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33K views 28 replies 12 participants last post by  Thorbjorn88 
#1 ·
Introduction

Hello, Lumberjocks!

It's time to chronicle an actual project from me. I hope you enjoy the first of a series of blog posts about the construction of what I've always dreamed is the first of many acoustic guitars.

BACKGROUND

Long ago, perhaps 25 years ago in high school, my uncle, Roe, constructed a banjo and gifted it to my mother (yes, his sister). It was beautiful to me and though I never really learned to play it other than to strum open and barred chords, I greatly admired it. Being both a beginning guitarist and a very green woodworker at that time, it immediately let me know that constructing an actual musical instrument was highly possible, especially since Uncle Roe undoubtedly made that banjo with meager tools, at most. Still, life goes on, so I catalogued that into the back of my mind.

Once I married and moved into my current home, I started equipping my garage workshop, as I've detailed on my "workshop" page here at LJs. Being trapped into a home and kitchen remodel for three years now, I've plugged away…taking time in between to do various projects just to keep me from going insane, but unfortunately I haven't taken the time to talk about those projects. And truthfully, I still have a ton of cabinet work to finish and I have promised a new mission style reading table for my wife by Christmas.

THREE WEEKS AGO

So I'm browsing around on my iPad late at night while watching my DVR'ed Texas Rangers baseball game, as usual. I run across two inspirations. First, I decide to get an online subscription to Fine Woodworking magazine, and doing so allowed me to read the story about William "Grit" Laskin and his spectacular guitars. Honestly, I'd only very vaguely remembered who Laskin was. I knew he invented the "arm rest," which I'd previously seen first on one of Phillip Lang's (LJ's own) guitars. But while exploring more, I ran into YouTube videos with all the O' Brien videos and, specifically, the "Hand Tooled Guitars" guy. It was the latter which convinced me that building a guitar didn't seem as daunting of a task as I previously supposed. It made me think that because the construction of a guitar actually has a lot of down time and gaps inherent in the process that I could start one simultaneously with my other projects.

While I began my planning this guitar, trying to understand more about the materials, hardware, and tools for all the jigs that I would have to make, not just the guitar itself, I started to believe that I should just do everything with proper aplomb, that the jigs shouldn't be just temporary fixtures and the mold shouldn't be merely topped with 1/4" plywood. I shouldn't just make my side bender a torch-heated pipe, but rather a big stretchy thing-a-ma-jig complete with a heated blanket. After all this guitar deserves to be treated like a king.

TOOLING

I've long believed that you don't buy tools until you truly need them. So for this guitar, I knew that my Dremel tool would be insufficient for cutting rosette and binding/purfling channels and that my current selection of routers would be a bit too powerful…so, of course, I welcomed to the family a new DeWalt DW611 trim router, complete with plunge base. Of course, it just means that I have yet two more jigs to build, a circle cutting jig for the rosette and a right angle jig for the binding cuts. Even so, I've already made a locker name plaque for my son's first day of 6th grade with my new router, bearing guides, and Rockler letter templates!

However, it is the LACK of tooling that might pose problems. First, I've resisted getting a bandsaw for quite a while now. I've been holding out for that Laguna 14 SUV and I don't want to temporarily clog up my garage shop space with a typical 14" bandsaw, not to mention that I have yet to truly NEED one. For this guitar, I really don't need one…but as I'm thicknessing my lumber - everything will be from scratch - and as I'm rough cutting my guitar shapes with a Black and Decker jig saw I am quite certain that I'll be wishing for one. However, when I get to cutting the shape of the neck, I know I'll like have to head to my friend's shop to borrow his 14" Jet bandsaw.

But the real concern I have with my tooling deficiency is the lack of a way to thickness really thin, highly figured boards. I have started my milling (stay tuned to part 2) and I already see that my 14" DW 735 planer and hand planes aren't going to let me sneak up on the final thickness without tons of tear out. I've gotten one side of this guitar near its final thickness, but only wit careful use of my high dollar, fancy Black and Decker "Dragster" belt sander. In truth, it's not a bad little tool for the price, but it's a "drag" compared to what I REALLY need for this project…and I just might have a surprise for you in the next couple of posts! ;)

GUITAR DESIGN

I've been playing guitar since 1985. I have a Bachelor of Music degree. I personally own a Taylor 814ce acoustic and a 1979 Gibson Les Paul Standard. But I'm not a very good guitar player. I just never liked practicing much and a severe injury to my left wrist in 1998 really made playing guitar quite painful, even today. I'm proficient, but that's about it. But I love guitars and I'm certain that I would be inspired to play my own creation more often. I just have to stock up on painkillers.

Though I have played guitar now for most of my life, I have never really been a good student of it. I realized in my research that I have never really bothered to properly set up any of my guitars, nor have I really understood the differences in shapes, as standardized by Martin Guitars. I DID know the way different wood choices affect sound, however, so at least that's something! But for this guitar, I've been forced to do my due diligence. When I stumbled across the aforementioned "Hand Tooled Guitar" (HTG) guy, I really liked his design in the videos and I studied the difference in 12-fret and 14-fret (clear of the body) models. His design calls for a 12-fret, OM shape/sized guitar….which is similar to my current Taylor, only it is a 14-fret model so typical of MOST guitars built today. It appears that designers would rather give more fret access and sacrifice some sound response because of the natural location of the bridge in such designs, chiefly, nearer the guitar waist.

But for this guitar, and any 12-fret design, the bridge falls more in the guitar's lower bout, and most expert players prefer the sound this design yields. In addition, the original design as presented by HTG calls for a florentine cutaway and a severely bowled back shape. I love the florentine cutaway look and I knew that any fret access lost by the 12-fret design would be recovered by the cutaway. As for the bowled back, it's a bit too severe for my tastes, so I'll likely flatten it out a bit, much like my Taylor.

So, on these blog pages in the near future, expect a OM/000 sized, 12-fret designed acoustic guitar built from scratch!

NEXT UP: wood selection, initial milling, and tons of pictures!!!
 
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#3 ·
What an adventure. I've made several guitars but it was years ago. I went to the Maine school of Luthiery back in the day. I've noticed that in many of the books there are some elaborate jigs that are used to glue on tops and such. There are much more simpler and just as effective ways of doing that. In fact except for a few good deep clamps nothing special is really needed. For example. To glue a top or back on, place it on a board with L hooks surrounding the body of the guitar. use strips of bike inner tube or large elastics crisscrossed over the top to glue it. I've seen very elaborate flexible stick units that rise to the ceiling and other elaborate methods for doing the same thing.

You can take your top down to thickness with a large plane. The back the same way but planed across the grain if the wood is very hard.

Glueing the top and back matched pieces together: lay a strip of wax paper on the bench. Apply glue and lay wax paper and a strip of wood over that on the seam. lightly clamp the seam down. Tap three finish nails on each side then make six little wedges out of wood. Tap the wedges between the nails and wood and it's clamped.
It can be really simple but just as effective.
 
