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.

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!”

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.

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

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.)

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

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.

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.

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!)

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

Continuing the skill-building theme, it was now time to work on another new technique: making a tapered dovetail joint. This is a very traditional method for joining the guitar body and neck that is still used by many today (although the bolted mortise and tenon joint has become very popular for many, too.) Its one drawback is that its a very finicky joint, requiring a lot of fine tuning to get it perfect; and if its not perfect, it won’t hold up. As an added degree of difficulty, I’ll be doing it all be hand, rather than using a router and jigs. Why? Well: 1. All of the pre made jigs are for a guitar, not for the smaller uke; 2. The router and I have issues, and can ruin the whole thing with just one slip; 3. I’m an idiot! No, not really; in fact doing it with saw and chisels takes no more time than making up jigs and routing, without the chance for any catastrophic slips. Also, jigs and routers work better with a flat shoulder, and  my uke has a sloped shoulder at the joint, to further complicate matters. First step is to layout the dovetail in the body. Next, I drilled a hole at the bottom of the V to provide an end pony for the saw to fit into. I hadn’t seen this technique in any method that I’d, so maybe this is an innovation, maybe not. Its something I’ve done when cutting sliding dovetails in a pedestal base, so its not totally unknown. Then, keeping both angled lines in sight, I made the first cut with one of my Japanese saws. After making the second cut on the other side, I drilled out a good amount of the waste. The, after chiseling out the bulk of the leftover waste, I used my miniature router plane to bring the bottom down to a clean, level, depth, cleaning up the sides and bottom, as needed, with chisels. Ta da!   That was the hard part. (Or so I thought.) After transferring the angles from the mortise to the neck blank, the mating tenon took five saw cuts and one chisel bow (at the bottom.) I made sure to leave the tenon a little on the large side so I would have enough material to fine tune the fit. Ah, the fine tuning. Therein lies the heart of the matter. As I said, the fit needs to be perfect, so that the center lines of the body and neck match, the neck angle lines up with the body angle, the body sides fit snug to the neck, and the tenon holds every part tight, with no wiggle when it is seated. This takes time. A lot of time. And finesse. A lot of finesse. And experience. A lot of … WHOOPS! I purposefully left extra room in the neck blank in case I needed to start over again with the tenon. I did. Twice. That’s where experience shows, and why only the most senior craftsman deal with fitting the dovetail joints in the Martin factory. But, the third try seems to be the good one. I still have some final adjusting to do when the neck is carved and ready to be joined permanently, but for all intents and purposes, it works.   I guess I can begin fretting, now.

As I’ve stated, one of the goals for this uke build is to build on my skills and use hot hide glue. Well . . . I have sinned before you, my friends! Yes, I have strayed from my path, but for two very good reasons. The first transgression was using CA glue for the mother of pearl logo inlay. Its a non-structural part of the uke, CA is instant, it sticks to MOP better, and, well, its just the better choice.  (In the pic, its been rough sanded at the drum sander, and has some preliminary layout marks. All of that will be gone by the finish sanding.)

My second sin was in making up the neck blank, I used Titebond original wood glue, an aliphatic resin glue, a current standard in guitar making. Here, we decidedly DON’T want the glue joints to ever come apart, so reversibility is not needed, or wanted. Plus, with the large surface areas of the three laminations (mahogany/maple/mahogany), a longer open time is critical. One of the reasons I’m using a laminated neck in such a small instrument is the grain direction of the mahogany I had on hand. Ideally, you want perfectly quarter sawn stock to avoid any twisting of the neck down the road. But, with a laminated neck, you can use less than perfect stock, and have the two halves of mahogany work against each other, balancing things out. (The maple center strip just adds a decorative touch.) You can see the different grain lines in the end of the neck blank.

Next up, the dovetail neck joint, another new procedure for me (YIKES!)

The sides of the uke were bent on the hot pipe, and allowed to set in the mold. The bracing was cut, shaped, and glued to the top and back. Here’s where the speed of hot hide glue really shines; there’s no real need for clamping, just get the glue on the brace and the top, quickly position it, and press firmly for a minute or so (a little initial rubbing of the brace in position helps form a bond too.) Then, its good and stuck, and the bond will only grow stronger as it sets. And on to the next. Now, if I were dealing with full size guitar bracing, I may still want to clamp, but with small size of the use’s bracing, its easy to press on the entire length of the braces. The head and heel blocks were glued to the sides, and the kerfng was glued to the sides. After chiseling in pockets for the braces in the kerfing, it was now go time, time to glue the top and back to the sides.

