Fitting the Back

Perhaps there's some aspect of successfully fitting the back that represents a significant milestone along the way to completing a guitar, or maybe it's just that I've repeated this part of the process enough times that I feel confident in the outcome and have come to enjoy the sensation and sound of the back braces clicking neatly into their pockets. Whatever the reason, it's a part of the build process I look forward to and derive great satisfaction from.

To reach this milestone - assuming that the dome of the back has already been sanded into the rims - I carefully align the back with the centres of the head and tail blocks, then mark the sides where the brace closest the the tail block will intersect them. I lay a steel rule across the guitar to join the corresponding marks, and pencil the line of the braces onto the top surface of the linings. 

As a precaution against chipping, I make a saw cut equal in depth to that of the brace end on the side of the pocket likely to be chipped by the clockwise rotation of the bit. I hope the right-hand photograph below shows this clearly.

With a spiral downcut bit mounted in the Dremel and carefully adjusted for depth, I rout the first pair of brace pockets, using the pencil lines as a guide. If the marks were placed accurately, the braces slip into place with just a hint of resistance. I check the fit of the back and widen the appropriate brace pocket to compensate for any misalignment. Once I'm happy with the fit and alignment, I can mark the next pair of brace pockets, confident that the alignment of the back will be more securely and accurately established as I proceed. When the four pairs of brace pockets have been prepared and the back fits perfectly, I can allow myself a moment of self-congratulation - before I remind myself that it's really only a minor triumph and that there's plenty of work ahead of me!

Cheers

Pete

The Modified OM

With the messy job of constructing a new bending form and outside mold finally out of the way, I've been able to make some progress on this guitar over the past week.

The walnut sides bent willingly, as they always do, and I was pleased to see that they conformed closely to the new mold, with the exception of some minor spring-back on one of the lower bouts. The spring-back was a useful reminder that it's advisable to subject the sides of any wood species to a couple of heating and cooling cycles before removing them from the bending form. I have to try hard to resist my innate impatience, and on this occasion I was a little premature in taking the second side out of the side bender, hopeful that such a compliant wood wouldn't require a second cycle. A quick touch-up on the electric bending iron soon had the side sitting obediently in the mold.

With the head block, tail block and kerfed linings glued to the sides, I'm better able to assess the new body shape. Needless to say, I'm greatly relieved that it matches my expectations, and that the time-consuming and incredibly dusty task of making yet another bending form and outside mold has been averted.

Noting the recent emergence of guitars referred to as "modified dreadnoughts", and lacking a more imaginative idea, it seems reasonable to dub my new guitar model the "modified OM"! 

Cheers

Pete

Kerfed Linings

I've fabricated kerfed lining strips from mahogany in the past, and while that's a popular and appropriate choice, on this guitar I was in the mood to use linings that closely match the colour of the spruce back braces. Spruce doesn't exactly grow on trees in my neck of the woods (puns intended), so I substituted Jelutong - a lightweight, light-coloured South East Asian hardwood species that serves this purpose well.

After bandsawing and thickness-sanding the strips, I set up a crude but effective jig on the bandsaw that helps me cut kerfs of a consistent spacing and depth. I leave a little more wood between the extremity of the cut and the opposite face of the lining than it seems is common with the off-the-shelf product, and the strips I prepare are a little more robust as a result. If there's any trade-off, it's that I feel the need to pre-bend the waist and upper bout portion of the linings on my bending iron prior to gluing them in place, more as an added precaution against breakage than out of any real necessity. 

A pet peeve, and the motivation for devoting a little time to preparing my own snap-resistant kerfed linings, is seeing an otherwise carefully crafted instrument whose linings are joined at some point, particularly when such joins are in plain view through the soundhole. Sacrilege!

Cheers
Pete

Headstock Binding Completed

Given the effort involved in binding a guitar headstock, I'm curious as to the upcharge a professional builder might reasonably apply, and whether a fee acceptable to the buyer could adequately compensate the builder!

Not only does my chosen headstock shape dictate that one of the sections of binding must conform to the tight curve at the extremity of the headstock, but mitering the individual binding pieces prior to gluing requires painstaking attention to detail. I know many builders cut these miters in-situ with a sharp chisel, but for better or worse, I choose to use my disc sander to do so prior to gluing them in place. As they're fitted dry in the first instance, I have the luxury of being able to discard any pieces whose miters don't meet my standards, with the need to start all over again acting as a strong incentive to get them right on the first attempt! With a light touch, and a patient approach that involves constantly checking for an exact fit, I'm able to produce tight fitting miters using this method.

Before I can think about mitres, however, I need to prepare the sections of ebony strip. The first step is to glue a black/natural purfling to one edge of the binding. I do so with the help of the clamps normally reserved for gluing kerfed linings, as the photo below shows. For the straight sections of binding, regular Titebond is adequate, but for those sections that will be bent into a curve - excluding the piece that fits the tightest curve and is treated differently - I like to use Titebond III, which is better able to withstand the heat involved in shaping the strips on my bending iron. Unless a piece of ebony is particularly reluctant to bend, I find they can usually be coaxed into shape without the use of water.

Gluing the black dyed and natural maple(?) purfling to the binding edge.

Maple veneer glued to what will become the inner face of the bindings.

