Making "Ceol Binn Mór"

"Ceol Binn Mór"

 

I'm making "Ceol Binn Mór" an octave mandolin with a European Spruce top and Colombian Rosewood back and sides for Keith Chesterton.

 


Based on the scale length Keith wanted the first step was to find an initial shape.


The next step was to find a suitable case which wasn't very easy. In the end this large bodied Irish Bouzouki case was the best option.


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.


Then the main components are assembled.


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 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.


Here's the bass side 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.


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.


The ebony "porthole" is then glued into the side using hot hide glue.


Here's the result.


Time to try out the fit of the rim in the case - snug.


The end graft channel is cut and the Macassar ebony end graft flanked by black/ pear/ black purfling glued in using hot hide glue.


The back is initially thicknessed, jointed and glued up using hot hide glue and the tent method.


The top is initially thicknessed, jointed and glued up using hot hide glue and the tent method.


The Colombian Rosewood central rosette ring is cut from a back off-cut using the circle cutting jig . . .


. . . with this result.


Next after applying a shellac wash coat the rosette channel is routed out of the top.


The central Colombian Rosewood ring flanked by black/pear/black purfling is tested for fit and glued in using white pva glue.


The European Spruce soundhole patch is glued on using hot hide glue.


Then the soundhole is routed out . . .


. . . with this result.


The European spruce back X braces are profiled to a 10' radius and notched. The centre strip is notched and the first X brace glued on in the go-bar deck using hot hide glue . . .


. . . followed by the second.


The lower bout ladder brace is profiled to a 10' radius glued on using hot hide glue.


Next the A Frame braces are glued on using hot hide glue, treble side first . . .


. . . followed by the treble side. These braces are flat and the ladder braces will be arched.



The European Spruce main ladder brace is profiled to a 10' radius, notched to fit together with the A frame braces and then is glued on the top using hot-hide glue.



The ladder brace below the soundhole is treated in the same fashion.



The sides are profiled to match the back's curvature and the mahogany reverse-kerfed linings glued on using fish glue.



The sides are profiled to match the top's curvature and the mahogany reverse-kerfed linings glued on using fish glue.



Now for a scary bit. This instrument will have a K&K pickup fitted but due to the limited access through the small soundhole I decided to glue the transducers onto the top before it is glued to the sides and so to check fit the 12mm hole for the end pin was drilled now.



Phew.



Here's the K&K end-pin jack adjusted and test fitted - perfect.



The tailpiece will fit nicely above.



Then the mahogany side braces are notched into the linings and glued in using hot hide glue.



Here's the completed rim set.



The Colombian Rosewood X brace cap is glued on using hot-hide glue.



The braces are then carved and the back "voiced" - here's the result.



Notches are cut in the linings for the back brace ends and the back glued to the rim-set using fish glue.



European spruce caps are glued over the A frame braces - bass side . . .



. . . followed by the treble side.



Finally the last ladder brace is glued on using hot-hide glue.



Then the "voicing" process starts - the braces are profiled to give the top response I am looking for. When the top has been "voiced" to my satisfaction I sign and date it.



Here's the voiced top.



The Colombian Rosewood back centre strips are glued in using hot hide glue.



As access through the soundhole will be tight I decided to glue the label in before the top went on.



The K&K transducers are glued onto the underside of the top using superglue gel.



Notches are cut in the linings to fit the top's brace ends and the top is then glued to the rim-set using fish glue.



Next the neck scarfe joint is cut and glued on the mahogany neck blank using hot hide glue.



The truss rod slot is routed out.



The adjustable truss rod is glued in with a mahogany cap using fish glue.



The stacked heel is glued up using hot hide glue.



Then the slots for the two carbon-fibre rods are routed.



The carbon fibre rods with mahogany caps are glued in with fish glue and clamped while the glue dries.



The Colombian Rosewood headstock veneer is glued onto the top of the headstock using fish glue.



The Colombian Rosewood veneer is bent to the shape of the volute and glued on the rear of the headstock using fish glue.



