Wednesday, April 30, 2008

THE HEEL CAP

DESIGN CONSIDERATIONS
I wanted to make the heel cap into a little appointment that would tie in with the overall color scheme of the wood parts and ornamentation and thus go a little further than just letting it be a little bumper to protect the softer heel/neck.

In this case I chose to echo the look of the binding and purflings, making cap itself the same thickness as the bindings with a maple/bubinga/maple veneer sandwich underneath that matched the purfling. At the very bottom a slice of bubinga veneer was added to create a contrast between the heel itself and the maple/bubinga/maple veneer sandwich. Of course this is not a new concept nor is it an exceptional idea in any way, but there you have it.

Another design element I had to consider was how to deal with the nonparallel planes of the stacked heel and the domed back. In order not to creating a slight change of angle where the cap meets the back, I figured I had two options:
  • To have the cap follow the doming of the back by way of sloping the heel step parallel to the tangent of the back and thereby creating a slight downwards angle towards the tip.
  • To follow the plane stacked heel, but tapering the cap in order for it to continue the tangent of the back.
I decided on the first one as I thought it would be the simples and cleanest looking. Yet another option could also be to make a thicker bottom veneer out of bubinga and then taper that, but I don't know how well that would have worked.

MAKING THE CAP
One good thing about resawing your own wood is that you inevitably end up with lots of scrap wood that is ideal for these purposes and thus I had a nice chunk of 3/4" bubinga that suited the bill perfectly.

I cut off a little piece 1 1/4"x1 3/4" and sliced a 3/16" thick cap off of that. From the leftover I fabricated a 1mm thick veneer that was to go on the bottom. Three similarly small sheets of veneer, two maple and one bubinga, were cut and it was all glued to a sandwich and trued further to a slightly oversized rectangular cap.

FITTING THE CAP
Next up was trimming the heel down to a step that allowed for the veneer sandwich of the heel cap to be aligned with the side purflings. This was done with a 1" chisel first in big chunks and then slowly doing thinner and thinner slivers as the worked progressed to it's final depth.

The binding was trimmed
flat over the heel. I didn't take any photographs of this but basically the slight curve in the area over the heel where the bindings meet was pared down to a flat. It wasn't really very much to come off but the curve was pronounced enough to make a nice butt joint with the heel cap impossible.

Using the shooting board, a slight bevel was planed on the back of the heel cap to accommodate for the angled heel that followed the curvature of the back. I didn't use any measuring for this but winged it by resting the end of the heel cap under some scrap binding, to lift it up at an angle. By trial and error I kept moving the binding in until the angle was steep enough to make a nice fit.

GLUING THE CAP
Once everything as aligned and fitted the heel cap
was cut on the bandsaw to a slighly oversized cap that was ready to be glued on. A la Cumpiano I used two cam-clamps for this. The clamps were positioned at a slight angle, so any sliding that could occur in the wet glue would be towards the body.

A note on the bandsaw operation. Getting my fingers this close to a running blade was not my favorite way to spend an evening and I only did it because the friendly photographer was very insistent. Next time I think I'll be using a coping saw or just chisel away at it once it is glued on.

CARVING AND TRIMMING THE CAP
After the glued had dried I pared the heel cap down, close to a final shape. The last bit will be taken off once I get to the final carving of the neck and heel.

For now the cap was shaped in facets as I did with the initial heel carving. First the sides were taken down to fit the width of the heel. Then I carved the tip to a flat. After these two reference planes were done a primary facet were cut, followed by two secondary facets. Last the facets were cleaned up to a smooth round curve that extended the shape of the heel.

The cap also had to be trimmed flush with the backplate. For this I used a block plane to get rid of the bulk of it and finished it off by scraping.


THE HEEL CAP COMPONENTS

GLUING THE HEEL CAP TOGETHER

PARING THE HEEL STEP TO PROPER HEIGHT

MEASURING HEEL STEP DEPTH

TRIMMING THE BACK OF THE CAP TO AN ANGLE

PRELIMINARY SHAPING

GLUING THE CAP ON

CARVING HEEL CAP WIDTH

FACETING THE CAP

PLANING HEEL CAP FLUSH TO BACK

THE FINISHED HEEL CAP

THE FINISHED HEEL CAP

THE FINISHED HEEL CAP

THE FINISHED HEEL CAP

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