Making "Ceithre"

"Ceithre"

 

I have a commission to make "Ceithre" - a Venezuelan Cuatro - with Lawson's Cypress top and Sapele back and sides. This is a new instrument for me and should be interesting and fun. Cuatro is four in Spanish and Ceithre is four in Gaelic. It will be made on a solera using a Spanish heel neck joint.

 

Last updated 18/12/2016.

 

Here are the plans.

As it's a new instrument for me I have to make a bending form and solera.

Here are most of the parts.

Time to make the reverse kerf linings. These are made Spanish Cedar. The strips have been cut and thicknessed and one edge rounded over. The kerfs are then cut on the bandsaw using this jig.

Here are the finished linings.

The scarfe joint is cut on the Spanish Cedar neck blank and glued up using hot hide glue in this jig.

The pieces for the stacked heel are then glued up using hot hide glue.

This is shaped and glued to the neck with hot hide glue to form the Spanish heel.

The Sapele sides are thicknessed.

I'm going to fit an Etimoe "porthole" soundport in the bass side just before the waist. First job is to cut a 35mm diameter hole in the side using a Forstner bit.

A Sapele blank fills this hole whilst the side is bent. An identical sized Etimoe blank was cut at the same time to form this part of the "porthole".

The sides are then bent one at a time in the Fox-style bender using a heating blanket. The wood is given a very light spritzing of water, wrapped in brown paper and then put in the "sandwich" of slat, wood in paper, slat, blanket, slat.

Here are the sides trimmed and in the solera.

The two parts of the Etimoe "porthole" are glued together using hot hide glue.

The inner porthole is then routed out.

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

The Lawson's Cypress top plates are initially thicknessed, jointed and glued using hot hide glue and the tent method.

The top is then thicknessed and cut close to the final shape. The rosette channel is routed out using the circle cutting jig.

Here's the result.

The rosette is carefully fitted and glued in using pva glue - it consists of inner and outer rings of bwb purfling around a central rope purfling ring.

The Etimoe golpeador is glued on to the top using hot hide glue in the go-bar deck, positioned in place with two 6mm drill bits.

The Lawson's Cypress soundhole re-enforcement is glued on in the go-bar deck using hot hide glue.

The soundhole is then routed out using the circle cutter jig.

Here's the result.

Here's the top after trimming closer to the final shape.

The channels for the two carbon fibre truss rods are routed.

These are then glued in using fish glue with Spanish Cedar caps.

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

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

The first Lawson's Cypress A Frame brace is glued on in the go-bar deck using hot hide glue.

Then the second one is glued on.

The Sapele back plates are initially thicknessed, jointed and glued using hot hide glue and the tent method.

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

The rebated holes for the tuner inserts are then reamed.

The neck is cut close to the final width and the side slots are then cut. The sides will be held in place by two wedges.

Then the Etimoe ebony end graft is glued to the lime tailblock using hot hide glue.

The sides are then glued to the tail-block with bwb purfling strips in between the sides and end graft using hot hide glue.

Initial carving of the neck is now done as it will be easier than with the neck attached. Fine tuning will come when the fingerboard is attached.

The top of the "headblock" is rebated to the depth of the top and slots cut to take the outer two fan braces.

Here's how the top fits.

The sides and neck are joined in the Solera by glueing in the wedges with hot hide glue.

Next the 12mm hole for the K&K pickup is drilled in the end-block.

The main transverse brace is profiled to a 13' radius, notched to fit over the A Frame braces and then glued on using hot hide glue.

The second ladder brace is glued on in the same manner.

Then the inner two fan braces are glued on.

The top two Lawson's Cypress ladder braces are profiled to a 13' radius and then glued on the back using hot hide glue.

Then the bottom ladder brace is glued on.

The sides are profiled for the top's curvature and the linings are glued in using fish glue.

The sides are profiled for the back's curvature and the linings are glued in using fish glue.

The Spanish cedar side braces are notched into the linings and glued in using hot hide glue.

The braces are carved and the top "voiced". Then the top is signed and dated.

Here's the "voiced" top.

The linings are notched to accept the brace ends and the top is glued to the rim-set using fish glue.

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

The Sapele back strips are glued in using hot hide glue.

The K&K Twin Spot transducers are glued onto the top using superglue gel and the endpin fitted.

A bridge clamping caul is made that spans the transducers and fan braces.

The label is signed and glued onto the back.

The linings are notched to accept the brace ends and the back is glued to the rim-set using fish glue. The neck has been set at the correct angle in the jig.

Unfortunately the top suffered damage in the process of glueing on the back that meant a new top had to be made. Here's the new top signed and dated after the "voicing" process.

Here's the new top bracing.

The new top is glued to the rim-set using fish glue after fitting a new K&K pickup.

The Etimoe bindings have the b/w/b side purflings glued to them are taped together.

They are then bent to shape in the Fox-style bender.

The back 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.

Then the top binding channels were cut using the same process.

Next the router is set to cut the back purfling channels and these are routed out.

The top purfling channels are routed out - the golpeador area is left uncut.

Then the back bindings and purflings are glued in using fish glue.

The top purflings are then glued in using fish glue.

The top bindings are then glued on using fish glue.

When the glue is dry the bindings and purflings are scraped and sanded flush. Here's the result.

The Macassar ebony fingerboard is marked for the frets and the slots cut in this jig.

The fingerboard is tapered and the Macassar ebony bindings with b/w/b/ purflings are then glued on using fish glue.

The side dot markers are then installed.

The fingerboard is then glued to the neck using fish glue.

The fingerboard is radiused.

Then the frets are pressed in.

Here's the result.

The Etimoe heel cap with b/w/b veneers to match the side purflings is then glued on using hot hide glue.

The 3mm wide saddle slot is routed in the English Walnut bridge blank with this jig.

Here's the result.

Another 3mm slot is routed at the front edge of the tie block.

Here's the result.

A piece of Macassar Ebony is then glued into this slot. This hard wood cap will stop the strings digging in to the tail block.

A piece of Macassar Ebony is thicknessed, marked for the 12 string holes and drilled with a 2mm brad point bit. This will be the template for drilling the tie block string holes and act as the back edge cap.

The Macassar Ebony template is glued onto the bridge tie block.

The string holes drilled through with the 2mm brad point bit.

A 5mm wide slot is then routed out just in front of the Macassar Ebony insert.

Here's the result.

The two wings are then rough cut and the bridge is shaped and ramped. A Macassar Ebony cap is then glued on the tie-block.

The bridge is carefully positioned on the top and masking tape used to form a "nest". Two 2mm holes are drilled in the saddle slot through the top so that parts of cocktail sticks can be super glued in to hold the bridge in the correct position whilst gluing.

Like so.

Here's the bridge positioned with the glued in cocktail sticks.

The neck carving is then completed.

Next the pores in the Sapele 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 Sapele and egg white that is pushed into the pores - the albumin in the egg white acts as a binder. When dry the body is sanded with 240 grit paper.

The back, sides, neck and Golpeaor will have a pre-catalysed lacquer finish and this is sprayed on. The top will be finished later with Liberon finishing oil.

Back view.

Then the bridge is glued on using hot hide glue.

Here’s the final result after the top has been finished with Liberon finishing oil; the tuners, nut, saddle, strap pin and strings have been fitted and the playing action set up. Here’s the finished cuatro.

A back view.