tirapop

Not my style of guitar... but, compared to other pointy guitars, it has too many concave edges. The pointy guitar style suggests violence and aggression with visual references to edged weapons: broadaxes, scimitars, cutlasses. You need to connect concave edges with convex edges (with a nasty point). Check out the fantasy knives of Gil Hibbens for inspiration.

I think "You're So Vain" was written about Mick Jagger, whom Simon had briefly dated.

Google decoupage.

Maybe stick in a piezo and have it be your amplified acoustic?

Rich, Thanks for going through the trouble and doing these tests. I hadn't ever given any thought to the tuning and bending effects of string break angles and extra-scale string length until you did the tests and produced data. It's been interesting trying to think these things through. Let me go one record as being FOR thinking and FOR trying stuff. It all works hand in hand. Theory is usually informed by experience and observation. I wouldn't want to try to develop every theory from first principles. A lot of engineering is based on simplification and approximation. A lot of reality happens just outside of that. Much of engineering is based on empirical data and finding mathematical analogies that match the test data. You can predict results without really understanding the mechanism of how something works. Percentagewise, there aren't that many closed form solutions. Experimentation, without critical thinking, is too scattershot. Without some insight into what's driving your results, you'd blindly try things that wouldn't actually add anything to your knowledge. Your success would rely too much on luck.

Rich, I've got old and cheap stringed instruments with high friction (some friction?) nuts. Friction at the nut can cause higher string tension on the tuner side of the nut. When I tune up, I have to do things like pull the strings away from the fretboard or press down on the strings between the tuner and nut, to overcome friction to equalize tension. If I don't, after a couple minutes of playing, the string go sharp as I put enough load and vibration on the strings for them to overcome friction and equalize (or maybe only reduce the difference in) string tension. Not having had roller or Graphtech nuts is what made me think that friction is what is coming into play with your string break angle experiments. The only other thing that comes to mind, as a possibility, is if the string is getting "plastically deformed": the string is getting a kink where it goes over the nut/saddle. If the string gets permanently bent, it adds some resistance as you try to drag it over the nut/saddle. You have to unbend the bent part of the string. The amount of string movement is small, so, I don't think that's likely. You can experiment with the friction hypothesis using higher and lower friction nuts. It would also help to keep the break angle at the saddle constant and change only the break angle at the nut, to reduce the number of variables that effect the result. It would be nice to know what the string tension was on either side of the nut. Some bicycle wheel builders use spoke tension gauges. It use two fixed posts. It's designed so that the moving post (between the two fixed) exerts a standard force on the spoke. The dial gauge on the moving post shows how much deflection there is under that standard load. Builders use the gauge to keep spoke tensions uniform. The gauges are kind of spendy. Maybe you can improvise something. You could test the bent string hypothesis by changing the radius the string break angle is applied over. If the tuner side of the nut has no radius, string tension is more likely to form a kink in the string. If there's a large radius, there isn't enough bending load to kink the string. Comparing a kinked and unkinked string with the same break angle and same length should settle that question.

Erik, Don't sweat it. When the numbers all add up, it's hard to believe they're wrong... even if there's a mistaken assumption in there. You get extra points for entertaining dissent, keeping an open mind, and humility.

Hey Rich, cool experimental setup you have going. So, at one end you have a roller bridge and the other end there's a zero fret? When I was talking about string length and compliance, I should have said that I wasn't considering friction. That extra length of string past the nut and saddle only has an effect if there isn't so much friction that you effectively have a locked nut and saddles. When you increase the break angle, there's a larger component of load on the string pressing down on the nut/zero-fret/saddle. Friction force is proportional to this "normal" (perpendicular) force. The roller bridge should be less affected by friction, but, it still is. Friction is more a factor on the zero fret. If you had a roller bridge and roller nut, that used yet to be invented micro frictionless bearings, I would expect that break angle wouldn't have any affect on how far you had to deflect the string to raise the pitch a whole step. Break angle would still have an effect on how rattle-y the strings are when you're strumming. The normal force keeps the strings in their grooves. Mick, This is why intonation is adjustable. The correct intonation is going to be a function of scale length, string gage (maybe even brand), action height, string length north of the nut/zero-fret, friction at the nut/zero-fret, and head angle. In the old days, people just accepted imperfection... 3 barrel saddles on Teles, a straight (but slanted) bridge on Gibsons. If you want your intonation on your homemade wraparound bridge to be perfect, you should probably build your neck, mockup your body, buy an intonator from Stewmac, and determine the actual "correct" intonation. With all the variables in your body and bridge build, it probably won't be perfect when you put it all together, but, close enough.

