Mopus chapter 8: The End is Near! (Part 3)

Whew, writing this update makes it seem like I’ve been working 24-7 on this guitar. Not exactly – it’s been almost exclusively weekends, and even then just during the day. It also may sound like I know what I’m doing, which is not exactly accurate. I’m just persistent in the face of failures. I confess to doing a lot of research, I tend to want to know every way to do something before I pick the way I’m going to do it. And I have to give huge credit to the over 50 hours of online courses I took from Robbie O’Brian. Those courses were worth every penny many times over. There is absolutely no way I could do this if that material was not available.

And now for he thrilling conclusion of the penultimate chapter of The Great Mopus Caper…

Before moving on to the frets, I first buttoned up a few loose ends, including permanently installing the carbon fiber rods with epoxy. I also worked on the truss rod and made adjustments to the neck to body joint. Eventually I ran out of pre-fretting things to do.

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Now for the frets. Fret wire comes in one continuous length which will be cut as needed to fit the fret slots. In this case I using gold EVO wire, which is made from a copper alloy rather than the usual nickel. It’s more durable, but I really chose it because it looks cool.

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One complication here is that I bound the fretboard with maple, which means that the slot doesn’t go all the way from edge to edge, it stops at the binding. So the fret tangs need to be removed short of the edge of the fretboard. I used a tool called a “fret nipper” to do this.

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I used a cut off section of my 16″ radius sanding block as a caul to protect the frets when hammering them in. It’s that block of wood with the 16 on it. Last time I just banged the frets in, causing dents in the wire which needed to be leveled out. Using the radius block caul worked much better.

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Once all the frets were in, I did an initial filing of the fret ends and then glued the fretboard to the neck. I used a 2×4 to apply slight upward pressure on the heel of the neck while the glue dried, this is to counteract the tenancy of the neck to bow slightly from the fret wire tension.

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Once the glue was set, I attached the neck temporarily so I could take a critical look at where Mopus was at.  I can almost visualize playing it now.

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Even though it looked good and all, a few measurements showed that there was still a way to go. The neck was much too thick, the heel block and headstock were not completed, and worst of all the neck angle was not quite right. But there is no doubt that this project has now shifted from basic construction to one of mostly finishing up. Almost every task from here on out is a final step.

The neck needed a lot of work. It turned out that I had to remove quite a bit of wood, much more than I originally thought. This took me days of futzing, as the neck is kinda important. And although you have to remove a lot of wood, it turns out you can’t put it back if you remove too much.  There is a very artistic and almost zen like feel to carving a neck, I suppose it similar to sculpting. You squint as you work, trying to visualize the curves you’re carving. You also have to be keenly aware of symmetry.

Here’s the neck close to it’s final shape:

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In the above picture you can see one detail I didn’t mention before. The back of the headstock has a walnut burl veneer. I actually researched veneers quite a bit, found a supplier that sent me an awesome and kinda large sheet of walnut burl. It first needed to be flattened with a special softener and weights.  I really like this material and will definitely use it again.

Now for the bridge. With the final words of Led Zeppelin’s “The Crunge” stuck in my head, I got to work.

…..Where is that confounded bridge?….

I started with a block of ebony…

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…and played with some ideas on paper.

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After changing my mind 2 or 3 hundred times, I cut out my final design on the bandsaw, and then roughed in the basic shape.

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Now comes the hard part, cutting the groove for the saddle bone. This is another area where a well thought out jig is essential. But to be honest, I’m starting to get a bit impatient, so I skimped a bit here and made a makeshift contraption, which was a borderline disaster. The key word here is borderline, and in the end I was able to get a usable groove cut. But just barely. I will definitely be over thinking this operation next time!

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Now for the peg holes. Pretty standard stuff here, they just have to be in the right place.

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After a bunch more shaping with frequent weighing to ensure the bridge had the right amount of mass, I finally found my confounded bridge.

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It’s the look I was going for, no hard edges, and sort of organic. Definitely doesn’t look factory made.