So far, I had been using fairly high gram strength glue. (Hide glue comes in different “gram strengths,” thEve higher it is, the tackier and less open time there is, and the stronger it is supposed to be.) I had been using 251 gram strength, but for the larger glue surface of the back and sides, I mixed up a batch of 162 gram strength glue, to hopefully give me a precious extra minute of open time. As fast as I could, starting with the back, I spread the hot glue over all the kerfing, positioned the back, and pressed and clamped. It was ok, but I could still see a couple of areas that would need to be addressed. But, I had a plan. So, I repeated the same process with the top. Again, try as I might, I still had a couple of areas that didn’t get a good bond, whether from not enough glue, or not fast enough with the clamps. But here is where hot hide glue’s greatest liability is also its greatest asset. With modern glue, I would have to scrape all of the dried glue out of the joint, squeeze some more in, reclamp, and see how I did the next day. With HHG, I can just heat the affected area with an iron, work some more hot glue in, clamp, watching the joint close, and be done. The glue will stick to itself, and the heat and moisture of the new glue, will reactivate the old glue. Also, I don’t have to worry about being sloppy, hide glue doesn’t affect any finish, the way modern glue does.

So, with any remaining gaps closed, I can flush trim the top and bottom, leaving me with a closed box.

And, after routing the channels for the binding, its easy to see how well the reglueing went. No gap, even on the inner part of the joint.

Then, after bending the bloodwood bindings, and glueing them in, with purling on the top, the body was almost complete. Just a little scraping, planing (with the help of my favorite wee little ebony plane), and sanding to go.

And the body is done, waiting for a neck.

If you don’t succeed, stick, stick again. (As long as you’re using the magic glue!)

With the renewed wave of enthusiasm for ukuleles that has grown over the last few years, I decided on doing an uke build this summer, in Concert size (the second smallest.) Since its a small, relatively uncomplicated build, I also want to increase my skill set and explore building with the traditional luthier’s adhesive: hot hide glue. Aside from tradition (after all, that’s the only glue there was up to about a hundred years ago), HHG is preferred amongst many luthiers for it ease of disassembly for repairs (critical in violins), and its claimed superiority in transferring energy. It is supposed to cure more crystalline, with no creep, or movement.
HHG is sold dry, in a few different forms – granules, powder, button, etc. – which then has to be hydrated and cooked. So, following a standard recipe, I used a 1:1.9 ratio by weight of glue to water and let it absorb for an hour. Then, using a double boiler (well, a cheap pot on a cheap hotplate), I brought it up to its ideal temperature, between 140°-145°F. Anything much higher and the glue will begin to lose its strength. Anything cooler and it will start to set up too quickly.

According to recommendations, I kept it at temperature for a half hour, and then let it cool down before storing it in the fridge overnight. This is supposed to let everything meld completely.

The next day I got ready for my first HHG glue up: joining the top and back plates. When using HHG one of the things you have to be careful with is preparation. Joints must go together without gaps and without forcing, and clamping strategy has to be worked out ahead of time. Because it has such a short open time, compared with modern glues, there is no time to be fiddling with clamps after its been applied, you just have to put it on, clamp it up, and move on. This is good practice for any glue, so being forced to think through it with the HHG is going to reinforce good technique. So, after jointing the edges as well as I could, I prepared my clamps. Because of the diminutive size of the uke, I was able to use two parallel clamps.

I double checked that the thin plates wouldn’t buckle under firm clamping pressure, and that there were no gaps in the joint. Then, after bringing the glue back up to temperature, I brushed it on, clamped it quickly, and left it.

I unclamped after a couple of hours and, seeing that it looked good, left it to cure overnight. The next day, I sent it through the thickness sander to remove any squeeze out, and to get it to rough dimension. Everything was good, the glued up top and back had a nice clear ring when tapped, similar to before the glue up. With the form made, you can see the final appearance of the top.

So far, so good. Let’s hope I don’t find myself in any sticky situations as I proceed with my HHG experience!

This winter I tackled something a little different; off-topic, yet still on-topic. With all my other self made musical gear, I still needed somebody else’s amplifier to push it through (at least on the electric side.) So, with a very cold and snowy winter keeping me in the house, I tackled that final link in the chain: building a tube amplifier!

Now, I don’t pretend to know half of the electrical engineering knowledge it takes to design a guitar amplifier from scratch, so I decided to get my feet wet with one of the many amp build kits that are available. Typically, new builders start with a Fender Tweed Champ design from the ’50s, one of the simplest designs around (and yet still very useable. Its what Clapton recorded Layla with!) But, I already had that sound covered in my stable. So, I went looking for a kit that took after Marshall’s early 18w Plexi amps from the mid-60s, able to go from crystal cleans at low volumes to crunchy overdrive when pushed harder. There were a number of companies that had one, but I ended up going with a U.K. outfit (Ampmaker) for price (even with int’l. shipping and tariffs it was cheaper than most of the U.S. kits), quality of components (hey, when making a British amp, why not British parts!), and, most of all, one of the best instruction manuals I’d seen (critical for a total novice.)

I got my tools collected and got to work, learning to solder along the way. I won’t go into the tech details (this is a woodworking blog, after all!), but here are some shots of the process.

The various capacitors and resistors soldered onto the turret board.

Leads attached to the bottom of the turret board. (Definitely had to label these before I put the board in the chassis!)

The turret board installed in the chassis, and the first wires connected to the tube sockets.

