Feature Presentation

Posted in Acorn House on November 14, 2016 by acornhouseworkshop

A little interview/performance I did about my work.

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Necking

Posted in Acorn House on June 28, 2016 by acornhouseworkshop

There are many ways to create an instrument neck. My method will vary depending on what size neck I’m making, and what wood I have available. For the mandola, I went with a laminated neck in order to get the best grain orientation, and the maximum strength.

So I first glued up a curly maple—walnut—curly maple sandwich. Then, after the glue had well dried, I cut and faired the headstock angle. I don’t do any other cuts at this point, in order to make the next steps that much easier. I leave it long on both ends until the truss rod is installed. I will size it according to the scale length.

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With the channel for the truss rod cut at the table saw, I also rout out channels for some carbon fiber reinforcing strips; truly a belt and suspenders approach. Then I can install both the truss rod and CF strips. The truss rod gets a strip of walnut glued in over it, encasing it in the wood.

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Now the neck can be rough sawn at the band saw, and the V-joint tenon cut at the heel on the table saw. With those cuts made, I use some of the offcuts to make two wings to make the headstock wider.

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While the glue is drying, I go to work cutting the inlay from a mother of pearl blank and inlaying it into the headstock overlay. This is then glued to the headstock’s face.

The back of the headstock now gets sanded to thickness, leaving a little curve at the juncture of the neck for forming a volute, giving a little more wood where the truss rod pocket is. On this I glue a walnut veneer, providing yet more strength. The whole headstock now gets routed following the template.

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With all the wood on, now is the time to start actually carving the neck. I start with the volute, getting it to a pleasing curve.

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Then its just a matter of working the wood down the neck until it feels right; rechecking for any bumps or off spots. The curly maple is a little less friendly than mahogany to work on, but you just have to keep on whittling away with knife, spokeshave, rasp, file, sandpaper, and scraper. Whatever works best, going from coarser to finer.

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After fitting and attaching the neck joint and gluing on the fingerboard (down the road) the final sanding to a glass smooth surface will be done.

Hm… a glass neck. I wonder how that would work?…..

Arch-villain

Posted in Acorn House on May 31, 2016 by acornhouseworkshop

One of the most intimidating task in making a mandola, mandolin, or really any instrument with a carved arched top, is taking a solid piece of wood, and carving the convex top and a concave back to match. I start with a bookmatched wedge of spruce, Adirondack in this case, and, after flattening the bottom, I mark out the rough contours and use a router to hog off a good part of the wood.

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This gives me a good platform to start carving, and save me a lot of grunt work. Next, I break out my large(ish) instrument makers plane. These little hand planes, also called thumb planes, were first develop for violin makers, but when archtop guitars and mandolins started being mad, they found another, albeit very similar, group of users. With the thumb plane, I start to connect the terraces into a smooth arch.

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Until, finally, I have an approximation of the final contour, still a little rough, though; creating a nice pile of hamster bedding in the process.

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At this point, its time to refine the curves, and make sure I’m getting the arcs I want. So, I make some cross section templates at important points, like the bridge, and where the soundholes start and end, as well as down the middle. Since my last mando build, I’ve found that they are much easier to use if they are solid, so, instead of just using stiff poster board, I transferred them onto wood.. Plus they’ll be ready to go for any future mandola builds. They won’t go tight to my curves until the recurve is finished (which I won’t do until much later), but I can still see how much I match the ideal by looking for a consistent gap.

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With the rough arches planed, now I turn to my two tiny block planes, to smooth out the curves, removing the mark of the curved bottom thumb plane.

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Next, come the double curved planes to start working on the transition to the recurve.

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Scrapers step in to help smooth out those planes’ marks.

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Finally, an orbital sander gives a final smoothing of all tool marks, and blends the surface into one.

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To get the inside to match the outer curves, I set up a jig at the drill press that will register of the newly created top surface, and drill down to within 1/4″ of the top. This gives me an indication of when to stop carving, at least for the rough out.

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Then, a gouge hogs off the bulk of the wood, before the thumb plane again steps in to plane down until the drill bit holes disappear. The I know I’m 1/4″ from the outer surface, and I can begin more refined planing, as before, with the goal to have the thickest part where the bridge will rest, going thinner as it approaches the rim. The thinnest part will be at the recurve, which may be as thin as 3/32″. That allows the mandola’s top to react to the strings’ vibrations and transfer the maximum amount of sound; its what makes a “lively” instrument.

