The belly's on

The belly went on without any fuss, and I have now trimmed the overhang ready to start on the binding. I decided to use some of my new holly for this, so I have cut some thin strips on the bandsaw and used the drum sander to reduce then to 1.5mm thick (veneer, really).

Exciting wood

I always love getting hold of new bits of wood. I have just picked up some new pieces from Paul at Goulden Hardwoods. I've been planning my next instrument, and top of the list is a lute. I am going to have a go with yew ribs, and sycamore neck. Also in the selection is some lime to make the mould (the sycamore I used in the mandolin mould was a bit hard). The holly will be for inlays (it has a really nice figure against the pale background) and the walnut at the front is for the ribs of the next bowlback mandolin. Finally, the really big bit of walnut in the back looks like it might offer up a guitar back and sides or two (so it will be sitting in my workshop for some time yet!).

Meanwhile, I have glued the belly onto the bowlback mandolin. In the end I used titebond, and used plastic insulating tape to hold the belly in place while the glue sets.

Bowl and Belly

The belly is now pretty much completed. The two halves of the tail side of the belly were glued together and this forced the 'cant' angle to set and the belly to stiffen. I glued a reinforcing strip along the underside of the join - I think that this will also help with the accoustic properties of the belly by making it a bit stiffer without adding too much weight.

I used Extramite (formaldehyde urea) glue for this joint.

I tidied up the braces, and added the reinforcement piece at the neck end of the belly. I assume that this is to help support the fretboard, and I don't think that the belly here will add much to the sound.

Before the braces were cut to length I marked the position of the notches cut into bowl (three on each side and one at the tail end to accommodate the reinforcing strip.

Two of the side notches are shown in the third photo.

The final job for the day was lining the bowl with paper. As I understand it, this will help reinforce the rib joints, and will also make the inside of the instrument look a bit neater!

I puzzled over the choice of paper and glue, and asked Dave Hynd for a bit of advice. Dave has a fantastic website: Mandolin Luthier, with lots of really useful information.

He was very helpful, and I ended up using brown parcel paper and PVA glue (diluted a little with water).

The moisture in the glue might cause the ribs to shift a bit, but a couple of passes with a fine cabinet scraper should fix this when everything is stuck together and dry. I will probably apply a coat of clear varnish over the paper after I have stuck the label in.

Mistakes

I'm sure that everyone makes them, but here's my latest one. When I measured the tuning machines to find the correct spacing for the holes in the peghead I was 1mm too short. This was down to the metal plate being slightly bowed and I foolishly measured at the ends of the rollers and not at the base where they join the plate. I went ahead and drilled the first set of four holes before I realised my error and the final hole ended up 3mm out of position.

To fix the problem I glued a circular offcut of peghead veneer to the end of an 8mm wooden dowel and used superglue to fix it into the wrongly positioned hole. The pegheead veneer was left a little proud and scraped flat when the glue was set. The other end or the dowel was sawn flush with the rear (the endgrain will be hidden by the tuning machine plate).

Finally, I redrilled the holes (using a jig with the correct spacing), and the final result is not too bad. Most of the repair will be hidden by the tuning machine bushing, in any case. I made a better job of the second set on the left.

The Belly

Here is the rosette and pickguard inlaid into the belly. I made them quite thick, so there was a lot of scraping to get them flush with the belly wood. Sandpaper wasn't suitable as the ebony dust would stain the spruce wood.

The next job was cutting out the soundhole, and after that the more tricky task of cutting a wedge shaped slot into the part of the belly that slopes downwards. In retrospect, I probably should have done this before the two halves of the belly were glued together, but in the end I used a scalpel and a razor blade, and I was reasonably happy with the outcome.

The next stage was bending the front. I first made a groove in the back of the belly that went about two thirds of the way through (leaving a bit less than 1mm of wood). After a bit of experimenting I found it was best to put some water onto the belly at the join, and then apply heat to the front while bending. Once I had the required 15 degree angle I clamped it onto a wedge while it cooled.

The lines on the last photo show the position for two of the three braces.