#4 ·
It's funny that you mentioned those simple methods, CotL. And that is why I thought I'd start on my guitar. Now, I like to build shop fixtures and jigs, so many of my initial plans in that regard will certainly grow into something more substantial…I know myself. But knowing that you can actually do all this without getting too fancy gives a little more comfort going into the process. And reading so much recently about construction techniques and options gives me confidence that whatever problems there are, I probably have more than one way of dealing with them.

But, yeah, in thinking about attaching the back and sides, I've seen inner tubes, surgical rubber, screw clamps, and any other of seemingly a thousand different ways to do it. However, I probably still build that "go-bar" deck with the flexible poles. But those aspects of the build can be figured out when I actually get there.

Thanks for the comments, guys.
 
#7 ·
Wood Selection and Milling

In this part of the construction blog of my OM-sized 12-fret acoustic, I'll give you some thoughts about wood selection and milling…

WOOD SELECTION

I mentioned in Blog post #1 that I wanted to construct this guitar from scratch. Not that I don't like the nice selection of exotic back and sides as seen on eBay, but I greatly enjoy the process of taking a tree (or large board) and seeing something built from it. Though Walnut isn't a traditional choice for guitars, it is a proper tonewood, and its use in a guitar not only provides beauty, but also a sound that many say combines qualities of rosewood and mahogany, which are perhaps the two most widely used wood types for acoustic guitar backs and sides. But because I have some really nice walnut boards on hand, I envision them spending the rest of their lives reincarnated as my first guitar.

For the soundboard, I did buy some various selections from eBay, mostly because it's difficult to find traditional soundboard woods purchased by board/foot in Texas. Cypress is about as close as it gets near here, and that's not quite a traditional choice.

It should be said that my current Taylor 814ce guitar incorporates Indian Rosewood, Sitka Spruce, and a Mahogany neck. I am familiar with the bright sound and separation of tones that this combination produces, but I've often thought the combination to be a little too treble-"y", almost harsh for my tastes. Therefore, I've long wanted to own a cedar topped (Western Red) guitar, which mellows out the tone a bit. However, it does get a little muddy when strumming hard.

But because of my choice of walnut for the back and sides, I felt that I should stick with spruce. One of the selections I acquired was billet of Sitka Spruce, which shows nice tight quartersawn grain. When planed to thickeness, it would likely grade to AAAA quality, near master grade, suffering only a small streak of pinkish color is an otherwise very light, uniform creamy white background. I wonder if a good A/B bleach treatment might help to balance out the pink (?) so I'll probably give that a try should I choose it for a future guitar.
However, for this guitar, I've chosen to go with a european Carpathian Spruce, which happens to have some nice "bearclaw" figure. The color is extremely light, very uniform, and I feel that it will look really good with the walnut. But more than that, I feel that by sticking with in spruce family with my soundboard that it will retain some brightness of sound when compared against the walnut, which I think might focus on more of the mid-tone frequencies than other choices. The grain isn't as tight with this european variety, even getting a little wider at the edges of bookmatched pair. But I believe it will produce a nice result and I expect the bearclaw to provide a nice little visual statement.

Pictured below is the Carpathian Spruce, the second image shows a bit of the "bearclaw" figure…
Brown Rectangle Wood Floor Flooring


Rectangle Wood Flooring Hardwood Composite material


For my choice of neck, I have decided to use some curly maple, laminated with some of the walnut. I think the neck will do a good job of tying together the darkish walnut back and sides with the very light spruce soundboard.

I have a plethora of woods for headstock, fretboard, bridge, rosette, and bindings, so I will be experimenting with some designs that might utilize something even as exotic looking as Black Palm. However, I want to be certain that the guitar doesn't get too "busy" with too many different types of wood competing with each other. It's tempting to just go with a simple Box Elder Burl that I have handy…complemented with some tasteful Abalone. But those finishing touches will certainly evolve with the construction of the guitar itself.

MILLING

The result of what you are about to see only drives home one important point: if you want to build a guitar from scratch, then a large band saw and a thinkness sander would be your best friends.

Since I have no true friends, I must resort to thicknessing my materials the old fashioned way…elbow grease.
Chair Wood Wood stain Gas Hardwood


Yep, kerf the sides with the table saw which serves as guides for the hand saw or reciprocating saw. And notice what you do when you still haven't built your dream workbench? Yep, sawhorse and parallel clamps do the job!

Eventually, you win…
Table Wood Rectangle Outdoor furniture Composite material


And with a few runs through the planer (going only to 1/4") you can see the potential…
Wood Purple Grass Asphalt Agriculture


There is a small knot that I will need to work around, and I'm not entirely sure yet if I want to use the small section of sapwood, but we'll cross that [guitar] bridge when we come to it.

As for the sides, here is the board I've chosen, and as you can see it has some tremendous curl passing through some pretty tight quartersawn grain…
Table Wood Flooring Floor Wood stain


The table saw is all I need for the resawing, and notice that if you leave a little ridge in the middle it makes resawing a much safer operation…
Wood Rectangle Wood stain Hardwood Plank


And here's the sides cut down a little bit…
Brown Wood Flooring Wood stain Floor


The above image shows one of the boards after being thicknessed down to around .15". Final thickness will be in the neighborhood of .08" to .09", though I have fears of being able to properly bend this wood due to it's substantial curl figure. Of course, without a thickness sander, achieving final thickness on wood like this is extremely difficult because of the tearout you get between the curl. The planer really tore out these boards going to 1/4", and my smoothing planes just aren't sufficient enough to keep from gouging out the wood in these areas. I did resaw these boards carefully down to around .18 on the table saw, which I do NOT wish to do very often. However, I used a hand-held belt sander, half-sheet sander and oscillating rotary sander to get that down to that .15" hard-earned thickness.

It was at that moment that I hatched a plan to BUILD a thickness (drum) sander, and I'm convinced I could have built a nice one…that is until this happened:

Performax 22/44

Despite the fact that the Austin is 200 miles away from my DFW address, it was a no-brainer for me…and I consider this a very fortunate deal. To add to my good fortune, my cousin lives in Austin and was kind enough to pick it up for me…and I hope to get down next weekend to pick it up. At that point, I'm hoping that it will make quick, neat work of all my guitar wood, no matter how thin it is!

After the sides, I moved on to the neck lamination, which includes two walnut slats sandwiches between three curly maple slats…
Table Wood Floor Flooring Wood stain


Wood Rectangle Wood stain Varnish Plank


Wood Table Tool Gas Hardwood


Which produces this result with a little clean-up…
Wood Lectern Flooring Floor Wood stain


The middle board was left a little shorter to receive a natural groove for the truss rod; however, I have decided to go with a different type of rod than my original plan so I will be shimming this slot. To get the head-angle of 15 degrees, I used the miter sled on the table saw (ignore the very dirty blade please)...
Wood Creative arts Naval architecture Automotive exterior Flooring


Clean the blade and I don't get these burns…
Wood Flooring Hardwood Rectangle Wood stain


And after a little clean-up with the block plane…
Wood Automotive exterior Gas Automotive lighting Bumper


...and the end is cut to 90 degrees…
Wood Hardwood Wood stain Gas Flooring


Finally, I can now layout the neck block, to prepare for further shaping. I will certainly make a trip to my friends house to borrow his bandsaw for these rough cuts…
Wood Table Output device Desk Wood stain


Incidently, the roughed in drawing on the neck stock "heel" shows more of a classical guitar type of construction. I will be changing this and going with a sliding dovetail for the neck-to-body attachment. The neck will lay flush with the top so that the fretboard may sit directly on the soundboard. Note that the 12-fret line will be directly at the edge of the guitar. Scale for the guitar will be 25.4 inches.

