Sunday, February 22, 2015

Mandocello Soundboard Part I

I've just started carving the soundboard for Jonathan’s mandocello and here’s a description of the process so far.
Carved top soundboards come in the shape of chunky wedges and the first thing is to plane one surface of each piece completely flat.
With one flat surface, the join can then be tackled, however before I started to shoot the joint, I cut two slices of the spruce away, to use later as braces.
The join in a carved top soundboard has to be perfect all the way through and it takes a lot of time and skill to achieve this when working solely with hand tools.
Once the joint has been glued, the back surface has to be trued-up and the ‘board taken down to the required thickness and then the shape can be cut out.
Now we look at the profile of the soundboard. After much thought, design and planning, the first wood is removed and this will be a flat area to which the fretboard will eventually be glued.
Then I use the Wagner Safe-T-planner! A tool not for the faint-hearted, but very effective at generating a rebate around the edge of the soundboard. 
The rebate gives you a target to aim for once you start shaping the profile. First I like to work along the centre line and all of the shaping is done with a selection of planes. 
Wood is gradually taken away until the profile fits the template. 
With this profile shaped, I then start working at 90 degrees to the centre line.
More soon……………..

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Tuesday, February 17, 2015

Bending iron

The bending iron is an essential piece of a luthier’s kit. My well-loved one, comes from Touchstone Tonewoods and its irregular oval shape will cope with most curves that you’ll encounter.
So, I’ve just completed bending the solid linings for Jonathan’s mandocello. There are 8 separate pieces that are bent and then glued in place to create the instrument’s rim. These linings are made from sapele which bends with relative ease.
On the other hand, I’ve also just bent the sides for Alex’s twin-point mandolin; these are cocobolo and it’s probably one of the trickiest woods you’ll ever work with.
With any sides, you have to plan which way you are going to bend them so that the book-matched grain pattern works out. This is doubly important with my twin-point design, as half-way through the bending process I cut the sides in two (you’ll see what I mean in a moment).
I soak my cocobolo sides for about 30 minutes in water with fabric conditioner added; this can help to make stubborn wood a bit more pliable!
For this particular type of wood the bending iron has to be really hot. In general, as you touch the damp wood against the hot iron, the moisture instantaneously turns to steam,thus making the wood pliable. With cocobolo, its resin boils and comes to the surface and this too makes the wood pliable. I find that cocobolo will not bend until the resin boils. And again, unlike other woods, the resin seems to retain the heat in the wood, so unless you cool it down quickly by quenching it in water, the bend doesn’t stay in place.
Once the sides have been bent they look more like victims of a thermo-nuclear attack rather than the product of the luthiers’ gentle art! You can see the resin’s effect on both the sides and the bending iron…………
In the past, I’ve cleaned up with a cabinet scraper and fine abrasive paper, but it’s much easier (albeit messier!) to use wire wool and meths!
With the sides clean, the supporting blocks for the points can be glued on; but that’s another story!


Saturday, February 07, 2015

In the white?

You may have noticed that I often use the term, “In the white.” This is a term borrowed from violin making and refers to the instrument (which is made from white woods i.e. maple and spruce) before the typical reddish-brown varnish is applied.
This week saw the construction of Mark’s left-handed mandolin completed and it strung up in the white. I thought that I’d run through that process for you. At the top of the page is Mark's mandolin freshly sanded and in the white!
The first task is to fit the bridge blank to the curve of the soundboard. Once it’s been roughly shaped at the bench, the final fitting is done on the soundboard itself, with an abrasive paper. To ensure as good a fit as possible- the white pencil marks highlight which areas aren’t making contact.
Finally I like to use a feeler gauge to make sure there aren’t any gaps.

Once the base is fitting, the rest of the bridge can be shaped. The saddle is notched for the strings and shaped roughly for the intonation. With so many mandolins under my belt, I pretty much know how much compensation the strings need.
Before the tuners are fitted, it’s wise to seal the back of the head and put on a layer of masking tape. You’ll find that all brand new tuners have a lubricant put on by the manufacturer and unless the bare wood is protected, that lubricant will leach into the wood and stain it.
Below is the tailpiece that I’ve made and that has to be fitted into position.
The bone nut has to be carefully marked out and the slots roughly cut to depth.
Double check, and then we’re ready to put some strings on………
The nut’s slots are then carefully filed to the final depth; I use a feeler gauge between the underside of the string and the top of the first fret to measure the action.
Once I’m happy with the string height at the 1st fret, the action at the 12th fret can be adjusted by filing the saddle. With the strings at the correct height, the intonation can then tweaked by adjusting the point where the string breaks over the saddle.
The mandolin will now be left, under tension, for a few days and once it has settled down any fine tuning to the action or intonation can be done.
By the way, that's a day and half''s work!

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