Rosette

After thinking long and hard, I decided to make the rosette and the scratchplate out of macassar ebony to match the fretboard and peghead. I made an oval pattern on the computer, and sliced out bits to fit and glued them together with superglue. It was finished off with some black and white banding.

Fretboard

First of all, Happy New Year to anyone reading this post.

Over the holidays I managed to make some progress with the cittern. I have been working on the radiused fretboard which is made from a nice, black, ebony. Before I cut the slots I made a new slotting jig, with roller bearings for the saw blade, depth stops and an indexing system for the fret spacing. This worked well initially, but the saw was sticking badly in each slot beofe the correct depth was achieved. I eventually switched to finishing the slots by hand, but even then I had to use candle wax on the saw blade (which I wasn't happy about).

In the photo, the fretboard is only clamped to the neck - it is located in place by some tiny dowels (made from toothpicks) which will stop it slipping about when I glue it in place.

The bowlback has been fitted with its last side pieces as well as a macassar ebony peghead veneer which will match its fretboard (and probably pickguard too). I'm now ready to start the belly - this presnts some difficult challenges on account of the 'fold' - watch this space...

On with its neck!

In the end I did most of the neck shaping before I glued it onto the bowl - I just left the area around the joint over large and then shaped this after the glue had set.

I used Araldite for the neck joint and also added a dowel for additional strength. I did most of the shaping with a sanding drum on my multitool (running at a fairly low speed to avoid scorching).

Bowlback neck

Here is the start of the neck. It's made from maple, and is formed from a central core and some 'wings' glued on. The recessed section underneath where the fretboard will sit is to accomodate an extension of the belly. I noticed this feature in the mandolin I took to pieces and I presume that it will add strength to the neck - body joint.

I have been wondering whether to glue it on to the bowl and then do the shaping, or shape it first - I will probably go for the first option.

Status Update

I managed to 'rescue' the situation with the end cap of the bowlback mandolin by adding some edge pieces cut from some of the spare rib material. I bent these to fit on the iron (they needed to be bent in three dimensions!) and stuck them on with superglue. I broke lots of my early attempts. There were still a few gaps left so I filled these with araldite mixed with walnut wood dust. The result is OK, but not my finest work! All that because of a flawed design! I have now started on the neck.

I have also been making a bit of progress with the cittern. I fitted the bindings, and I think these look great (which is just as well as I want to sell this one when it's finished). I'm now starting on the fretboard.

A dog's breakfast

I have made a right dog's breakfast of the end cap... On the first attempt I made the end cap too thick (a little under 3mm). I could not get this to bend successfully (even after wetting the surface) so I made a new one, this time about 1.7mm thick. This bent well, but fitting it to the mandolin bowl was a nightmare. The problem stems from the fact that wood (or paper or anything non-rubbery) won't bend in two directions at the same time. This means that the surface to which the end cap gets glued has to curve like a cylinder, and not like the surface of a sphere! So the basic problem lies in the design of the mould (I will have to fix that for the next one). With a lot of clamps, too much glue, and quite a lot of swearing I did manage to get the end cap fitted - after a fasion. Once the glue is dry I will have to add some decorative bits to hide the gaps. Oh well, it's all part of the learning process.

Bowl complete

Well, the basic shape of the bowl is now complete and here it is, removed from the mould. Once I'm sure that I won't be needing to put it back onto the mould I will chisel off the extra bit that was glued to the inside front cap (with the screw holes in it). The next step it to fit the end cap which wraps around the front of the bowl. When this is done I will line the inside of the bowl with paper - I'm thinking of using tissue paper and a dark coloured cellulose dope (the stuff used to cover the wings of model aeroplanes).

Bowl Progress

I've just fitted the second of the two wide ribs that complete the bowl. These were much trickier than the narrow ones and even when bent as accurately as possible they seemed to twist out of shape when gluing them up - I think the the mould is at fault here and that the next mould needs to have this section at exactly right angles to the top. I will also add a removable section to the mould to give something to push against when fitting these last two ribs.

Luckily, I managed to get the untidy part of the joint to be at the front of the bowl where it will be covered by the end cap (which I'm going to fit next).