Before attaching the bridge to the body, it was time to address any remaining neck alignment problems and triple check everything. I made an alignment tool out of acrylic to help me visualize things. After more effort than I care to admit, I believe everything is aligned and positioned properly.

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And now for that terrifying moment when you just take a drill to the top of your guitar. I did this once before, but it still doesn’t feel right somehow.

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The holes allow me to use a special clamp for gluing on the bridge. After applying the glue and screwing down the clamp, I’ve reached the point of no return. Everything better be in the right place now!

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And that, my friends, brings us to the end of this Mopus update, which required a trilogy to tell.  The remaining tasks are to make a nut and saddle, install the tuners, do the fretwork, and string it up. That all by itself is maybe a day of work, so in theory I could play Mopus tomorrow. But what’s missing from that utopian thought is the finish. I am going to use the French polish technique on Mopus, and although I have some experience with it, I’m going to try to bump the technique up a notch this time. So this will take a little while, and I will have to try to be patient, which is extremely important for this type of finish. Wish me luck. I hope to be playing Mopus for the next update!

Mopus chapter 7: The End is Near! (Part 2)

Now on to making the fretboard.  What I was really after was not just a way to make this fretboard, but future ones as well.  Here’s Mopus’ future ebony fretboard being trued up:

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The biggest challenge in making a fretboard is to cut very precisely located slots for the frets to be installed into – the positions which are determined by the overall scale length. The slots have to be very clean, cut to a constant depth, and the width must be precise. There are various expensive ways to tool up for this operation – either by using a fancy miter box, or by using a table saw outfitted with a special (and therefor pricey) blade, but I wanted to come up with my own solution.

Besides cost, there was another reason I wanted to go my own way – I’m already planning the next guitar, which will have fan frets. A fan fret guitar (also called a multi-scale guitar), has frets which are not parallel, but spread out like a fan. The reason for this is to allow the bass strings to be longer than the treble strings. Google “fan fret guitar” if you’re curious about what I’m talking about. The problem with all the fret slotting solutions I mentioned above is that they assume all the frets are parallel.

So once again, I’m investing a lot of time and thought towards creating a tool just so I can make something else. Here’s what I came up with:

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There is a long fence that the fretboard seats against to keep it perfectly straight, and two lever clamps to lock it down. The saw is held in perfect horizontal alignment by use of 3 very high powered magnets embedded into a cross fence made of maple. This fence can swivel to cut any angle, and is locked down by a bolt. The saw has a blade whose kerf is exactly the width of the desired slot. The surface that the blade is stuck to is highly polished, so that the saw glides very easily, yet is held against the side with over 70 pounds of force due to the magnets. The depth of the slot is controlled by the height of the cross fence, the top will hit the ridge at the top of the saw blade when the depth is reached.  Got all that?  No? Well, the important thing is that it seems to work very well…

But now getting back to this guitar, all I need are standard parallel frets, so all that mumbo jumbo about fan frets is for sometime in the future. In this case all I had to do was lock the cross fence down at 90 degrees and begin sawing. Here’s the slotting jig in action:

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I did use a template and an indexing pin so that I didn’t have to think too much about exactly were the frets needed to be. For each cut you just index to the next position in the template and go.

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After tapering the fretboard sides on the bandsaw, I worked on the fretboard radius. This is a curve on the top of the fretboard to make it easier on the musician’s fingers. I chose a 16 inch radius, mainly because I already had sanding blocks for this.  I used makeshift fences to keep the radius even down the length of the fretboard. The fretboard is held in place with double sticky tape.

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Much elbow grease and some sweat and swear words later, I had my fretboard. Now for some fret markers.

I tried out a few fret marker ideas, and settled on a “random angle” design made from gold mother of pearl.  I just wanted something different, but not that hard to pull off.

I pulled out my nifty shell cutting jig (with the all important vacuum attachment) from 3 years ago, and cut some shell blanks:

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To inlay the shell, I first scored the outline, then filled it with chalk so I could see it. I used a Dremel with a special base and inlay bit to cut inside the lines.

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And I was able to get a pretty good fit. It doesn’t hurt that I’ve done this sort of thing a few times now.