Erik, I'm going to have to play my engineer card... for the past 20 years, I've been an aerospace structural analyst. This shows how all the trig works for the nut/saddle force to bisect the string force vectors. I apologize for the small size. I don't have an image hosting account. You'll probably have to print it out to read it. As I said, you're missing the horizontal load component at the nut. It isn't just vertical. You can demonstrate this to yourself with some dental floss and a beer coaster (as I just did). Tip the coaster on end, on your table, then use the floss to balance it. Coaster is vertical and floss is horizontal. Give the floss some break angle on one side of the coaster. You can keep the coaster vertical so long as you don't apply tension on the floss that exceeds the friction capability between the floss and the coaster. If you put any tension above that insignicant amount, the coaster collapses. Why does it collapse? The horizontal load component exerted by the floss as it breaks over the coaster. If you look at archtop guitars with floating (unglued) bridges you'll see that the break angles on either side of the bridge are nearly symmetric. The wide base of the bridge makes it less tippy than the coaster and allows some tolerance. It's helpful to imagine pulleys as others have suggested. Again, try to apply your method to a 90° string break angle. What answer do you get for string tension? In the solution I gave, where the string tension is equal on both sides of the nut/saddle, for a 90° string break angle, the nut/saddle reaction bisects it at 45°. The nut applies a horizontal reaction equal to the string tension and a vertical load equal to the string tension. It all balances. I haven't been following the string bending compliance part of the discussion, so I don't know what's being argued. Remember the string is acting like a spring. It follows Hooke's Law: F = kX. "F" is force, "X" is the amount it's stretched, and "k" is the spring rate. "k" is a function of the total length of the string, from the tuner to the ball end (locking nuts and bridge doodads notwithstanding). I think k = AE/L; "A" cross sectional area, "E" is elastic modulus, and "L" is length. For a given scale, tuned to a given pitch, a longer string will take less force to move a set distance. Compared to a shorter string, the same amount of displacement requires a smaller percentage of stretch for the total length of string. The longer string will also have to be displaced a greater distance to reach the same pitch as a shorter string.

Erik, In the absence of friction, the string tension is the same on both sides of the saddle is the same. I think the part you're missing is that the force between the string and the nut/saddle (NP in your diagram) isn't perpendicular to the nut-to-saddle string force (ST in your diagram). The force on the nut/saddle bisects the angle formed by the strings as it goes over the nut/saddle. If there's a break angle of the string over the nut/saddle, the string is trying to pull the nut toward the saddle. The nut/saddle reacts this with a load component opposite to the direction ST. Think about how your method would handle a 90° break angle.

I don't think so. Look at the front. It's got the same corner radius as the back. Look how thick the sheet metal is and then how much thicker the radius is. I understand your idea of using the weld bead to provide the material for the radiused corner. But, because the radius is so big, you'd have to put the weld bead on the inside of the joint. You can do that on one side of the guitar (top or back), but, not both. Welding the top/back to the sides and then grinding and shaping the joint is pretty labor intensive. Thermal distortion makes it harder to keep flat bits flat and to keep seams from gapping. It's doable, but, I don't think Trussart could afford to make them that way.

There was a thread where people showed pics of their houses. When Drak says "castle", it isn't much of an exageration. He can afford the wood he feeds to the WOD.

I like your pickguard, Algee. Prevail's pickguard is nice, but, it's too Danelectro for a Tele.