Stay tuned for PART 3 of the BLOG: Completing the guitar mold, the bending form, and the bending "machine"!!!
 

Attachments

#8 ·
Wood Selection and Milling

In this part of the construction blog of my OM-sized 12-fret acoustic, I'll give you some thoughts about wood selection and milling…

WOOD SELECTION

I mentioned in Blog post #1 that I wanted to construct this guitar from scratch. Not that I don't like the nice selection of exotic back and sides as seen on eBay, but I greatly enjoy the process of taking a tree (or large board) and seeing something built from it. Though Walnut isn't a traditional choice for guitars, it is a proper tonewood, and its use in a guitar not only provides beauty, but also a sound that many say combines qualities of rosewood and mahogany, which are perhaps the two most widely used wood types for acoustic guitar backs and sides. But because I have some really nice walnut boards on hand, I envision them spending the rest of their lives reincarnated as my first guitar.

For the soundboard, I did buy some various selections from eBay, mostly because it's difficult to find traditional soundboard woods purchased by board/foot in Texas. Cypress is about as close as it gets near here, and that's not quite a traditional choice.

It should be said that my current Taylor 814ce guitar incorporates Indian Rosewood, Sitka Spruce, and a Mahogany neck. I am familiar with the bright sound and separation of tones that this combination produces, but I've often thought the combination to be a little too treble-"y", almost harsh for my tastes. Therefore, I've long wanted to own a cedar topped (Western Red) guitar, which mellows out the tone a bit. However, it does get a little muddy when strumming hard.

But because of my choice of walnut for the back and sides, I felt that I should stick with spruce. One of the selections I acquired was billet of Sitka Spruce, which shows nice tight quartersawn grain. When planed to thickeness, it would likely grade to AAAA quality, near master grade, suffering only a small streak of pinkish color is an otherwise very light, uniform creamy white background. I wonder if a good A/B bleach treatment might help to balance out the pink (?) so I'll probably give that a try should I choose it for a future guitar.
However, for this guitar, I've chosen to go with a european Carpathian Spruce, which happens to have some nice "bearclaw" figure. The color is extremely light, very uniform, and I feel that it will look really good with the walnut. But more than that, I feel that by sticking with in spruce family with my soundboard that it will retain some brightness of sound when compared against the walnut, which I think might focus on more of the mid-tone frequencies than other choices. The grain isn't as tight with this european variety, even getting a little wider at the edges of bookmatched pair. But I believe it will produce a nice result and I expect the bearclaw to provide a nice little visual statement.

Pictured below is the Carpathian Spruce, the second image shows a bit of the "bearclaw" figure…
Brown Rectangle Wood Floor Flooring


Rectangle Wood Flooring Hardwood Composite material


For my choice of neck, I have decided to use some curly maple, laminated with some of the walnut. I think the neck will do a good job of tying together the darkish walnut back and sides with the very light spruce soundboard.

I have a plethora of woods for headstock, fretboard, bridge, rosette, and bindings, so I will be experimenting with some designs that might utilize something even as exotic looking as Black Palm. However, I want to be certain that the guitar doesn't get too "busy" with too many different types of wood competing with each other. It's tempting to just go with a simple Box Elder Burl that I have handy…complemented with some tasteful Abalone. But those finishing touches will certainly evolve with the construction of the guitar itself.

MILLING

The result of what you are about to see only drives home one important point: if you want to build a guitar from scratch, then a large band saw and a thinkness sander would be your best friends.

Since I have no true friends, I must resort to thicknessing my materials the old fashioned way…elbow grease.
Chair Wood Wood stain Gas Hardwood


Yep, kerf the sides with the table saw which serves as guides for the hand saw or reciprocating saw. And notice what you do when you still haven't built your dream workbench? Yep, sawhorse and parallel clamps do the job!

Eventually, you win…
Table Wood Rectangle Outdoor furniture Composite material


And with a few runs through the planer (going only to 1/4") you can see the potential…
Wood Purple Grass Asphalt Agriculture


There is a small knot that I will need to work around, and I'm not entirely sure yet if I want to use the small section of sapwood, but we'll cross that [guitar] bridge when we come to it.

As for the sides, here is the board I've chosen, and as you can see it has some tremendous curl passing through some pretty tight quartersawn grain…
Table Wood Flooring Floor Wood stain


The table saw is all I need for the resawing, and notice that if you leave a little ridge in the middle it makes resawing a much safer operation…
Wood Rectangle Wood stain Hardwood Plank


And here's the sides cut down a little bit…
Brown Wood Flooring Wood stain Floor


The above image shows one of the boards after being thicknessed down to around .15". Final thickness will be in the neighborhood of .08" to .09", though I have fears of being able to properly bend this wood due to it's substantial curl figure. Of course, without a thickness sander, achieving final thickness on wood like this is extremely difficult because of the tearout you get between the curl. The planer really tore out these boards going to 1/4", and my smoothing planes just aren't sufficient enough to keep from gouging out the wood in these areas. I did resaw these boards carefully down to around .18 on the table saw, which I do NOT wish to do very often. However, I used a hand-held belt sander, half-sheet sander and oscillating rotary sander to get that down to that .15" hard-earned thickness.

It was at that moment that I hatched a plan to BUILD a thickness (drum) sander, and I'm convinced I could have built a nice one…that is until this happened:

Performax 22/44

Despite the fact that the Austin is 200 miles away from my DFW address, it was a no-brainer for me…and I consider this a very fortunate deal. To add to my good fortune, my cousin lives in Austin and was kind enough to pick it up for me…and I hope to get down next weekend to pick it up. At that point, I'm hoping that it will make quick, neat work of all my guitar wood, no matter how thin it is!

After the sides, I moved on to the neck lamination, which includes two walnut slats sandwiches between three curly maple slats…
Table Wood Floor Flooring Wood stain


Wood Rectangle Wood stain Varnish Plank


Wood Table Tool Gas Hardwood


Which produces this result with a little clean-up…
Wood Lectern Flooring Floor Wood stain


The middle board was left a little shorter to receive a natural groove for the truss rod; however, I have decided to go with a different type of rod than my original plan so I will be shimming this slot. To get the head-angle of 15 degrees, I used the miter sled on the table saw (ignore the very dirty blade please)...
Wood Creative arts Naval architecture Automotive exterior Flooring


Clean the blade and I don't get these burns…
Wood Flooring Hardwood Rectangle Wood stain


And after a little clean-up with the block plane…
Wood Automotive exterior Gas Automotive lighting Bumper


...and the end is cut to 90 degrees…
Wood Hardwood Wood stain Gas Flooring


Finally, I can now layout the neck block, to prepare for further shaping. I will certainly make a trip to my friends house to borrow his bandsaw for these rough cuts…
Wood Table Output device Desk Wood stain


Incidently, the roughed in drawing on the neck stock "heel" shows more of a classical guitar type of construction. I will be changing this and going with a sliding dovetail for the neck-to-body attachment. The neck will lay flush with the top so that the fretboard may sit directly on the soundboard. Note that the 12-fret line will be directly at the edge of the guitar. Scale for the guitar will be 25.4 inches.