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I used black CA glue to install the markers. It seems to blend pretty good with the ebony, and it’s certainly easier than the epoxy / sawdust method I had used before.  After some sanding and filing, here’s what my fretboard looked like at the time.

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That’s curly maple on either side of the fretboard, which I then glued on to dress things up a bit more. I also decided to put a curve at the very bottom of the fretboard (the part that will touch the sound hole).

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Since I was already cutting shell, I figured I should make the headstock logo at the same time. I originally thought I’d use blue abalone for this, looking cool and all, but after comparing against gold MOP, I went with the latter. It just stands out more IMO.

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After doing the headstock inlay, and a bunch of sanding and cleaning, I was anxious to see what Mopus would look like one day. Laying all the pieces together, Mopus is starting to resemble an actual guitar!

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The next steps are to install the frets and make a bridge. Those things are already done, but I think that’s enough info for today. Stay tuned for the super exciting part three of this update, coming to a theater near you! OK, maybe not a theater.

Mopus chapter 6: The End is Near! (Part 1)

My last Mopus update was way back in November, and so much has happened since that it almost seems like last year. Wait…

Mopus is getting close to being done. By “close” I probably still mean 3 or more weeks, but it’s clearly almost a thing at this point.  Here’s a story of how a couple pieces of nondescript wood became a guitar neck.

I started innocently enough with a nice but boring bit of mahogany.

The neck blank I’m using is not thick enough to carve out a headstock and a heel, so the idea is to build up those areas by cutting off pieces and gluing them back where needed. To begin with, to make the headstock I made an angled cut to glue back as a “scarf joint”.

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Here you can see how this already suggests a guitar headstock.

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Sure I could glue this up right now, but on this project I’m not really ever looking for the easy way out. So to make a more interesting neck, I sliced the board right down the center and laminated in three wood strips (maple flanked by purple heart) to create a center stripe.

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After gluing on the bit I previously cut off, and spending some quality time with some planes and other tools, I wound up with with this, which I think already looks pretty cool:

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But the headstock is way too thick for actual guitar tuners, so that part had to get a lot thinner:

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At this point I decided to take a detour and take care of something that has been bothering me for a while – the workbench I’d been using was small and wobbly. So, I made myself a heavy, sturdy and much larger workbench. Now we’re talking!

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I also made myself a router table at the same time, which I would need to finish the neck.  Yep, still another side project. In my guitar making experience so far, these kind of side trips seem to be the norm.  It’s a pretty true statement that guitar making (and likely wood working in general) is mostly about making things which enable you to make things.

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Armed with the router table, I could now cut channels in the neck for the truss rod. While I was at it, I also routed out channels for two carbon fiber rods which should make for a pretty stable neck. It was a bit of a mini project finding a source for carbon fiber!

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Next up was to glue the heel block on, and while I was at it, I figured I’d also glue on the headplate at the same time. Previously I had found and prepared some bookmatched striped Macassar ebony into a headplate, which I had all ready to go for this moment.

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And after a little cutting, trimming, rasping, and filing, this is what the neck looked like:

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Now to address attaching the neck to the body. This is not the easiest thing to do. I decided to use a mortise and tenon design with bolts (as opposed to the traditional dovetail joint).  These days, this is considered a better design, because it is much easier to adjust the neck angle should it become necessary.  The challenge is to cut a precise mortise in the guitar body (without destroying it), and to cut a precise tenon in the guitar neck. The angle between the neck and body is also tricky, as for various reasons the neck has to be at a calculated angle of about 1.5 degrees. Even a tenth of a degree makes a huge difference in playability, so this is not something one does freehand. A custom made jig is really a must, so I spent weeks designing and building such a jig.

I came up with a design that would work for both the mortise and tenon, using templates made from acrylic.  I had all sorts of problems and false starts making this jig, but in the end I was ready to do the cuts. Here I’m ready to cut the mortise into the guitar.

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And this is what the body mortise looks like.  Maybe you can appreciate how terrifying this cut could be. Not a lot of margin for error here.