The Colombian Rosewood bindings and black / pear/ black side purflings are taped together.



Then they are then bent using this jig.



Here's the result.



The headstock is then cut to shape and the tuner holes are drilled using this jig.



Here's the result.



The rebated holes for the tuner inserts are then reamed.



After a bit more shaping of the headstock the Rubner tuners are checked for fit.



Next the top binding channels are cut using the binding jig to the depth of the bindings plus side purflings. The channels are stopped just short of the end-graft. Purfling pieces are stuck using double-sided tape over the end-graft. The binding channel is then cut over the end graft with the jig riding on these so that the depth cut is just that of the binding. The end graft side purflings can then be mitred using a chisel.



The process is repeated on the back.



Next the top and purfling channel is cut . . .



. . . followed by the back.



Then the top bindings and purflings are then glued on using fish glue . . .



. . . then the back bindings and purflings.



Finally the side bindings and purflings next to the neck are fitted and glued in . . .



. . . followed by the back edge.



The bindings are then scraped and sanded flush in the Troji and the top is then cut for the floating fingerboard.



A slot for the threaded inserts is routed in the heel and then it is glued on to the neck shaft using hot hide glue.



The neck has had the fingerboard extension cut on the bandsaw and this is then tested for fit on the body at the correct angle and position and so that the heel cheeks fit the neck-block perfectly. The positions of the threaded inserts are then marked on the neck, the holes drilled and the inserts fitted.



The neck-block is routed to correct depth for the neck's fingerboard extension and the neck bolted on to check the fit.



I thought I'd have to move the case neck support back but the fit is perfect as it is.



Next some black/ pear/ black side purflings are glued onto the fretboard ebony bindings using fish glue.



Then the fret slots are marked on the ebony fretboard and cut with the fretsaw in this jig.



The fretboard is the tapered and the end cut to match the soundhole using the circle cutting jig.



With this result.



A piece of binding is bent to shape on the hot-pipe and then glued to the fingerboard using fish glue. The binding is ebony with black/pear/black purfling.



When the glue is dry the binding edges are trimmed flush and the rest of the fretboard bindings glued on using fish glue.



The 2mm holes for the white side dot markers are then drilled and the markers pressed in.



Next the fretboard is glued onto the neck using fish glue.



The neck is then carved to shape . . .



. . . finishing like this. More fine tuning later.



Then the fretboard radiused.



The neck is checked for fit on the body.



Looking more like an instrument.



Check that it still fits the case.



The heel is trimmed for the heel-cap and after contouring to meet the back. Holes are drilled in the neck heel for two 6mm carbon-fibre rods . . .



. . . which are then glued in using fish glue.



The Ebony heel-cap is glued on using hot hide glue.



Here's how it looks after sanding flush.



Then the Gold EVO fretwire is pressed in.



The African Blackwood bridge blank has the bottom sanded to match the top's curvature.



The bridge blank is then marked and slotted for the bone saddle.



The saddle blank is cut to final shape Then the sides of the bridge are shaped and the bone saddle is fitted. Here's the fretted neck fitted with the bridge placed on the top.



Next the pores in the Colombian Rosewood back and sides are filled using egg white. Small pieces of 240 grit sandpaper are dipped in egg white and rubbed on the body creating a slurry of Colombian Rosewood and egg white that is pushed into the pores - the albumin in the egg white acts as a binder.



Let us spray. Back . . .



. . . and front.



The neck is sprayed too.



Initial setup involves fitting the tuners to the neck and shaping the nut . . .



. . . fitting the bridge tailpiece. The strings are fitted with slots cut in the nut and saddle and the action tweaked and set up.



Then the strap button is put on the treble side into the neck block.



Here's how CBM looks.



The neck felt a little too "chunky" in the hand so it's out with the scraper and some fine tuning.



Here's an adapted truss rod adjuster and a green baize backed piece of Colombian Rosewood to put under the tailpiece when changing strings.



I made and added another compartment to the top of the case.



Here it is open.



Here's the finished CBM. Front view.



Back view.



End view.