Test fitting the first of the mitred corners, minus glue.

It goes without saying that accurately positioning the binding pieces as they're glued and taped into position, then tightly butting up the adjoining piece as it in turn is glued, contributes to an acceptable outcome. Call me strange, but when carrying out tasks like this that demand my close attention, I find that tidying up my work space before I begin unclutters my mind as well as my workbench - the Zen of guitar building in action perhaps!

One concession I make these days is to acknowledge that the tightly curved section can more easily be fabricated from two thin pieces of ebony rather than a single full width piece. As anyone who has attempted to bend ebony into a tight curve on a bending iron can attest, this makes life a lot easier. Once glued, scraped and sanded, it's almost impossible to detect that this section of binding has been laminated. To begin with, I run two pieces of ebony binding through the drum sander until they're half the desired binding width. The pieces can then be bent on the bending iron until they conform to the curve without the need to be forced into position. Once I'm happy with the fit, I laminate the two pieces of ebony, adding a layer of maple veneer to what will be the inner face as I do so.

Because this section of binding is fabricated from two layers of ebony, it's not possible to edge the piece with a strip of black and white purfling prior to bending as I did for the other pieces. Instead, I wait for the glue to dry, then clean up and glue one of the edges to a piece of black and white veneer sheet that has been prepared earlier. Once the glue has dried, the surplus veneer is trimmed from the inner and outer faces of the ebony strip, duplicating the look of the other binding pieces.

Completed headstock

Cheers

Pete 

Preparing the Headstock for Binding

I tell myself with each guitar I make that I'd save myself a lot of trouble if I left my headstocks unbound. Nevertheless, despite the fact that many of the top makers choose to omit this feature, and still manage to produce the kind of elegant, beautifully appointed instruments I aspire to build, the Macassar Ebony headstock overlay on my latest guitar was always destined to be bound in ebony, with a thin maple line inboard of the binding for the sake of contrast. Were I building guitars commercially, there would surely be an added incentive to leave the edge of the headstock overlay unadorned, perhaps offering the bound look only as an option - for an appropriate upcharge of course!

An earlier guitar featuring a bound headstock 

I use a laminate trimmer to cut the ledge for the binding. I select the appropriate bearing and make a test cut on a piece of scrap to confirm that the resulting rebate will match the width of my ebony bindings, with additional allowance for the maple veneer. Having done so, I adjust the depth of cut so that my first circuit of the headstock will cut the ledge just shy of the full depth required. My ancient Hitachi laminate trimmer isn't renowned for ease of vertical adjustment, so I repeat the process, increasing the depth of cut in tiny increments until the bit barely removes the last of the headstock material on the bottom of the ledge.

Routing the binding rebate

It's imperative when routing the ledge that I think carefully about the grain direction of the headstock overlay and the router bit's direction of rotation, with the potential for chipping and tearout always in mind. Proceeding carefully, I can climb-cut the most susceptible areas and end up with a clean, chip-free binding ledge.

The completed binding rebate.

I'll describe the fiddly process of preparing the individual binding pieces in my next post.

Cheers

Pete

Soundboard Braces

The soundboard braces have been shaped to a 25 foot radius and attached to the top, again using hot hide glue. I look forward now to profiling and carving them to their final dimensions, my goal being a light and lively soundboard. This is surely the most tactile and intuitive stage of the entire building process, when machinery and power tools lay temporarily silent, and finger planes, chisels and sandpaper take over.

A useful pointer to where I'm at on my quest to build a high quality instrument is that the soundboard bracing on each new guitar still seems to be lighter than that of the last. In many respects, I'm sure it's a good thing that my evolution as a guitar builder has been such a gradual process, with small incremental improvements marking what has been a long journey. Where soundboard bracing is concerned, I acknowledge that a bolder individual willing to take risks would equal my progress after far fewer guitars, but I'm happy nevertheless to plod along at my own cautious pace, learning as I go, improving my skills and gaining satisfaction from the improvements I see and hear after each guitar is completed.

With my weekends still dominated by household chores, my resolve to chip away at this guitar in spare moments through the week is certainly yielding results, as evidenced by my latest posts. Lurking in the background, however, is the need to construct bending forms and an outside mold to accommodate the modified body shape I've recently devised. Unfortunately, at some point soon, this necessity will act as a barrier to further progress and I'll be unable to avoid the task any longer! 

Cheers

Pete

A Guitar Back is Born.

A half hour here, an hour there, and before you know it, a guitar back has materialised. I've been making a concerted effort to make progress on this guitar after work throughout the week, when I would typically be less than productive where guitar building is concerned.

The back halves were joined with Titebond as usual, but I thought I'd attempt to use hot hide glue wherever else I can on this instrument. Apart from its great strength and resistance to creep, I enjoy the fact that it's so easy to clean up once the parts are joined and clamped. After allowing a short time for the squeeze-out to gel, most of it can be easily removed with a chisel-shaped scrap of spruce. A sponge dipped in the hot water from my glue pot, wrung almost dry, removes the remainder of the glue pretty effectively.

Attaching braces to the soundboard would seem to be a realistic goal for the week ahead. We'll see whether Murphy's Law allows me to achieve it!

Cheers

Pete