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And here’s the tenon freshly cut into the neck heel:

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The holes in the heel are for barrel bolts which I’ll eventually use to screw the neck on.  Finding a source for these was a project into itself!

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This takes us to the middle of February.  At this point Mopus has a rough neck, a pretty complete body, and a way to connect one to the other.  That’s really great and all (and believe me I was thrilled), but there’s still a lot left to do and tell.  Mopus still needs a fretboard, some frets, and oh yeah, a bridge before we’re even in the ballpark. As I write this, all those things are now done! Stay tuned for part two!

 

Mopus chapter 5: Quite the Body of Work

It certainly has been awhile since I posted a Mopus update. I had it in my head to wait until I was “done” with Mopus’ body – figuring it was “just” another chapter in the story much like the back or the sides. But that was way back in July, and I was imagining something like 4-6 weeks tops for me to get the body done. Well, it’s taken me a good bit more than that, and it was way more involved than I was thinking. Also, I do have a day job and all.  I had quite the adventure, one fraught with false starts, lengthy side excursions, little disasters, frustration, and even some spilled blood. Here is my tail.

Joining the Top

Way back in July, i.e. “in olden days”, this part of the adventure started by thicknessing and joining a book-matched set of sitka spruce plates. Just like the back, the top has to be perfectly joined. I made a “shooting board” to help with this, allowing me to use some large jointing planes and also some sandpaper glued to a marble strip to make a good joint.

This part took quite a bit of work, but I barely remember it now. After I got the joint perfect, I used the same jig as I used for the back to glue it up.

Now that I had the material for the top, it should be a simple matter to make it into one, right?

The Rosette Extravaganza

The next step was to install the rosette (the decorative ring around the sound hole). I had a standard rosette ready to go for this, but that would be way to easy. Much better to make my own from scratch, I figured. And so began an adventure that lasted for months. I looked at all sorts of rosette designs, and finally decided maybe I’d try something made from interesting looking wood, arranged radially. I hunted down a selection of various kinds of wood to try out, and decided I really liked the look of spalted maple.  Spalted wood has dark bands caused by a fungus. In other words, it’s rotten wood. It’s not very structurally sound, but it sure looks pretty.

My design involved piecing together segments arranged in a ring so that the dark bands radiated outwards. I made a simple cardboard template to find interesting places to cut the wood.

I’m going to spare you the long version of the tale of what happened next, because trust me, it’s long. The short version is that I tried many ways of forming a nice ring out of these pieces. I made all sorts of molds out of plastic and wood and tried too many things to even remember them all. At one point I actually had a full rosette. I was so proud of myself – took all sorts of photos – I imagined it installed in the guitar top in short order. Then I went to thin it down to the necessary thickness, and it fell to pieces. I tried to repair it several different ways, and had to accept that I had to start over. This whole thing happened AGAIN – I managed to finish a second full rosette – with all new wood – but the glue stuck to the mold, and it broke trying to remove it. During all this, I even cut myself several times with an Exacto knife, mostly as a result of being frustrated and impatient, and I still have a small scar to remind me not to do that again. Once again, back to the drawing board, but this time armed with some experience.  I made a different mold, designed to release the rosette when done. And I also used purfling strips between the segments to make stronger joints.

I actually like the look of using the purfling between the segments better than the original. So, lets just pretend I intended to do it this way all along.

The process of routing out the top for the rosette and cutting the sound hole went so smoothly, I don’t even have anything interesting to say about it. I soon had the rosette mounted in the top. The whole rosette thing took so long I almost forgot what I had to do next. Anyway, this is what it looked like at the time – I’m pretty pleased with it!

After all that, the rest should be pretty easy, right?

The Soundboard Bracing

I was finally on to the bracing. What I had to work with is a few hunks of sitka spruce which I cut into strips and gradually formed into braces.  Even though there were a bunch of fun steps here – spanning multiple weekends – the whole thing actually went down pretty smoothly. Here’s a picture of using the go-bar deck to glue in the finger braces.