Stay tuned for PART 3 of the BLOG: Completing the guitar mold, the bending form, and the bending "machine"!!!
The wood is beautiful! The contrast is going to be perfect. And there's nothing prettier than a curly neck IMO. Great choice!

I think spruce is a safe bet for the top. There are lots of mixed reviews about walnut tone. Some say bright, some say dark, some say neither. Haha. My only experience with it was with an electric. That's a moot point here. The one thing everyone agrees on is it's beautiful and it's musical. Pretty much all you need.

You're giving me gas for a new acoustic. I may have to get out the roledex of excuses. "but honey I NEED one" doesn't work anymore. lol
 

Attachments

#12 ·
The Mold and the Bending Machine

When I last left you, we were right at the point of beginning construction on many of the jigs and forms that will make this endeavor much easier. Conveniently, the timing works very well since I'm still awaiting the opportunity to make it down to Austin to pick up that Performax 22/44 that I got off eBay (thanks to my cousin, Brady, for getting it for me). This, of course, will allow me to get all that beautiful wood down to thickness easily and more precisely.

In the meantime, this blog entry will detail some of the progress being made on the main mold, which will hold the sides during construction, and the side bending "machine." Yes, I decided to build something that would make this guitar, and future guitars, without all of the headaches traditionally involved with bending over a heated pipe. More on that later.

Dimension Changes

In Blog #1, I mentioned that part of my inspiration for building a guitar at this time came from seeing a You Tube series of video from the "Hand-tooled Guitars" guy. I gained the confidence required for tackling something I always thought would be one of the more ultimate expressions in woodworking. But, more than that, I really liked the design of the guitar, which he classified as an 12-fret OM thin body guitar. I'm not too interested in building a thin body design, yet, but I did like the basic shape, so I ordered an acrylic template sent my way for $12.

In viewing the template and comparing it with my "grand auditorium" (GA) style Taylor guitar, I realized that I wanted the lower bout to be a little wider. So, in tracing out the shape onto the sheets of high-grade plywood that I would be using, I used the template as a "french curve" to connect the markings of the new dimensions I would employ on this guitar. A typical GA guitar is similar to a Dreadnaught, being almost identical in its dimensions except for its width at the waist, where the GA curves are more reminiscent of Marilyn Monroe as opposed to Charlize Thearon. Therefore, this guitar body, and its mold, will have the following dimensions…

Body Height - 20.5"
Upper Bout Width - 11.75"
Waist Width - 9.875"
Lower Bout Width - 15.5"
Depth of Body - 4.75" (tapering to the neck)

Creating the Main Mold

After tracing the shape, a jigsaw is used to rough cut half of the guitar out of the plywood. The new Ridgid spindle sander is then used to sand to the line. Five more "halves" are roughed out with the jigsaw and a straight pattern bit is used on the router table to duplicate the clean lines of the first half, which is used as the pattern for the rest.

Wood Hardwood Flooring Gas Wood stain


The rough cut outs from the mold are placed stacked together as well to be used as a form for the bending machine. In the meantime, I clean these up simply with the spindle sander. It does not need to be perfect, since minor errors in the form will be averaged out a bit by bending through spring metal slats (more on that later).

Wood Gas Rectangle Automotive exterior Wood stain


Three halves are then stacked per side, showing the complete shape of the final mold…

Wood Automotive exterior Gas Composite material Naval architecture


And those are then clamped up and screwed together…

Blue Line Wood Gas Engineering


And finally, a board is screwed into the bottom to hold the halves together and a large clasp is employed at the top to keep the halves closed and registered with each other. The bottom board flexs to allow an opening at top top of perhaps a 1/2" or so, which is enough to allow the guitar sides to slide out.

Wood Wood stain Hardwood Varnish Plywood


That is put aside for a while and I begin work on the "machine."

Bending Machine Construction

Now the fun part…why do something minimal when you can have tons of fun building something really complicated?

I did my studying and I realized that the highest rate of success when it comes to bending guitar sides happens by bending entire sides (or ribs) over a large form, using uniform heating across the entire board. That leads luthiers (and pretenders like me) towards one of three different designs.

1.) An "unheated" machine where the board is boiled and simply pressed onto a form.
2.) A machine that uses powerful, dimmer-controlled light bulbs under a hollow form to provide heat (Fox Bender)
3.) A machine that uses a silicon rubber heating "blanket" and a temperature controller (or dimmer) to provide heat atop a solid form.

My machine of choice is #3. Why? Three reasons.

1.) I already had the solid form from having constructed the mold.
2.) The success rate for this machine is very high, being versatile and precise with its heating controls
3.) I wanted to fool around with a cool temperature controller. :)

To start, I build towers for the device from high grade 3/4" plywood. These towers would be slotted and would hold a shaped board that would be screwed down by some sort of screw/clamp/vise thingie. This board, shaped to match the curve of the guitar's waist, presses and secures the sides at that point. Truthfully, I had no idea what I would use for the vise "thingie" when I started this step…

Wood Luggage and bags Gas Backpack Bag


Slots for the towers are added via hand-held router, straight bit, and guides. A 3/4" plywood bottom is added.

Wood Hardwood Gas Flooring Automotive tire


The boards for the form are connected with lots of double stick carpet tape and a bottom board is screwed onto the bottom, which will serve as a guide to properly position the form into the machine. Boards are added to the front and back of the base to receive the form.

Shown is the curved press board that will be laminated to another sheet of ply. The board is shaped on the spindle sander. Did I say I love that machine?

Wood Wood stain Floor Flooring Plank


So, what to do for the vise-clamp-pressing-down thingie?

After work one day, I thought I'd get inspiration while walking around my local Harbor Freight store. I knew they wouldn't have large screws, but I thought about maybe getting one of their cheap bench vises and pilfering just the parts I needed. No, there's gotta be something else. Think!

Every design I had seen for this machine used a centrally-located screw, but in the back of my mind I was curious about what keeps the curve uniformly flat during the bending process when bottoming out the curved block? What's to keep this block totally square to the forms? Would it lift up at one side of the waist? Well, if I built it right, the answer is probably not, but I didn't want to take that chance if given another choice.

Then, walking down the aisle with the clamps, I saw a 12" wooden screw clamp for $10. Illuminated, I didn't even use a coupon on it. Yep, I paid full price at Harbor Freight.

I took my prized clamp home and I did this…

Idiophone Wood Rectangle Wood stain Font


After further trimming and rearranging of the barrel bolts and screws, I did this…

Wood Bumper Gas Automotive exterior Wood stain


The holes in the top of the curved block are recesses for the screws as they are loosened (lifted) away from the form. Because the screws are double-threaded, with left and right threaded halves, I knew that I'd have a total travel of TWICE the distance from the bottom of the holes to the barrel bolts in the blocks. And, yes, those blocks are re-purposed from the clamp. In total, it gives over 4" of travel. Plenty enough to slide in a straight side and slide out a freshly bent side (with its form).