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The process goes as before, although I can’t use the flat bottomed block planes this time on the concave surface. A finish sanding and we’re ready to cut the f-holes and brace the top, before gluing it to the sides.

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I definitely need to get a padded glove for my planing hand before working on the maple back.

Bend to my will

Posted in Acorn House on May 15, 2016 by acornhouseworkshop

I do all of my bending on a heated pipe, in the traditional way. Of course, that means sometimes, when dealing with more figured wood, there are some casualties. Not all wood wants to cooperate.

I’m currently working on a mandola build (a mandola is the next size up from a mandolin, similar to a viola vs. a violin.) The back and sides will be curly maple. The wood that I had acquired was big leaf maple, a west coast variety that is often highly figured. But, sometimes those curls are the worst parts to try to bend, especially when trying to do a tighter bend. So it was with the side stock I had. I started with the tight curve towards the head, and as soon as I started to get get close to the diameter I needed, a seam started to open up, right at a curl. I had extra length so I tried again, and again, and again. Same story. On the last one, I thought it wasn’t too bad and finished all of the other curves and clamped it into the form. After a couple of days I checked on it. Sure enough, the last time through that tight radius, the curl had started to split. Also, the more gentle curves were not flowing; the wood just didn’t want to bend. Looking closely, I could see that the piece had too much runout — the grain didn’t go parallel to the board, but rather at an almost 30° angle, which was where the splits were following.

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As pretty as the wood was, it was never going to form a nice curved mandola rib, no matter how I cajoled it or tried to force it. It was too set in its ways.

So, I looked through my supplies and picked out another board of curly maple; milled it up, thicknessed it, and got the pipe hot, ready to bend. This time, as I worked on the tight curve, it flowed like butter, easily curving into shape. Both sides were bent and clamped into the form in no time.

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This wood was a lot more flexible and open to reason; and a lot more useable.

 

Kinda like some people.

Getting some curves

Posted in Acorn House on June 4, 2015 by acornhouseworkshop

 It’s been awhile since my last post, but that doesn’t mean I’ve not been busy. So, a little catch up (but not catsup) on my current project is on order.

I am working on a commission for an A5 style mandolin. The A5 style (and it’s more ornate F5 sibling) were originally developed in the Gibson factory by Lloyd Loar. They have carved tops and backs and f-holes rather than oval holes and flat or canted tops and backs of earlier mandolins. I am using curly maple for the back, neck, and sides, and a very nice, aged, Sitka spruce set from Orcas Island Tonewoods for the top.

With very curly maple, it’s always a bit of a worry when bending the sides on the hot pipe; the structure of the curls make them more prone to breaking. But, I trusted my technique and approached the task with guns ablazing (which is definitely not the right technique, as it leaves bullet holes to fill later on.) I did have an extra side milled from the stock I used, just in case. The first side bent easily, no problems. I got it clamped up in the mold and grabbed the second side. Of course it snapped soon into the process. Sigh. While I did have an extra to use, if that snapped I’d have to start from the beginning, since a different stock wouldn’t have the same curl pattern. Luckily, the third side proved as malleable as the first, and it joined it’s brother (sister?) in the mold.

After allowing to dry and set, a headblock and heelblock were made from some mahogany, following the curves of the mold. Then the two sides were trimmed at the ends and glued to the two blocks in the mold. The rim assembly was done.

Now the real fun begins. The thing about a carved top is that it is just that, carved. So, after jointing and glueing the spruce for the top, I traced the outline of the rim assembly onto the spruce and added some contour lines. These contour lines will be used to rout out the wood to rough depth; each line indicating an increasingly lower depth.  

This routing saves a lot of time by hogging away a lot of wood.   

Then, with carving gouges, curved planes, scrapers, sandpaper, and a lot of effort, the inside of the top is shaped to the required concave form, checking against the plan’s templates many times along the way.  From this inside shape, the outside curves will be gauged.

  To carve the outside of the top, a jig helps measure the depths of holes drilled, giving a rough (very rough as you can see) mirror of the inside.
  By first carving down to the bottom of the drill holes (using, again, gouges, planes, scrapers, and sandpaper) a rough thickness is attained; which is then refined to the desired finished thicknesses.  

After many (oh so many!) shavings the refined top is neared. Then more checking with templates and thickness gauges, and more shavings; then more…well, you get the idea. Finally it’s at a point to go on to the next step.

  

The placement of the f-holes is mapped out on the underside, and gauze is glued on as a reinforcement.

