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Wednesday, October 7, 2015

The Luthier: Part I- Framing

For the last 14 years I have been a percussionist, playing mostly symphonic and swing with four years of the marching variety, but since moving down south I have been unable to find a musical home. Music has, for such a long portion of my life, been one of the constant creative outlooks, and now that it has a glaring absence, I decided it was time to learn an instrument that was a little less oppressive to neighbours than drums and bagpipes (haven't forgotten about those just yet!). 

Despite my love for the violin, and although I may someday explore that as well, I decided to pursue a more celtic design. Mandolins, although in the right setting very enjoyable to listen to, I prefer the deeper acoustic tones. Guitars are fine and well, and there is such a wealth of resources available to learning them, but again, I am after a different sound. Mandolas, the larger cousin of the mandolin, are perfect, but harder to find. And then it came to me. To me, the best way to understand an instrument is to first understand how it is made. So, without any knowledge of the luthier's beautiful trade, I decided to build an instrument on which to learn. Because I am doing it myself, I am free of the commercial constraints of availability and reasonability.

The design will be a sort of hybrid between a mandola and guitar- the body of the former and the fretboard of the latter. In theory, it will yield similar sounds to the mandola while holding to the technique of the guitar. A 'Mandolar' if you will.

First, I needed a frame. For hollow body instruments, the sides must be bent into the requisite shape. Following the pattern of an A body mandola, I glued together a bunch of wood hiding out in the laundry closet in a rough trapezoid. Because it will be under a bit of pressure during the bending process, it had to be rigid and roughly the thickness of the side height. Due to my lack of a steam bending mandrel, I decided to instead turn to the route of a steam box. When the wood is sufficiently pliable, it is clamped tightly into the shape of the frame where it will dry and conform to the inset bends and curves.

Being extremely rough cut, the frame needed a tremendous amount of work to reach its final shape. However, my workspace is limited to the size of a bath towel folded in two. Without a workshop to use, or even a space that I can be unconcerned with producing dust and shavings, everything must be carefully done by hand.

Smoothing out the large rounds was the easiest part. My trusty No 52 spokeshave left a clean, even surface that required minimal correction later.

Periodically, I checked the frame for square, which I assume is extremely important when bending the sides. Torsion in the thin sides would be difficult to correct later, and this frame will also be used in the assembly and gluing of the sides to the back.

For the tight inner radii, I had little other choice than to use chisels and gouges. The process was even slower than before, and by this point roughly a week elapsed since first gluing the frame together.

After all the sides were finished, smoothed and sanded, I drilled a few strategic holes in the frame to accept clamps. Combined with some outer blocks, this is what forces the steamed sides to shape.

6 holes later (one for each pair of inner curves, one for the bottom, and one for each of the middle of the large outer curves), it's onto the joint braces. I have no idea if there is a technical word for any of this, as again, I have no experience being a luthier.

These strips will be in the corners of each joint where the sides cannot be bent to be one continuous piece of wood. It will both reinforce the joint as a structural anchor for the tension that will inevitably still be in the wood after bending (based on the test bends I did, the final curvature was never perfectly tight enough, requiring the wood to be bent into place).

Because the frame is not quite deep enough, the ends of the braces hang over a bit, although they are still longer than the mandola sides and will be trimmed after assembly.

First, the width of the brace is cut, sized to the frame.

Then it's back to work with the plane. Each shape is made individually to account for the direction of the sweep. Note the two finished pieces whose ends you can see above the plane.

Gradually, the waste basked filled with layers of shavings, changing from tan to brown to purple and back again.

Those four little pieces were the easiest, but the inner corner was a bit less so. Compound curves met at a skew angle, which made the wood too shallow to accept the needed dimensions. So I split the wood and glued it together to doubled its thickness.

First is trimming the width. I could have just worked from one side, but the two sides were not perfectly aligned from gluing, so I split the difference.

Then with a number of chisels, I cut out the inner corner and checked for square.

Transcribing the shape squarely onto the frame was tricky, but it does not matter all that much. The frame will only be lightly holding the corner block for bending, and during assembly, I do not want it to be tight anyway. The tighter the fit, the more difficult it will be to remove after the sides are glued together.

Scribing the lines using a handy knife, cutting the grain on the faces and across the height of the sides. Unfortunately, as I struggled with throughout the entirety of building this frame, the wood grain changed directions with every piece that were glued together. It made a sort of plywood, which is great for the strength but awful for shaping.

Slow work. Should have cut the long lines with a saw, but still would not have been able to chip out the rest because of how it is glued...

And there we are. The fit is a bit sloppy on the corners, but as I mentioned, not necessarily a bad thing.

Now we turn to the first major piece to be used in the actual mandolar. This block is what reinforces the butt of the instrument and serves as an anchor for a strap. Because it is not a piece of scrap, I did not want to make nay errors here.

Same as with the others, the block gets inset into the frame, and the necessary curvature traced. When seen from above, the shape of the frame should be uninterrupted for all these extra blocks and braces.

Close, but the corners need to go.

To the block plane to ease the geometry.

This, two weeks later, is where I thought I was finally done with the frame. Wrong! I still needed to make all the reverse curvature clamping blocks.

Fortunately, most of them were easy outside curves.

Trimmed out of pieces cut from the original roughing of the frame, the seven pieces were conveniently the perfect height.

Rasps, saws, planes and chisels made decently fast work (still monotonously slow, mind you) of the first five. Those remaining two, however, were a bit more complex.

Due to the grain directions changing in the block, I had to make several cuts with the saw and chip out the ribs, finishing with files.

Aside from one errant cut, it was not bad. Doesn't need to be perfect, as this will merely be a pressure distributor so the clamp does not destroy the side wood.

Finally, the last piece is carved and fitted to the interior corner block from before.

And that's it! About a month of work with simple hand tools over the foot of my bed as a work bench, and the frame is done. This will (hopefully) be by far the most tedious part that has no real place to be showcased in the final instrument. Next up- bending the sides to shape.

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