And when fitted to the towers, you get this…



Of course, the screws would have to be cut, but that's a piece of cake.



The blocks are attached with pocket screws to the curved press. Here is the bender with the "waist vise" complete and in the down position…



With a nice fit at the waist! The only real complication is that by using this woodscrew and reversing one of the handles, tightening the clamps means that you can throw "lefty-loosy, righty-tighty" right out the window! But really, it's no big deal and it feels right when you do it. Plus, it assures that I get equal pressure across the waist.

Playing with Electronics

About the time I finished the machine's construction, the toys came. Namely, a 6" x 36" silicon rubber heating blanket ($88 from Omega.com), a "k" thermocouple ($9 on Amazon), and a 1/16 DIN PID temperature controller ($26 from Amazon).

I had my buddy, Ross, who is smarter than me, come over to assist with the fun. Once we realized that the controller is merely a relay and that both the controller AND the blanket need their own power sources, we got the thing correctly wired and working properly…



PID stands for Proportion/Integration/Differentiation, which uses calculus to control how the controller reacts when the temperature gets to its setup point. Though I'm a math teacher and teach calculus, I had no interest in delving into manually setting up the calculus, so we took it through its "auto-tune" setup. We had some issues at first. Compared to my Ideal voltmeter (with its temperature sensor), the thermocouple just didn't seem very responsive…taking a long time to register. At least, that is until I realized that my placement of the thermocouple at the heating element was leaving the tip of it exposed. Doh!

Once corrected, the PID controller just zoomed. Heat of the blanket began to match the voltmeter reading very closely and once it reached its set-points the PID auto-tuning really got locked in.

Lets play! I had a remnant of a thin walnut board that would be perfect for a test piece. So, I soaked it in my swimming pool for 10 minutes, put it underneath the blanket, and began putting pressure on the waist. Because the spring clamps aren't installed yet (spring loaded clamping cauls work the board ends down and hold it in place), we awkwardly held everything down with parallel clamps. It produced this…



Woot! Ross and I did a giggle dance. I felt like I was Tom Hanks on a tropical island having just started a fire! Too cool. I took it to school this week for "show and tell," whereas my high school kids were mildly amused.

PID Temperature Controller Enclosure

If you purchase a bending machine from LMII (Luthier's Merchantile), you pay over $500 for their setup. With it, you get a controller in an actual box.

So, I needed a box.

I have a couple of "boxes" around the shop that were experiments while learning the Incra TSLS system. One box, just the right size for this application, was 1/2" milled marblewood sides joined with corner post dovetails made of walnut. The box had some chip outs, but it was salvageable enough to sand it up a bit, fill some gaps, fashion a walnut lid, and cut out some holes for the controller face and the cables. This is the result…



And, still without the spring clamps for the ends, and a slight modification to the end pieces to raise it off the table a bit (more clearance for longer sides), here is a larger beauty shot…



Final Thoughts

It's a long build, but I think it will make bending my sides a breeze. The test piece I used was pretty much bent by the time the controller reached the set-point…and I only left it cooking for about 10 minutes afterwards, before I let it cool off just enough to pull it out of the machine. A little spring back, but not much considering that you would typically leave them in the form overnight (without heat). The test piece was a little thin on one end, but a little thick on the other, so it was a good test.

I will add the spring clamps later…unless I can device something a little more creative. I will also be receiving some spring steel slats from McMaster-Carr that are sized to match my heating blanket. The idea is to create a sandwich of the layers, whereas the steel uniformly distributes the heat, provides smoother action during the bend, protects the blanket from the clamps, and provides a great visual to any places where the board isn't properly against the form.

I'm excited to add this tool. Whereas you certainly do not need this to build a guitar, it will definitely encourage me to build MORE guitars. And it's given me thoughts to even other woodworking projects that might incorporate bent boards and laminations.

-----------------------

NEXT BLOG: Rosette design and Performax 22/44 thicknessing
 

Attachments

#13 ·
The Mold and the Bending Machine

When I last left you, we were right at the point of beginning construction on many of the jigs and forms that will make this endeavor much easier. Conveniently, the timing works very well since I'm still awaiting the opportunity to make it down to Austin to pick up that Performax 22/44 that I got off eBay (thanks to my cousin, Brady, for getting it for me). This, of course, will allow me to get all that beautiful wood down to thickness easily and more precisely.

In the meantime, this blog entry will detail some of the progress being made on the main mold, which will hold the sides during construction, and the side bending "machine." Yes, I decided to build something that would make this guitar, and future guitars, without all of the headaches traditionally involved with bending over a heated pipe. More on that later.

Dimension Changes

In Blog #1, I mentioned that part of my inspiration for building a guitar at this time came from seeing a You Tube series of video from the "Hand-tooled Guitars" guy. I gained the confidence required for tackling something I always thought would be one of the more ultimate expressions in woodworking. But, more than that, I really liked the design of the guitar, which he classified as an 12-fret OM thin body guitar. I'm not too interested in building a thin body design, yet, but I did like the basic shape, so I ordered an acrylic template sent my way for $12.

In viewing the template and comparing it with my "grand auditorium" (GA) style Taylor guitar, I realized that I wanted the lower bout to be a little wider. So, in tracing out the shape onto the sheets of high-grade plywood that I would be using, I used the template as a "french curve" to connect the markings of the new dimensions I would employ on this guitar. A typical GA guitar is similar to a Dreadnaught, being almost identical in its dimensions except for its width at the waist, where the GA curves are more reminiscent of Marilyn Monroe as opposed to Charlize Thearon. Therefore, this guitar body, and its mold, will have the following dimensions…

Body Height - 20.5"
Upper Bout Width - 11.75"
Waist Width - 9.875"
Lower Bout Width - 15.5"
Depth of Body - 4.75" (tapering to the neck)

Creating the Main Mold

After tracing the shape, a jigsaw is used to rough cut half of the guitar out of the plywood. The new Ridgid spindle sander is then used to sand to the line. Five more "halves" are roughed out with the jigsaw and a straight pattern bit is used on the router table to duplicate the clean lines of the first half, which is used as the pattern for the rest.

Wood Hardwood Flooring Gas Wood stain


The rough cut outs from the mold are placed stacked together as well to be used as a form for the bending machine. In the meantime, I clean these up simply with the spindle sander. It does not need to be perfect, since minor errors in the form will be averaged out a bit by bending through spring metal slats (more on that later).

Wood Gas Rectangle Automotive exterior Wood stain


Three halves are then stacked per side, showing the complete shape of the final mold…

Wood Automotive exterior Gas Composite material Naval architecture


And those are then clamped up and screwed together…

Blue Line Wood Gas Engineering


And finally, a board is screwed into the bottom to hold the halves together and a large clasp is employed at the top to keep the halves closed and registered with each other. The bottom board flexs to allow an opening at top top of perhaps a 1/2" or so, which is enough to allow the guitar sides to slide out.