I spent quality time “voicing” the top – i.e. making it sound like a drum when you hold and tap it a certain way. This process is called making the top “responsive”. Lots of experience is required to know what a “responsive” top should sound like at this point. Only after you play the guitar do you know if you got it right or not. I did the best I could, but I do sense the top is stiffer and not as responsive as my first guitar, which if true will mean the next time I’ll know better. Anyway we shall see what it sounds like when I’m done.

It is tradition to sign the soundboard – so I put my John Hancock on the thing.  Here it is ready to be mounted on the body.

At this point I figured I was almost done. I just have to glue the top to the back, and I can move on to the neck, right?

Closing the Box

Before I glued the top to the body, there was one little detail to finish up on the inside – a label. I figured if I was going to spend a whole year making a guitar named Mopus, it at least needed a custom label. So I spent some time designing a label just for this guitar. It almost looks official!

Now for fitting the top to the body – chiseling notches where the braces stick through the sides. I’ve done this several times by now, so it doesn’t seem like a big deal to me anymore. After fussing with the fit for awhile, I glued the top using the go-bar deck with the top facing down on the radius dish.

And now Mopus had a body! Well, sort of… but surely we’re almost done with this, right?

The Binding Machine

All I need to do now is put some nice binding around the edges. I did this before, with plastic bindings, and although it scared the hell out of me at the time, I got it done. So I’ll just do the same thing again and move on. Well, not so fast. First I resurrected the binding jig I made for the first guitar – back when I was just a baby luthier.

It’s supposed to hold the router perfectly in alignment with the sides of the guitar, so that I can cut nice even channels for the binding strips. What I quickly found out, after several test runs, is that putting in wooden (in this case curly maple) binding is MUCH more complicated that the plastic bindings I used the first time. There is no margin for error now, and believe me, the first time there was plenty of error. So before I could put in the bindings I had to make a real “binding machine”, a jig to help make accurate binding channels. Yes, I could buy one, but they are silly expensive for a tool you use for maybe 10 minutes on each guitar. So I put the guitar building on hold, and embarked on a side project to make my own binding machine.

What you need is a way of holding the guitar in such a way that the guitar edge is level all the way around. This is challenging, because both the top and bottom are curved. A common and simple solution is to make a cradle with adjustable posts to support the guitar, so that’s what I did. So far so good.

The more difficult challenge is to make something to hold the router that only moves vertically.  That way, the router bit and the resulting binding channels are always parallel to the guitar sides. After looking a many possible designs, I went for a relatively simple approach of using ball bearing drawer slides to make a sort of vertical drawer with a shelf for the router to sit on.

Also, the router has to ride along just the very edge of the guitar, otherwise the depth of the cut will be uneven due to the curvature of the top and bottom. So I made a “doughnut” ring out of maple.  I cut it to a rough circle and glued a dowel into the center.

The dowel is so that I could chuck it into a hand drill and form the doughnut by spinning it against a belt sander. And that worked great. It did take some trial and error – in fact I had to make a second one. I did the final shaping with it chucked into the drill press, using fine sandpaper to get it smooth. I want it to smoothly glide on the edge of the guitar, so it has to have almost no friction. With some work and polishing it looked pretty good! OK, I suppose looks are besides the point, but still…

I also rigged up a counterweight to make the platform with router attached raise and lower easily with just one finger. There’s a pulley mounted at the top, and and a cable connects the platform up to and around the pulley to a small sack filled with heavy items in the back. I just played with what I put in the sack until it felt balanced.

After some shellac and some fine tuning, I have a binding machine! With the exception of the drawer slides and the pulley, I already had all the parts for this laying around, in the end saving hundreds of dollars. And now I have it, so I can use it for other guitars in the future.

At long last, I was now ready to cut the binding channels and get the body done. Surely this part will be easy, right?

The Binding Channels

After spending all that time designing a building a binding machine, the actual use was a bit anti-climatic. In reality it took maybe 20 minutes to actually cut the binding channels, and most of that was setting up the depth of the router on scrap wood. I had done many tests before starting so that there would be no surprises, and thankfully there were none.

And now for the simple matter of installing the binding. Or not.