After this cures, the f-holes can be traced onto the top side, and holes drilled for the saw blades.  

Using a deep throat fret saw, the f-holes are sawn out and refined with files. (For the time being, they are left a little undersized. After the mandolin body is fully assembled, they will be enlarged to bring the air chamber into desired tuning.)  

Now, the top and sides can be positioned and joined; using as many clamps as you have on hand.  

The overhang is sanded flush to the sides, and a major step has been completed.  

Next, the neck will be carved and the glued to the body assembly. The back will go on after that step.
This could be a new fad in fitness training: mandolin top carving! A great way to work the upper body.

Finishing bits

Posted in Acorn House on July 31, 2014 by acornhouseworkshop

At finishing time, a number of things are happening near simultaneously. The bridge needs to be made, so that its position can be masked off before the finish goes on. It also has to be positioned correctly, no slip ups here, since its position won’t be able to change once the finish is on. (Not without taking the finish off and starting again!) While the fingerboard was slotted according to a certain scale length (the distance from the nut to the saddle,) in order for the ukulele to be perfectly in tune, a small amount has to be added, to compensate for the stretching of the string as they’re pressed down on the frets. In the case of an ukulele, this is about 1/16″.

Here is the bridge after masking and after finishing. (Notice the difference between the finished and the unfinished koa. Now it has truly become a “golden child!”

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Now, there are more choices when it comes to ukulele bridges; many use a tie-block bridge like that found on a classical guitar (just a little smaller!) After all, the ukulele is very similar to a classical in construction and playing. However, I decided to go with a more traditional ukulele bridge to keep with its Hawaiian heritage. (Actually, the ukulele originally evolved from a Portuguese instrument, brought over during the days of exploration. But, it has since become Hawaii’s national instrument and heritage.) With the traditional bridge, the strings (gut or nylon) are knotted at the ends and fit into a slot behind the saddle.

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The overall size of the bridge needs to be quite small, after all, so it doesn’t dampen the soundboard too much.

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Note how the saddle is filed differently for the second string. This allows a more precise compensation for the different sized strings so it will play in tune perfectly.

The frets were leveled and crowned and polished. Tuners (again, traditional friction tuners, although improved modern ones) were installed. The nut and saddle were shaped and adjusted for a low action. And now, the first pics of the complete Kulakeiki. (The headstock is actually darker, that is just a bad light reflection. I will be taking it’s “glamour” shots for its own page at a later date.)

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Hmmm. I’ve done tiny instrument now, and huge ones. What to do next?

Only 3 Items per Fitting Room, Please!

Posted in Acorn House on July 23, 2014 by acornhouseworkshop

After doing the initial fitting, it was time to get the neck down to a little more hand friendly shape. Before I can do that, I want to get the fingerboard cut to size and bound, using some more of the bloodwood binding. In order to get the correct nut spacing and angles, the width of the binding has to be subtracted from the desired width of the neck. Then the fingerboard is cut on the table saw and the arc at the bottom shaped at the sander. The binding is glued on and, after curing, the fingerboard is surfaced on the bottom. Now it can be glued to the neck blank. (I’m glueing it at this stage, so that the water content in the glue doesn’t cause any warping, which sometimes occurs in a thinner neck blank. After the glue has fully cured, the neck blank can be rough sawn for thickness at the bandsaw. Then the width is routed using the fingerboard as a guide.

 

Then its time to break out the spokeshaves, rasps, and files and shape the neck and heel. Then, with the neck shaped, the final fitting of the dovetail can begin. I did need to add shims on the dovetail (next one, I shouldn’t try to fine tune the fit until AFTER the neck shaping is done,) but, with it loose, its perfect for dialing in the fit of the heel to the body.

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A final overall sanding to everything, and the neck can be glued to the body. With the dovetail joint carefully fitted (after a LOT of checking, tweaking, checking, tweaking, etc.) so that it tightens up just as its seated, it goes together very quickly. Heat the glue, brush it on, slide it together, two clamps, and you’re done!

 

Then, after making the bridge, and masking it off, I can begin the finishing. I began with a few coats of very thin shellac, sanding between coats. The gold color of the loa really comes out now.

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After sanding all of the shellac coats down with 400 grit sandpaper, and masking off the fingerboard, its time to put on the first finish coat of oil/varnish. Now the color just becomes deeper and richer. (I brought it inside to do the bulk of the drying to control the humidity a bit more than the garage. 90% humidity just isn’t good for finishing!)

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A few more coats, and it’ll be ready for the final assembly.

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