All of the socket, switch, and input connections made.

Transformers wired in. The completed innards!

In the end, after doing some careful testing (both un-powered and powered), I ended up with an amp that sounds as good, if not better, than what you can buy in the stores. But, it needed a home. Bolted to a piece of plywood was not only inelegant, but potentially dangerous, with the high voltages transformers waiting to zap a careless hand.

So, I built a cabinet for it, using some curly cherry and birdseye maple I had. Green & Green inspired lightly protruding finger joints provide the structure, with a curly maple handle to provide portability. A good project to warm up my WW’ing chops, after the winter break.

Here’s a quick clip of what it sounds like.

(O, and Happy 100th post to me, btw!)

The Tinman’s Heart guitar is finished and delivered to a happy customer! It has it’s own page, of course, filled with details and pictures. And, like every major build, after it was finished, it had to have a photo shoot. In past years (thanks to teaching at a University as part of a Fine Arts school), I have had access to professional grade photo lights to take my pics. Sadly, they are temporarily out of commission, so I had to improvise. My first option was to use an inner office with copious fluorescent lights. Some of the final pics came from that set. But, depending on the angle of the camera and the lights on the guitar, some shots were downright ugly, with bizarre color in the image.

Here’s a shot of the front that wasn’t too bad:

And here’s the very next shot of the same from from a different angle that has gone horribly, horribly, awry:

After reviewing the shots from that first set, and finding not enough useable ones, I went searching for a new locale. Luckily, our Fine Arts building has a large glass enclosed atrium by the auditorium, and the rainstorm had finally stopped and was starting to clear. This gave me the ideal lighting environment: natural, but not direct, light.

Here’s the back of the headstock under fluorescents:

Here’s the same shot from almost the same angle, with natural light:

Big difference! The Osage orange actually looks orange rather than green (yech!), and the mahogany has that beautiful rich color that it is known for.

So, that is the first component to good pics, GET THE LIGHT RIGHT! But, that’s not the end of the story. Even with the right light, you still have to work out the best angle. Especially with reflective surfaces, you have to make sure that you aren’t getting light bouncing back, washing out whole sections of the piece. (This is particularly tricky with guitars since they have almost no flat surfaces; everything is curving every which way.)

Here’s a shot (in natural light) of one side of the guitar that is reflecting too much:

From the other side, the light is much kinder:

But, the most important factor in getting good shots is this: Take as many pics from as many angles in as many environments as you can! Pixels are cheap, use as many as you can. You can always delete the really awful ones if you’re running out of space in the camera. (A second card is also a good idea!) The more you have to choose from, the more likely that you’ll find just the right shot.

Nobody wants to end up with a Tinman that looks like he’s green to the gills!

OK, maybe not building an actual ship, but this entry is all about bridges and portholes.

I’ve been focussed on teaching and getting in some WWing and luthiery instead of posting blog entries, but as the guitar build nears its conclusion, I’d thought I’d catch up a little.

The body and neck are all completed, so before I can get it into the finishing room I need to make the bridge. We decided to go with cocobolo for the bridge, instead of ebony as we originally decided on, so that it would match the cocobolo bindings etc. I had a leftover blank from the Beast builds that was only partly cut out that would fit this size bridge easily. Before doing any shaping, while it is nice and flat and rectangular (-ish), I routed out the saddle slot and drilled the pin holes.

Then I could cut the shape to outline. I created a new design to compliment the jumbo body shape, echoing the round belly, while providing an upper shape that would achieve the most important function of the bridge: to tie into the X-braces for best transmission of the sound vibrations.

With the outline cut at the bandsaw and the saw marks smoothed, I could proceed with the shaping with rasp and file and sandpaper.I wanted a multilevel bridge, with the central belly being the highest part, then the much lower wings, but with a front ridge to provide strength and (again) maximum vibration transference.

Positioned on the body (with all the blue tape helping with position and layout marks):

After masking the bridge and fingerboard glue surfaces, and much finish sanding, it went into the finishing room for its first coats. Two coats of blonde shellac were followed by two coats of an oil/varnish, applied VERY thinly, and sanded to 600 grit between coats. I wanted to get things sealed and protected before the next step, which was to cut a sound port into the upper bout. This is a new innovation that the customer wanted that is to allow the player to hear the sound of the guitar better while playing. Not having done any before, I was concerned, especially with the osage orange, which has a tendency to want to splinter at cuts.

Sure enough, I had some trouble with the edges, so I decided to make a decorative porthole ring to go around the hole. Easy to say, tricky to do. It had to be thin enough to not be intrusive, but it also had to follow the curves of the upper bout. I used the same mallee burl that I used for the endgraft and heelblock. Using a combination of a circle cutter, band saw and drum sander, I was able to get my ring. Then I fired up the bending iron to carefully bend it to shape. After letting it dry in the form overnight, it was ready to glue into place.

Some homemade spool clamps proved to be the best method for glueing.

And, after some finish sanding and some shellac, voila!

Now, back to more finish coats, then final assembly and setup.