Bending the Binding

With the plastic binding you see on nearly every guitar, you just push the binding into shape as you glue. No wonder it’s so commonly used. But silly me, I wanted to use curly maple. The cool shiny ripples in curly maple are caused by end grain, which in English translates into “very easy to break”. I had 6 pieces of binding ready and I only needed 4, so I had room for error, or so I thought.

With wood binding you have to first bend it into shape. I began by hand bending the sides using the bending iron, and I thought the first one came out pretty well, so I was feeling confident. The next one snapped in two almost immediately. And so did the one after that.  I went veeerrry slowly after that, and with much stress got 4 bindings bent. I even went the extra step of clamping them into the inside of the guitar form, wetting them and then heating them further with a heat gun and letting them sit overnight to make a snug fit. I was feeling really good. Will I ever learn?

After I removed them from the form, I realized to my horror that they were badly scorched / burnt in several places from the heating iron. For a time I thought I could sand out the burn marks, but no. I had no choice but to get more binding material and go to plan B, whatever that was.

While waiting for the replacement bindings to arrive, I figured maybe plan B would be to steam the bindings. So I built a steam box from a PVC pipe. I figured I could use the coffee machine milk frothing trick I did when I did the neck reset on the first guitar. I knew I saved that setup for a reason.

Well it looked cool anyways. After steaming the bindings, I found they were even more brittle than before! Apparently this is a well known annoyance about using curly maple, known by everyone but me. So it’s on to plan C.

The next idea was to press the bindings into shape with a form, a heat gun, and some clamps. The idea was to wrap the bindings in aluminum foil with a touch of moisture, and have a form rimmed with aluminum tape that I could heat more evenly versus using a bending iron. So I made a form to do this, which I wound up having to modify at least three times.

Although it eventually worked, a successful technique was not something I arrived at quickly. In fact, I’m humbled to say that I broke at least 10 additional binding strips before I had a set of 4 that I could use. Clearly, the next time I do this, I’m going for plan D, which is to use heating blankets and a bending machine (which I will also use to bend the sides) – just like the big boys do. That’s something I can obsess about in the future, but for now I’m really on to the final stretch for Mopus’ body.

Installing the Binding

Gluing in the binding also presents challenges, but now I was back to something I sort of did once before (although with plastic last time). But I already had the experience of using tape to hold the binding in place, and then using a really really long rubber band to hog tie the guitar and apply good even clamping pressure all the way around. I can be a little stressful, because you’re fighting the clock as the glue sets, so I put on some Chopin to calm me down, and went to work.

The End (of this chapter)

And so,  after many adventures over hill and dale, after frustration and injury, after fighting off orcs, trolls, and a balrog, and with absolutely no help at all from from wizards or eagles, I have a body for Mopus. Now I’m on to making the neck. I’m sure that will be easy, right?

Mopus chapter 4: How Mopus Got Her Back

Mopus got her back!

Dealing with the back was quite a bit more challenging than the last time I did this. After all, the kit I had built came with the back already the correct thickness, joined into one piece, and even cut to the right shape. All I really had to do was glue on the pre-made braces. This time, all I had to work with was two book-matched pieces of rosewood about twice as thick as I needed, and some mahogany to make braces from.

The first challenge was to get the wood down to the right thickness. I used my vintage Safe-T-Planer (bought on eBay a couple of years ago) to get close, and then applied a lot of elbow grease, scrapers, and an random orbit sander to bring it home. I have dreams of one day owning a thickness sander. Wonderful glorious dreams. Like I used to have about band saws. But I digress.

Then came the fun part of making a perfect glue joint to join the two pieces. OK, maybe not so fun. The challenge is that it really has to be perfect. The litmus test is to hold the two pieces up together to a strong light, and make sure no light can be seen through the joint. This is not that easy, and it took me a while to get it right. I used a “shooting board”, and some of my larger vintage planes (nicely sharpened of course), to get close and then a piece of marble with fine sandpaper to get closer. It really took quite a while before I was happy.

