ocarolan
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Post by ocarolan on May 24, 2013 15:37:54 GMT
Shortly after the East Anglia Guitar Festival weekend with markthomson and davewhite I sneaked this little snippet largely unnoticed (except by Martin !) into grayn 's thread ... Had some interesting discussion with Dave over the weekend about octave mandolins (aka octave mandola). (Enignatic smiley) Keith Dave hasn't made an octave mandolin before, but with the obvious success of the Ceol Binn mandolins, I speculated to him that maybe a Ceol Binn on steroids might turn out very nicely, and be a useful addition to his already large range of instruments. Dave was interested, but, first things first, he had to have a name for the potential instrument before giving the matter too much more thought! We settled on Ceol Binn Mor, which, roughly translated, means something like Ceol Binn (sweet music) on steroids. I had found by experimenting on my bouzouki, that a capo on fret 3 or 4 gave me a workable scale length of around 530-500mm which made melody playing so much easier than on the full scale zouk. Dave set to that very weekend with scale length and string tension calculations (based on my zouk experimentation), plus a rough plan of magnifying the Ceol Binn mandolin shape to see if it looked to be a workable proposition. We also had a rummage in his workshop and picked a set of Colombian Rosewood and some Euro Spruce, plus some purfling strips in black/pear/black to delineate the bindings as these are to be Colombian Rosewood also, as are the headstock veneers. Rubner tuners, as on the Road Trip mandolin will be used. The neck will be mahogany with carbon fibre reinforcement plus an adjustable truss rod. Since that weekend there have been emails flying back and forth wrt shape, dimensions, cases etc, and the DeFaoite Design Workshop (ie Dave plus Debbie's aesthetic input re body shape) has come up with some "final" drawings and specifications. Dave has started a new build section on his website for Ceol Binn Mor, and will also be chronicling the progress of the build here on Acoustic Soundboard too. In fact, he may well be along quite soon..... Keith     |
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Phil Taylor
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Post by Phil Taylor on May 24, 2013 15:43:05 GMT
Nice one! Phil |
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davewhite
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Post by davewhite on May 24, 2013 15:56:57 GMT
In fact, he may well be along quite soon..... Speak of the Devil . . .  When Keith gave me his ideal scale length and measurements of nut width and string spacing at the saddle, together with my “Chief Design Consultant” aka Debbie I started to design an instrument as an expanded version of my “Ceol Binn” mandolin – roughly 40% bigger. We came up with this initial design:  Trying to find suitable cases for these sorts of instruments is a bit like finding hen’s teeth but I eventually managed to find a large bodied bouzouki case that was very close in size:  The upper bout area of the initial design needed a little reworking to fit the case and so a new set of “cunning plans” emerged. Sometimes function has to come before form:  The case will need further customising as the neck support will need to move “south” slightly but as this part is just screwed in from the sides of the case it will be easy to do. There is also room to build another storage compartment into the case above the headstock. Next the main components are assembled:  Specifications are: Scale Length: 530mm Top: European Spruce. Back/Sides: Colombian Rosewood Headstock: Solid, Colombian Rosewood veneer on front and rear of headstock. Lower bout width: 380mm Overall length: 860mm excluding strap pin. Maximum rim depth: 85mm Soundhole/Rosette 88mm diameter soundhole. Colombian Rosewood rosette with black/pear/black inner and outer purflings. Soundport: Side Ebony soundport on bass side upper bout. Neck: Mahogany, bolt on with adjustable truss rod and twin carbon fibre rods. Tuners: Gold Rubner tuners with Ebony buttons. Nut/width: Bone, 42mm Saddle/String spacing Bone, 48mm Bridge: African Blackwood with bone saddle. Tailpiece: De Faoite brass/Columbian Rosewood or Gold trapeze for ball end strings. Strap-pins: Gold the treble side neck heel. Fingerboard: Ebony bound with ebony, black/pear/black side purfling, 16-20” radius, Plastic side dot markers. 18 frets, Jescar FW47104 EVO. Binding: Colombian Rosewood with black/pear/black purfling on top, sides and back. Macassar ebony end graft with black/pear/black side purflings. Ebony heel cap. Finish: Hand rubbed pre-catalysed lacquer. String gauges: GDAD/GDAE: 0.014”, 0.022w”, 0.032”, 0.049” Pickup: K&K Pure Western Mini Case:Acoustica Hardcase Next step is to make a bending form and mould to hold the bent sides and rim-set. |
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Post by grayn on May 24, 2013 17:07:07 GMT
Oooooh, that's looks very cool.