The thirteenth rib

We had a trip away last weekend, so there was no chance to spend any time in the workshop. However, this weekend I managed to do another couple of ribs on the bowlback. I am definitely getting better at the process, but I still find it tricky. The key seems to be getting a really accurate shape when bending the ribs, and then marking the sides to be shaped carefully with a thin flexible metal straight edge fixed to the bent rib with small spring clamps.

The other thing is the glue... I have taken to squeezing some Titebond onto a piece of polythene and then folding this in half. I then drag the thin stringer through the glue inside the polythene to coat both sides of it at once and then trap this glue soaked strip between the existing bowl and the new rib before hammering in the tacks.

Four more ribs to go!

Rib seven

The bowlback is making good progress, and I added ribs six and seven this weekend. My wife spotted it in my workshop last week and reckoned that it looked like a 'demented armadillo' so at least it has a name!

The mould needs some improvements for next time:

1.The end cramps slip off too easily, for example when I hammer in a tack, so I will have to devise a way to fix the head of the cramp inside the mould.

2. I think it would be better to shape the mould with flattened areas to acommodate the ribs (it is rounded in cross section at the moment).

3. my gluing up technique with Titebond is messy, so I could use a brush, or maybe try the hot melt hide glue stuff.

Meanwhile, I have put together a device to make the cutting of binding channels a bit easier. It is inspired by the one available from Stew Mac, which I think is really expensive! Mine was made from bits and pieces I already had, and seemed to work well on the cittern. I was especially pleased with the counterweight, which is the head of an old club hammer connected by wire over a cotton reel.

Bowlback - rib number two

I have now started on the ribs for the bowlback.

After bending the middle one to shape (dry) on the iron, I glued down the tip and the tail, and when the glue was set I shaped it with a chisel and then a file.

The next day I prepared a 'stringer' by bending a strip of sycamore veneer, and then bent the second rib to shape. After a bit of shaping (again with a chisel and a file) of one side of the second rib, this could be fitted in a fairly snug way to the first one with hand pressure. The stringer and the second rib were then glued into place (and at the tip and tail) and held in place with some carpet tacks and a rubber lugage 'bungee' while the glue set.

The next step will be to fit the third rib (on the opposite side to number two), and then to shape the outer edges of these ready for ribs four and five.

There are seventeen ribs in all, and two wider pieces at the top, as well as an end 'cap' and decorative side pieces. This will therefore take ages !

A few observations - First, I am using titebond glue, but I wonder if hide glue would be better. Secondly it's going to take a lot of practice to get any good at this and; Thirdly, I notice from the photos that I am a really untidy worker!

Stringers

I thought that I'd have a go at making a stringer today (the thin strips of pale wood between each of the ribs). I expected to find these quite tricky to make, but the process was surprisingly simple!

First I used a hacksaw to cut a groove in the top of my bending iron (actually the extension piece). The slot was deeper at the edges than the middle to make it curved at the bottom. I then cut some 3.5mm strips from a sheet of sycamore veneer (0.6mm thick) and dragged these through the slot once the bending iron was hot. As long as I worked with short movements, holding onto the strip as close to the iron as possible, it was straightforward to shape curves with different radii. Two of these practice bits are also shown in the photo. A light coating of moisture (applied with finger and thumb) speeded up the bending a bit.

When I make the stringers 'for real' I will probably prepare a set of strips and bend them as I need them.

Neck and ribs

It's always a big moment when the label gets glued in. I have counted back and decided that this cittern is instrument number eight, so I've added this as a serial number - this is probably a bit pretentious. The belly is already made, the braces are trimmed and I'm ready to glue it on.

Meanwhile, I have taken a piece of walnut and started to prepae the ribs for the bowlback. I cut 4.5mm slices with my bandsaw (with a fresh blade fitted) and then reduced them to a thickness of 2.7mm with my drum sander. Out of the 24 bits, a few are sapwood and very plain, but the rest have a nice dark colour and some attractive grain.

Mould

Here is the new mould, with the shaping finished, next to the original.

Bowlback mould

The mould is underway. Here are the first two bits (sycamore) in place - the rest builds up on either side and then gets carved to shape. I've just started the carving process and I'm remembering just how hard sycamore is! This step is going to take a while...