You will either choose to free-build the guitar based on the 2D full scale design plan you may have, or have a 3D mould of the design. I chose to have a mould, as I felt it might be handy to hold the guitar in it and to ensure the sides were bent correctly vertically at 90 degrees, as well as correct horizontally. Either you can buy a mould of the design you've chosen (usually from the same supplier), or make a mould yourself. It should be noted that the mould is only a guide - it shouldn't be used to help the guitar stay in the correct shape and design after you've bent the sides, as then you're stressing the wood into the design which may introduce problems of its own later on; it should sit freely in the mould after the wood has been bent. I made a mould from 4 thick sheet slabs of MDF glued together and drew my design on to it. At this stage I was on the course and had access to a bandsaw to cut the design out. Otherwise I would probably have bought a mould or free bend against the flat design.
Sides
I started with the sides as I wanted to get the shape sorted out first off. For my design, the thickness of the wood was to be around 2mm all round for a good sound/structural integrity ratio. Consult your book or design for your own measurements. To achieve this takes a lot of hard work and time. The wood will be uneven straight from the supplier and it can be very boring planing the wood to correct thickness, but you'll be doing a lot of this during the build, so get used it! You need a good plane and sharp blades, plus you'll also need a caliper which has a throat depth long enough to measure the thickness throughout all points of the wood, to ensure an even thickness and tone across the wood. Unfortunately, these calipers are not cheap!
Use chalk to help you with the thickness - shade areas where they are too thick so you know where to concentrate the planing and keep checking with the caliper as you go - more often when you get near to the 2mm. Be careful of planing too much off - I went to about 2.2mm - 2.3mm depth, as later on you will be sanding and smoothing more off and will need some tolerance to work with
Once down to thickness, it was time to bend the wood. You will need a bending iron for this, or I have seen some articles on the net involving clever substitutes such as a metal heat pipe and a normal steam iron, should be able to find more about this with a quick google. When using the bending iron, I found it quite difficult initially. You have to keep the wood wet by keep wiping it down on both sides with a cloth and water as you bend. Bend on the smaller side of the iron in small degrees for the middle section, keep checking it against the mould. For the large bends, sorry to use a cliche but let the wood do the work - use the full length of the wood against the iron and you'll get a more even, rounded shape. Keep wiping down with water. Be patient, don't rush it or you will break the wood and have to get a new set of sides. Each side bit will overhang the centre line of the mould, which is fine, because you will cut and glue them evenly later. Label the pieces for left and right sides for easy reference (whilst they should be completely symmetrical and fit the mould perfectly either side, mine weren't exactly 100% - but it's part of the handmade nature of the build and acceptance of the limitations of your first attempt)
Fortunately, I managed to bend the wood ok without breakage - result!
My sides looked like this:
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| Wahay! First real achievement complete :-) |
You should have quarter-sawn pieces of wood for the front and back, so there is a nice book-matched grain on both pieces for each of the front and back. I joined each of the two pieces for the front and back before planing them. Not sure it matters if you plane them before or after, but I thought it would be better to join first and then plane as one large piece for the front and one large piece for the back, to ensure even consistency across the middle join for each. Just personal preference I guess. The idea here is to glue them together with absolutely no gap in the middle between the pieces across the full length of the wood. Sounds easy right? Wrong! It's actually very difficult - we're talking getting an absolutely perfect straight edge on each piece of wood using a hand tool (plane), to achieve a perfect join with not even 0.1mm of a gap - it can be time consuming to achieve this. I used a very long heavy plane to try to get a good straight edge on each piece of wood. Then I put the pieces together and checked carefully for any gaps along the length of the join. Best to have a lightbox or a very strong light and hold the pieces against the the light. It is very difficult to achieve a perfect join and again takes some time to get it right. Mark any gaps in the join on the wood with chalk so you know where to concentrate the plane, but I found using long strokes and cutting back each time if it was too much of a gap was the only way to get a good join, as otherwise you spend a lot of time over-correcting small dips or highs across the length of the wood.
When the back pieces had a good join with no gaps, I glued them together with Titebond (Original) glue - this is the best glue for this type of work in my opinion, as it has a 10 min pre-dry time to work with and can wipe it off with a bit of wet cloth fairly easily during this time. My clamping arrangement was like this, left overnight (using Klemsia Cam clamps). I had a large board with a solid wooden strip screwed into it. Then I put some wooden triangular splints between wooden strip and the clamps at one end, while the clamps put pressure on the sides of the wood at the other end:
I did the front pieces the same way. To give you an idea of how the sides look against the front (as well the rosette which is the only thing I decided not to make myself - it came from eBay from Ecuador), here is how it looks. Nothing glued together yet and the rosette to be glued in later, just all carefully placed in the picture :-). Those end blocks are mahogony which I also started shaping, but we'll see those glued in later in the blog:
