. I have not been aware of any change in tone on restringing. However, I admit that I have not done any formal experimentation of this. And regarding mandolins, I have absolutely no experience.


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PostPosted: Mon Mar 26, 2018 3:10 pm 
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Brazilian Rosewood
Brazilian Rosewood

Joined: Wed Apr 08, 2009 9:34 am
Posts: 3081
Guitar players most always will change strings far more often than mandolin players. The guitar player is always looking for that "fresh", nearly new strung tone, while most all mandolin players HATE new strings and much prefer strings well broken in.
Many times when doing bridge work or re-fretting, I would restring with the old strings at the request of customer. They sounded awful at the start and took a lot of playing to "get back to normal". That alone was reason enough for me to change strings one at a time. There is absolutely no reason to take them all off unless the instrument is being worked on or slacked to ship.
That's my opinion...


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PostPosted: Wed Mar 28, 2018 7:25 am 
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Walnut
Walnut

Joined: Sat Jan 26, 2008 5:36 pm
Posts: 34
State: Oregon
This is excellent. Multi-scale can work on nearly anything.

You might experiment with string gauges. Seems you should be able to get the tuning you want with the scale lengths you have chosen.


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PostPosted: Thu Mar 29, 2018 5:29 pm 
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Cocobolo
Cocobolo

Joined: Sun Apr 25, 2010 4:46 pm
Posts: 300
First name: Mark
Last Name: McLean
City: Sydney
State: New South Wales
Zip/Postal Code: 2145
Country: Australia
Focus: Build
Status: Amateur
Thanks Jason. I planned it using the very nifty string tension calculator on Graham McDonald's website.
http://www.mcdonaldstrings.com/stringxxiii.html
This tool is invaluable if you are making something which is a bit off the beaten track, to get an idea of what scale length and string gauge will work best. I am sure that you are right and I will try some different strings to see if I can get it tuned just a little higher.

This is the first multiscale instrument that I have built or owned, and I had not even played many before. I really like it. Playing it feels completely natural. You are not even aware of the fanning of the frets, and it is actually more ergonomic than a normal fingerboard. If you look at your hand you will immediately recognize that your fingers are fanned, not parallel. And from a design point of view there are advantages in allowing the bass strings to have a longer scale length than the trebles. I think I will be doing it again on future builds.


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