And just to make things as complicated as possible, I decided to add a maple accent strip down the center, which makes the glue up a bit more challenging. I wound up making a sort of improvised jig to do the glue up, using standard ceder shims as wedges to apply even side pressure. I used plastic packing tape to make glue-proof surfaces, and I held down everything with heavy objects (which explains the planes and marble in the following picture). This all worked very well, and I can’t really see the point of buying a special “plate joining jig”. So I don’t need to dream about those any more.

The back came out pretty nice, I really like the center strip, and the joint seems quite strong. But I still had to apply quite a bit more elbow grease, scrapers, sanders, etc, to get the whole thing to a nice uniform thickness. Not terribly fun. Did I mention I sometimes dream of thickness sanders?

I then simply went to my trusty awesome band saw and cut the back to the approximate final size. I also added a reinforcement strip down the inside center of the back, and to clamp it,  I used the go-bar deck I made back in guitar #1 days.

Then came the brace project. I cut some brace blanks out of a piece of mahogany, and then used my 15′ radius dish to get the correct radius on the bottom edges.

To mount the braces, I had to cut notches in the reinforcement strip and then glue them in place using the go-bar deck. Which gave me the the opportunity to re-discover the design flaw of using driveway markers as the bars. They are just to thick at 5/16″. You put one in, and 3 pop out. Sometimes you put one in and all of them pop out. When you’re doing a critical glue up, and only have a few minutes to work with, this just sucks. And that’s sugar coating it. So that will be THE VERY LAST #@%#  TIME I use those bars. I immediately went to eBay and found someone selling inexpensive 3/16″ fiberglass rods, bought 25 of them, and I’m never looking back.

Once that was over, I spent some quality time with chisels and planes to shape the braces. The process involves holding the back up to your ear while tapping at certain points to make the back “musical”.  Really knowing what you’re listening for takes lots of experience, so I did the best I could, all things considered.

Then there was the tricky part of fitting the back to the sides.  You have to cut notches for the braces to fit through, and it has to pretty much be perfect. This part I had done before, so I kind of actually knew what I was doing.  Within no time I had a nice fit on the back.

Armed with my new improved go-bars, it was pretty easy to glue up and clamp the back. Last time around I used dozens of spool clamps, and it was an memorable and anxious ordeal. But this time, it was almost too easy. Having the right tool for the job is a thing of beauty. Bam!, back glued.

And that children is the story of how Mopus got her back! She’s a very happy Mopus, and is now looking forward to getting a top. But that’s a story for another day. Good night and sleep well!

 

Mopus Chapter 3 – The rim’s the thing

After a bit of an adventure, the rim of the Mopus guitar is done. I made some missteps, some which I’ll mention and some that I won’t. One thing I find very rewarding about guitar building is that it seems like every mistake is an opportunity to get creative, and so far that’s been true of every guitar I’ve built. Mopus, being built completely from scratch, provides me far more opportunities to mess up get creative.

To make a rim from the sides, the first step was to cut blocks of mahogany to serve as heel and end blocks. When I built the Stew-Mac guitar kit, these came already made, but this time all I have is hunks of wood. Luckily, I now have a band saw, so making these blocks is a no brainer.

I decided to use white glue for the blocks, I was planning to use hot hide glue for everything, but I kinda chickened out here.  The main reason was that I somehow managed to cut the sides a little short, and I needed extra gluing time to make sure the rim hugged the mold. The sides therefore do not meet each other, but that’s not a problem because later on you wind up covering these areas anyway.  From here on out it’s hide glue….. I think.

I then got to try out my new radius dishes for the first time. The guitar back and front are not flat, they instead have a gentle radius. A radius dish is a sanding surface which conforms to the desired radius and using one ensures that everything will fit together nicely. Last time around, I made a “sanding stick” to do this, but this time I invested in some dishes from Canadian Luthier’s Supply . Here I’m putting a radius on the back of the rim:

Then I installed the kerfing. This is the slotted wood strips that line the rim and provide the gluing surface for the front and back. Just to make things extra complicated, I used mahogany “reverse kerfing” which is very fragile and requires pre-bending. And to really kick it up a notch, I used hide glue for the first time. Before I was done, I had several moments of panic, I even made the crazy mistake of bending the kerfing upside down and applying glue before realizing my mistake. I was all set to punt and order new kerfing, when Lucas said – “hey I thought the whole point of hide glue is that it’s reversible”. Truth. So armed with a heat gun and tiny scrapers, I removed the glue from each kerf until it looked like new. I managed to do that without breaking it, which is a miracle. Then I bent it the correct way, reapplied the glue, and continued with my life like nothing ever happened.