Wood Wood stain Hardwood Varnish Plywood


That is put aside for a while and I begin work on the "machine."

Bending Machine Construction

Now the fun part…why do something minimal when you can have tons of fun building something really complicated?

I did my studying and I realized that the highest rate of success when it comes to bending guitar sides happens by bending entire sides (or ribs) over a large form, using uniform heating across the entire board. That leads luthiers (and pretenders like me) towards one of three different designs.

1.) An "unheated" machine where the board is boiled and simply pressed onto a form.
2.) A machine that uses powerful, dimmer-controlled light bulbs under a hollow form to provide heat (Fox Bender)
3.) A machine that uses a silicon rubber heating "blanket" and a temperature controller (or dimmer) to provide heat atop a solid form.

My machine of choice is #3. Why? Three reasons.

1.) I already had the solid form from having constructed the mold.
2.) The success rate for this machine is very high, being versatile and precise with its heating controls
3.) I wanted to fool around with a cool temperature controller. :)

To start, I build towers for the device from high grade 3/4" plywood. These towers would be slotted and would hold a shaped board that would be screwed down by some sort of screw/clamp/vise thingie. This board, shaped to match the curve of the guitar's waist, presses and secures the sides at that point. Truthfully, I had no idea what I would use for the vise "thingie" when I started this step…

Wood Luggage and bags Gas Backpack Bag


Slots for the towers are added via hand-held router, straight bit, and guides. A 3/4" plywood bottom is added.

Wood Hardwood Gas Flooring Automotive tire


The boards for the form are connected with lots of double stick carpet tape and a bottom board is screwed onto the bottom, which will serve as a guide to properly position the form into the machine. Boards are added to the front and back of the base to receive the form.

Shown is the curved press board that will be laminated to another sheet of ply. The board is shaped on the spindle sander. Did I say I love that machine?

Wood Wood stain Floor Flooring Plank


So, what to do for the vise-clamp-pressing-down thingie?

After work one day, I thought I'd get inspiration while walking around my local Harbor Freight store. I knew they wouldn't have large screws, but I thought about maybe getting one of their cheap bench vises and pilfering just the parts I needed. No, there's gotta be something else. Think!

Every design I had seen for this machine used a centrally-located screw, but in the back of my mind I was curious about what keeps the curve uniformly flat during the bending process when bottoming out the curved block? What's to keep this block totally square to the forms? Would it lift up at one side of the waist? Well, if I built it right, the answer is probably not, but I didn't want to take that chance if given another choice.

Then, walking down the aisle with the clamps, I saw a 12" wooden screw clamp for $10. Illuminated, I didn't even use a coupon on it. Yep, I paid full price at Harbor Freight.

I took my prized clamp home and I did this…

Idiophone Wood Rectangle Wood stain Font


After further trimming and rearranging of the barrel bolts and screws, I did this…

Wood Bumper Gas Automotive exterior Wood stain


The holes in the top of the curved block are recesses for the screws as they are loosened (lifted) away from the form. Because the screws are double-threaded, with left and right threaded halves, I knew that I'd have a total travel of TWICE the distance from the bottom of the holes to the barrel bolts in the blocks. And, yes, those blocks are re-purposed from the clamp. In total, it gives over 4" of travel. Plenty enough to slide in a straight side and slide out a freshly bent side (with its form).

And when fitted to the towers, you get this…

Wood Gas Engineering Armrest Hardwood


Of course, the screws would have to be cut, but that's a piece of cake.

Wood Gas Automotive tire Hardwood Wood stain


The blocks are attached with pocket screws to the curved press. Here is the bender with the "waist vise" complete and in the down position…

Wood Wood stain Hardwood Flooring Automotive wheel system


With a nice fit at the waist! The only real complication is that by using this woodscrew and reversing one of the handles, tightening the clamps means that you can throw "lefty-loosy, righty-tighty" right out the window! But really, it's no big deal and it feels right when you do it. Plus, it assures that I get equal pressure across the waist.

Playing with Electronics

About the time I finished the machine's construction, the toys came. Namely, a 6" x 36" silicon rubber heating blanket ($88 from Omega.com), a "k" thermocouple ($9 on Amazon), and a 1/16 DIN PID temperature controller ($26 from Amazon).

I had my buddy, Ross, who is smarter than me, come over to assist with the fun. Once we realized that the controller is merely a relay and that both the controller AND the blanket need their own power sources, we got the thing correctly wired and working properly…

Wood Engineering Hardwood Machine Plywood


PID stands for Proportion/Integration/Differentiation, which uses calculus to control how the controller reacts when the temperature gets to its setup point. Though I'm a math teacher and teach calculus, I had no interest in delving into manually setting up the calculus, so we took it through its "auto-tune" setup. We had some issues at first. Compared to my Ideal voltmeter (with its temperature sensor), the thermocouple just didn't seem very responsive…taking a long time to register. At least, that is until I realized that my placement of the thermocouple at the heating element was leaving the tip of it exposed. Doh!

Once corrected, the PID controller just zoomed. Heat of the blanket began to match the voltmeter reading very closely and once it reached its set-points the PID auto-tuning really got locked in.

Lets play! I had a remnant of a thin walnut board that would be perfect for a test piece. So, I soaked it in my swimming pool for 10 minutes, put it underneath the blanket, and began putting pressure on the waist. Because the spring clamps aren't installed yet (spring loaded clamping cauls work the board ends down and hold it in place), we awkwardly held everything down with parallel clamps. It produced this…

Electrical wiring Wood Gas Electrical supply Wire


Woot! Ross and I did a giggle dance. I felt like I was Tom Hanks on a tropical island having just started a fire! Too cool. I took it to school this week for "show and tell," whereas my high school kids were mildly amused.

PID Temperature Controller Enclosure

If you purchase a bending machine from LMII (Luthier's Merchantile), you pay over $500 for their setup. With it, you get a controller in an actual box.

So, I needed a box.

I have a couple of "boxes" around the shop that were experiments while learning the Incra TSLS system. One box, just the right size for this application, was 1/2" milled marblewood sides joined with corner post dovetails made of walnut. The box had some chip outs, but it was salvageable enough to sand it up a bit, fill some gaps, fashion a walnut lid, and cut out some holes for the controller face and the cables. This is the result…

Wood Sky Flooring Gas Tints and shades


And, still without the spring clamps for the ends, and a slight modification to the end pieces to raise it off the table a bit (more clearance for longer sides), here is a larger beauty shot…

Wood Motor vehicle Automotive design Naval architecture Engineering


Final Thoughts

It's a long build, but I think it will make bending my sides a breeze. The test piece I used was pretty much bent by the time the controller reached the set-point…and I only left it cooking for about 10 minutes afterwards, before I let it cool off just enough to pull it out of the machine. A little spring back, but not much considering that you would typically leave them in the form overnight (without heat). The test piece was a little thin on one end, but a little thick on the other, so it was a good test.