Beautiful wood choice.
Will it be ready for Halifax?
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leoroberts
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Post by leoroberts on May 24, 2013 19:46:56 GMT
Magnifico! I spotted your allusion, Keith, but didn't want to be disappointed by nothing happening  This looks like a thread that's going to be worth following (as are all the build threads, to be honest!) |
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ocarolan
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Post by ocarolan on May 25, 2013 15:55:20 GMT
Oooooh, that's looks very cool. Beautiful wood choice. Will it be ready for Halifax? Oh yes Graham, all being well! Magnifico! .................. This looks like a thread that's going to be worth following (as are all the build threads, to be honest!) Agreed - but especially in this case! Keith |
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Martin
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Post by Martin on Jun 4, 2013 10:03:19 GMT
Exciting stuff, Keith! I'm looking forward to following this one! |
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davewhite
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Post by davewhite on Jun 8, 2013 18:00:42 GMT
How many luthiers does it take to change a light bulb? Just one but first they have to make a jig  . Here’s the mould to hold the rim-set . . .  . . . and here’s the bending form:  The Colombian Rosewood sides are thicknessed and a hole for the "porthole" soundport has been made in the bass side. The ebony centre of the "porthole" is cut and tested for fit:  The neck-block curve on the sides is bent on the hot-pipe:  Next the sides are bent in jig. The sides are sprayed lightly with water, wrapped in brown paper and sandwiched as slat, side, slat, heating blanket, slat and the neck end clamped down to the bending form. The blanket is switched on and when hot enough the lower bout shape is bent:  After fine tuning on the hot pipe and some initial trimming here’s the bent treble side in the mould:  Tomorrow I'll do battle with the other trickier side - the one with the porthole in it  |
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leoroberts
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Post by leoroberts on Jun 8, 2013 19:08:49 GMT
Looking good, chaps  |
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ocarolan
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Post by ocarolan on Jun 8, 2013 22:38:47 GMT
Ooooooh - good stuff Dave! Keith |
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davewhite
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Post by davewhite on Jun 10, 2013 14:30:54 GMT
Here’s the bass side bent in the mould:  Next the mahogany neck block is made. This is a two piece construction The two pieces are roughly shaped and glued together using hot hide glue:  The neck block shaping is finished, two 6mm holes drilled for the carbon fibre internal braces, the bolt holes drilled and the slot for the fingerboard support cut - the final depth of the slot will be determined when the neck is fitted. The mahogany tail block is made with two 6mm holes drilled for the internal carbon fibre braces:  Next the neck-block is glued to the sides with epoxy using the mould as a jig:  |
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ocarolan
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Post by ocarolan on Jun 10, 2013 16:06:18 GMT
Love the wedging system to keep the neckblock in place! Keith |
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davewhite
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Post by davewhite on Jun 12, 2013 15:04:42 GMT
Love the wedging system to keep the neckblock in place! Keith Good innit The 6mm carbon fibre tubes are then glued in using epoxy. The sides are also glued to the tail block at the same time using fish glue – just to prove that men can multi-task too :  The ebony porthole ring is glued to the ebony backing plate using hot hide glue:  The centre of the porthole is then routed out:  |
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Post by Mike Floorstand on Jun 12, 2013 20:17:25 GMT
I'm enjoying this thread Dave! Noticed you cut the soundport before moulding the bass side on this, whereas on Colin's Samhain build on your website you cut it afterwards, is there a technical reason for that are just trying different approaches? |
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Post by davewhite on Jun 12, 2013 21:01:59 GMT
Joe, Glad you are enjoying it. The "portholes" that I do on my mandolins and also on the hollow arm of my harp guitars are circular and need a flat portion of side to glue on the porthole and backing plate. On Colin's "Samhain" and other guitars where the sound-ports natural position is on a curve of the side, this porthole technique doesn't work and so I free cut the soundport. Well it could be done but I'd need a lathe (or CNC machine) to cut the complex 3-D shape required. I have done "porthole" soundports on guitars where there is enough flat area to the side and did this on Leo's "Sybil Iúr" and Bernd's "Féileacán Gallchnó":    For the "porthole" construction the hole for the porthole needs to be routed out on the unbent side to allow enough room for the circle cutting jig I use to operate. For the free-cut soundport it is easiest to do on the completed body. |
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Had some interesting discussion with Dave over the weekend about octave mandolins (aka octave mandola).
. Here’s the mould to hold the rim-set . . .