Next project was to cut strips of leftover rosewood to act as side braces. Not much to tell here, but i did get to build some clamp mouse traps. I keep re-discovering that you simply can’t have too many clamps. It’s just not possible.

Then I made an end graft for the butt end of the guitar. Since I made a mistake and cut the sides short, it’s only appropriate that I over-compensate by making a nice end graft. I used a bit of curly maple and some perfling, and made it a bit wider than usual, to cover my blunder:

To finish off the rim, I made a sound port. You don’t find sound ports on production guitars, but are common on high quality hand made instruments. They vent the sound so that the player can hear better, and actually improve the overall sound of the guitar. Since this is Mopus, named after a kitten, I decided to go with a paw print. To prevent cracking the sides, I first made a few thin strips of veneer on the bandsaw, one in maple and one in rosewood. I pre-bent them slightly to prevent cracking:

To make a clamping caul, I used Friendly Plastic – which becomes pliable when heated and then rigid when cooled.

Clamping the veneers in place:

After a couple of attempts, I settled on the graphic and position and glued on a template:

To cut the soundport, I used a Dremel and a cutting bit:

After some clean up with various files:

And now the rim is officially done!  

I might as well confess one other blunder innovative feature of Mopus. When clamping the guitar I discovered that the rim is thinner on one side than the other, by nearly 1/2″ in the lower bout. For the life of me I can’t figure out how this happened, I cut both sides together, and there really is no obvious way I could have done this. It’s much too late to do anything about it, so from now on I’m sticking with the story that this is an intentional feature. The idea is that when held in a playing position, the guitar will sit on your body more comfortably, since it’s thinner on the upper side. Yeah, now that I think about it, I definitely meant to do that.

Now… on to the back.

Mopus chapter 2: The Sides get Seriously Bent

A banner day in guitar building land! I got the sides bent, and although it wasn’t exactly smooth sailing, in the end it did work out. This was big for me, I’ve been wondering about how this would work out for quite a while. In fact, I did quite a lot of planning over several months, originally I was going to build a side bender which used silicone heating blankets, a temperature controler, and custom forms. I can’t even count how many times I almost ordered the parts, and it’s still likely I’ll get around to completing the thought one of these days. But what I did instead was buy a heating iron and bend the sides freehand. The main advantage in doing it this way is that I can bend any shape without making a special bending form each time. The down side is that quite a bit of practice is needed to master the technique.  In this case it’s trial by fire since rosewood is not cheap, and I’ve only got one set of sides. This way of bending is the old school approach and many many guitar sides have been bent using a hot pipe heated with fire or propane. There are commercially available electric bending irons available, but I was put off because most of them have cheap construction and are known to burn out easily. And they aren’t cheap. I ultimately wound up getting a custom iron made by Caramillo in the UK. The guy who made it teaches at the Newark School of Violin Making at Lincoln College and was a fun guy to deal with. The iron is made from solid milled aluminum and has two heating elements and a thermostat. 

 

But of course, before I get on with the bending, there’s always one last thing to do. I first needed to finish the mold, adding a bottom hinge, a latch, and 4 spreaders. That all was pretty easy, and I finished all that in no time. Here it is, finally ready for action:

 
Now on the bending. It took a while for the iron to heat up to close to 400 degrees, and as I never did this before it took me a good long time to get even the slightest bend. For a while I didn’t even think this was going to work out. But eventually, I got the idea, and managed to bend one side and then the other. It’s not perfect, but considering how many times I’ve done this, it actually came out pretty well.  

 

  

And voila, the sides are bent and chilling out in the mold! Next stop, making the rim. Since this is a rare weekend where I really have no other obligations, I might actually get that done!