I will add the spring clamps later…unless I can device something a little more creative. I will also be receiving some spring steel slats from McMaster-Carr that are sized to match my heating blanket. The idea is to create a sandwich of the layers, whereas the steel uniformly distributes the heat, provides smoother action during the bend, protects the blanket from the clamps, and provides a great visual to any places where the board isn't properly against the form.

I'm excited to add this tool. Whereas you certainly do not need this to build a guitar, it will definitely encourage me to build MORE guitars. And it's given me thoughts to even other woodworking projects that might incorporate bent boards and laminations.

-----------------------

NEXT BLOG: Rosette design and Performax 22/44 thicknessing
Wow! I will be watching this one. The gigs look great. I really like how you made the side bending gig. I did a guitar stand using bent wood lamination. In hine sight I thought I shouuld have steamed the smaller curve. I wonder how the heating device your'er using would work on a thicker lamination? Well done!
 

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#19 ·
Rosette Design, Joining the Soundboard, and Performax 22/44 Fun

I'm swamped with two other concurrent projects at the moment, but I have found time to contemplate a Design for the rosette, as well as play around a little with my new eBay bargain, the Performax 22/44 drum sander.

Rosette Theory

The idea of the rosette is derived less from artistic design opportunities, which it certainly is, but more by the structural need to reinforce the sound hole in such thin, soft woods like spruce, cedar, redwood, or whatever stock is normally chosen for the guitar top. Doing so can help prevent cracks from developing at the sound hole edge and continuing across the face of the soundboard. Although some guitars will have minimal rosette designs, many will still provide reinforcement on the back side of the soundboard, to add back some thickness.

That said, I like modern art and opportunities for non-traditional expression. And because I wanted my first guitar to be a skill-builder for me, I decided against purchasing a complete rosette online in favor of designing my own. I knew I wanted to use some fancy, exotic woods pieced together to form the rosette ring, but I also wanted to be a little more creative than just a circular, symmetric inlay. I also wanted to do something that does not confine the rosette only to the sound hole area, but rather to expand the design, perhaps, up the fingerboard a little bit.

So, what to do?

The Math Guy

I teach high school math. This year, I teach mostly Geometry. When I think of a circle, I think of radii and diameters and circumferences and area formulas. I also think of Pi, which is the irrational number that is the ratio of a circle's circumference to its diameter, which is 3.1415926538 and so on and so on. But can I make a rosette connection with Pi? Hmm.

Google search.

I came up with this…

Green Plant Grass Terrestrial plant Art


That's a crop circle, and on the surface it looks really cool, but its also a representation of Pi. I guess aliens love Pi because, you know, the universal language of math, and all that. Here it is a different way…

Colorfulness Slope Circle Font Recreation


So, I thought I could do something similar, only beginning around the edges of the sound hole rather than at a circle's center. After a couple of quick renderings, here is what I came up with…

Circle Auto part Font Drawing


For now, ignore the notes I've made about the shape of the soundhole and the concept of a soundhole "ledge," which might be the dumbest idea to ever come across luthiery. But note that the soundhole will be slightly less than 4" to begin with, which allows for more room for "Pi" while making sure the circle doesn't get too big. This smaller soundhole will certainly affect the guitar's "voicing," but I'll cross that bridge, no doubt recklessly, when I come to that part of the build.

The design divides the circle into ten 36 degree slices representing our number system from 0 to 9. The rings start out at the starting line (a black mark) and spirals around counterclockwise, much like the crop circle does. A new material accounts for each digit of Pi, or, in the case of the first digit (3), no material at all. An abalone dot will represent the decimal and some herringbone will even give a hint to the direction of rotation. Borders will be in thin maple dyed red and/or black (not sure yet). Regardless, it will match the guitar's standard purfling. You will notice as well that Pi is represented up to 3.1415926, whereas an ellipsis continues the sequence up the fingerboard and into theoretical infinity. Material choices are the aforementioned abalone and herringbone, with possibly some purpleheart, some red gum burl I have handy, walnut to tie in the back and sides, and some end grain black palm (wait until you get a load of that).

Materials might change as I do this, and I might create some negative spaces during the process because I want to avoid it being too busy, but I think you might expect the result to look something a Raymond Kraut design seen here…

Eye Gesture Wood Symbol Font


Of course, when I actually do this and I ruin four or five soundboards, I'll probably end up just buying a pre-made rosette on eBay. :)

But I have added a nice set of spiral down cut inlay bits from Stewart-McDonald to go with my new DeWalt DW611 and I've made a wooden prototype of a circle cutter jig that I'll probably convert to acrylic. So, I'm hoping that I can make the precise routs for my inlay pieces. More on that soon.

Joining the Soundboard

Remember that European spruce soundboard? Well, now it's time to get it properly jointed and joined together.

Here are a couple of soundboard halves resting on the shooting board, which I did together using my Woodriver #5. The light one is the spruce and the darker one is redwood (which I'll use on another guitar down the road).

Wood Rectangle Hardwood Flooring Tints and shades


For me, the shooting board and jack plane makes for quick work of the jointed edges. And it produces some cool curls to boot!

Food Ingredient Kettle corn Recipe Cuisine


You know you have a good joint by using the "light test." If you hold the halves up to bright light and you can still see the light through the seam, then you've got more shooting to do!

Automotive exterior Couch Vehicle door Wood Tints and shades


Using regular old Titebond 1, some sandwich boards, non-stick wax paper, thick rubberbands, and Dr. Pepper, you have a easy method of doing the glue-up…

Food Gas Wood Box Packaging and labeling


It doesn't take a lot of clamping pressure. Once dried, here's the soundboard ready for final thicknessing.

Hood Rectangle Wood Textile Purple


A couple of month ago, I dreaded the next step of trying to thickness the boards, particularly the figured walnut I will be using for the sides. But as you can now see, I've got a better method now…

Performax 22/44 Fun

I picked up that sander I won on eBay. It was good of my cousin, Brady, to pick it up for me down in Austin and I enjoyed spending a day with him making the exchange. Brady has the start of an awesome shop, with a hand-built workbench that I admire and some tooling for making some banjos and knifes…including forging the blades himself.

Although the sander is 15 years old or so, it's amazing how well it performs. As with many of our machines, there really isn't a whole lot that can go wrong. For $405, this was a Craigslist deal of gloat worthy proportions.

Table Gas Machine Wood Metal


The drum is a little off, however, shaving about 5 thou lower on the drum end, but I actually used that setting to push through my Euro Spruce soundboard. By running it through both ways, it actually makes the edges a little thinner than the center, which I've heard will help loosen the guitar up a little when new. For me, it will probably prove disastrous, but what the heck, right? Target thickness was around 100 thou inches, which might be a little thin. I'll address that when I brace the soundboard.

Here's a video of the machine running, working the soundboard down to size…



I'll definitely reset the drum when I do the back and sides and the materials for inlays, headstock veneers and binding/purflings; but its something that will be a quick fix and doesn't really add up unless sanding boards the entire width of the drum.

Closing Thoughts

Ambitious, huh? We'll see if I can pull off that rosette design and truly make it as elegant and intricate as I hope. I'll be taking my time with that and I'll certainly be practicing a lot. But that's kinda the point, right? I mean, I know I can build a guitar. I just don't know if I can build a really good one, so I want to get a good grasp on the methods and tools required to make that possible. The result should be a decent looking and sounding guitar, with enough of a satisfying and educational experience to make it possible to produce more (and better) guitars in the future.

NEXT BLOG: Inlaying the Rosette, part 1
 

Attachments

#20 ·
Rosette Design, Joining the Soundboard, and Performax 22/44 Fun

I'm swamped with two other concurrent projects at the moment, but I have found time to contemplate a Design for the rosette, as well as play around a little with my new eBay bargain, the Performax 22/44 drum sander.

Rosette Theory

The idea of the rosette is derived less from artistic design opportunities, which it certainly is, but more by the structural need to reinforce the sound hole in such thin, soft woods like spruce, cedar, redwood, or whatever stock is normally chosen for the guitar top. Doing so can help prevent cracks from developing at the sound hole edge and continuing across the face of the soundboard. Although some guitars will have minimal rosette designs, many will still provide reinforcement on the back side of the soundboard, to add back some thickness.

That said, I like modern art and opportunities for non-traditional expression. And because I wanted my first guitar to be a skill-builder for me, I decided against purchasing a complete rosette online in favor of designing my own. I knew I wanted to use some fancy, exotic woods pieced together to form the rosette ring, but I also wanted to be a little more creative than just a circular, symmetric inlay. I also wanted to do something that does not confine the rosette only to the sound hole area, but rather to expand the design, perhaps, up the fingerboard a little bit.

So, what to do?

The Math Guy

I teach high school math. This year, I teach mostly Geometry. When I think of a circle, I think of radii and diameters and circumferences and area formulas. I also think of Pi, which is the irrational number that is the ratio of a circle's circumference to its diameter, which is 3.1415926538 and so on and so on. But can I make a rosette connection with Pi? Hmm.

Google search.

I came up with this…

Green Plant Grass Terrestrial plant Art


That's a crop circle, and on the surface it looks really cool, but its also a representation of Pi. I guess aliens love Pi because, you know, the universal language of math, and all that. Here it is a different way…

Colorfulness Slope Circle Font Recreation


So, I thought I could do something similar, only beginning around the edges of the sound hole rather than at a circle's center. After a couple of quick renderings, here is what I came up with…

Circle Auto part Font Drawing


For now, ignore the notes I've made about the shape of the soundhole and the concept of a soundhole "ledge," which might be the dumbest idea to ever come across luthiery. But note that the soundhole will be slightly less than 4" to begin with, which allows for more room for "Pi" while making sure the circle doesn't get too big. This smaller soundhole will certainly affect the guitar's "voicing," but I'll cross that bridge, no doubt recklessly, when I come to that part of the build.

The design divides the circle into ten 36 degree slices representing our number system from 0 to 9. The rings start out at the starting line (a black mark) and spirals around counterclockwise, much like the crop circle does. A new material accounts for each digit of Pi, or, in the case of the first digit (3), no material at all. An abalone dot will represent the decimal and some herringbone will even give a hint to the direction of rotation. Borders will be in thin maple dyed red and/or black (not sure yet). Regardless, it will match the guitar's standard purfling. You will notice as well that Pi is represented up to 3.1415926, whereas an ellipsis continues the sequence up the fingerboard and into theoretical infinity. Material choices are the aforementioned abalone and herringbone, with possibly some purpleheart, some red gum burl I have handy, walnut to tie in the back and sides, and some end grain black palm (wait until you get a load of that).

Materials might change as I do this, and I might create some negative spaces during the process because I want to avoid it being too busy, but I think you might expect the result to look something a Raymond Kraut design seen here…

Eye Gesture Wood Symbol Font


Of course, when I actually do this and I ruin four or five soundboards, I'll probably end up just buying a pre-made rosette on eBay. :)

But I have added a nice set of spiral down cut inlay bits from Stewart-McDonald to go with my new DeWalt DW611 and I've made a wooden prototype of a circle cutter jig that I'll probably convert to acrylic. So, I'm hoping that I can make the precise routs for my inlay pieces. More on that soon.

Joining the Soundboard

Remember that European spruce soundboard? Well, now it's time to get it properly jointed and joined together.

Here are a couple of soundboard halves resting on the shooting board, which I did together using my Woodriver #5. The light one is the spruce and the darker one is redwood (which I'll use on another guitar down the road).

Wood Rectangle Hardwood Flooring Tints and shades


For me, the shooting board and jack plane makes for quick work of the jointed edges. And it produces some cool curls to boot!

Food Ingredient Kettle corn Recipe Cuisine


You know you have a good joint by using the "light test." If you hold the halves up to bright light and you can still see the light through the seam, then you've got more shooting to do!

Automotive exterior Couch Vehicle door Wood Tints and shades


Using regular old Titebond 1, some sandwich boards, non-stick wax paper, thick rubberbands, and Dr. Pepper, you have a easy method of doing the glue-up…

Food Gas Wood Box Packaging and labeling


It doesn't take a lot of clamping pressure. Once dried, here's the soundboard ready for final thicknessing.

Hood Rectangle Wood Textile Purple


A couple of month ago, I dreaded the next step of trying to thickness the boards, particularly the figured walnut I will be using for the sides. But as you can now see, I've got a better method now…

Performax 22/44 Fun

I picked up that sander I won on eBay. It was good of my cousin, Brady, to pick it up for me down in Austin and I enjoyed spending a day with him making the exchange. Brady has the start of an awesome shop, with a hand-built workbench that I admire and some tooling for making some banjos and knifes…including forging the blades himself.

Although the sander is 15 years old or so, it's amazing how well it performs. As with many of our machines, there really isn't a whole lot that can go wrong. For $405, this was a Craigslist deal of gloat worthy proportions.

Table Gas Machine Wood Metal


The drum is a little off, however, shaving about 5 thou lower on the drum end, but I actually used that setting to push through my Euro Spruce soundboard. By running it through both ways, it actually makes the edges a little thinner than the center, which I've heard will help loosen the guitar up a little when new. For me, it will probably prove disastrous, but what the heck, right? Target thickness was around 100 thou inches, which might be a little thin. I'll address that when I brace the soundboard.

Here's a video of the machine running, working the soundboard down to size…



I'll definitely reset the drum when I do the back and sides and the materials for inlays, headstock veneers and binding/purflings; but its something that will be a quick fix and doesn't really add up unless sanding boards the entire width of the drum.

Closing Thoughts

Ambitious, huh? We'll see if I can pull off that rosette design and truly make it as elegant and intricate as I hope. I'll be taking my time with that and I'll certainly be practicing a lot. But that's kinda the point, right? I mean, I know I can build a guitar. I just don't know if I can build a really good one, so I want to get a good grasp on the methods and tools required to make that possible. The result should be a decent looking and sounding guitar, with enough of a satisfying and educational experience to make it possible to produce more (and better) guitars in the future.

NEXT BLOG: Inlaying the Rosette, part 1
Sorry about the pictures. I did this entry with the iPad and it looks like landscape mode wins out. I can fix that later on the PC.
 

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