How much metalworking experience do you have? If you had a lot of experience, you wouldn't need to ask. If you didn't, then you probably don't have the skills/tools to do it. From the pictures, it looks like he uses stamped pieces of sheet metal, front and back, welded together along the side. A press and stamping dies are way out of the budget for a hobbyist. It's really hard to reproduce this by hand. Look at the back. The back is a sheet of metal that has to be bent along the perimeter of the guitar, with that constant corner radius. Imagine if you took a sheet of paper, held it over the back of a guitar and tried to fold the edges over. On inside curves, like the cutaway or the waist, the paper would tear. On outside curves, the paper would wrinkle, folding over the edge. Very skilled metalworkers can bend sheet metal around those corners without tearing or wrinkling it. They call it stretching and shrinking. When they shrink metal, they actually make the sheet metal thicker. They bend little wrinkles and gently flatten them out, while maintaining the overall shape. It's very painstaking work. You can only bend metal so much before it work hardens and gets too brittle to bend. Then it has to be annealed with a torch. When all that's done, you still have to weld the halves together, without it warping, and leave a nice weld bead that you can grind flat. There are easier ways to make a metal guitar body. Specimen makes aluminum guitars, including a Strat, that are screwed together. In the crudest, easiest method you could cut out sheets in the shape of the top and back of the guitar and bend a piece of sheet metal to form the sides of the guitar. The top/back could be attached to the sides with little bent sheet metal clips, pop-riveted to both parts. This would be kind of flimsy. A more ambitious plan would be to form a flange on those bent sides. Since the top and back would cover the flange, you could cut slots in the flange to take up the stretch or shrinkage a continous flange would have to accommodate. At worst, it would look like papercraft, with curved sides looking like a series of flat facets. At best, it could look as good as that Specimen guitar. Another alternative is to separate the flange from the sides. Make a continuous frame to rivet the sides and top/back to. It would be easier to form the flange than on the top or sides. You could do it with one of these.

Given the way the bridge straddles the cones and where the strings sit on the bridge, I think there's a bias in how the cones share bass and treble. More of the bass strings' energy is going to be driven into the pair of cones on the bass side and more of the treble strings' energy is going to go into the single cone on the treble side. I've got to believe that's what they were thinking when they came up with that arrangement. All the cones are the same size, so, they probably haven't been optimized as "woofers" and "tweeters".

Separate soundboxes? Made me think of tricone resonators. For FEA, at work, we use mainly NASTRAN and ELFINI. Some folks use ABACUS for non-linear composite analysis and analysis packages inside CATIA V5 CAD system. I'm used to doing static analysis. I have no experience with dynamic analysis and how to use FEA to design guitar tops. Most of the dynamic analysis of guitars I've seen has been modal analysis: free vibration with mode shapes and frequencies. I don't know how you use that information. Modal analysis is akin to tapping on an unstrung guitar. Putting on strings and then plucking them is something different. Just the string tension deflects the top, putting you into non-linear FEA. Superimposing a vibration on top of that pushes you near the limits of FEA and possibly into structural simulation software. That's completely off my map. I'd be interested to know this sort of thing is done. Quiz your mates from school about how they approached it.

Myka's and some build specs.

FEA would turn into a huge project all in itself. Typically you'd be doing this in conjunction with a lot of experimental testing. You'd need to come up moduli for wood/honeycomb sandwich panels (not in a book and anisotropic), damping coefficients, and work out end fixities/flexibilities. You could spend lots of time feeding the machine and trying to get it to match your test results, so that you could trust it.

"Tone" is wonderfully ill defined. When a lot of people go on and on about tone, rightly or wrongly, they're talking about sustain. Maybe this is because guitar with less sustain, the desireable elements of their tone decay more quickly. Anyway, sustain is all about energy transfer from the strings to the body... the slower the transfer, the more sustain. Greater mass and greater stiffness reduce string energy transfer. Less internal dampening also improves sustain. That all happens between the tuners and the bridge. For bolt-on necks, tight fitting neck pockets are desirable because they're stiffer. The compression load of the string on the neck bears directly from the neck to the body, instead of being cantilevered through narrow more flexible bolts. Neck through guitars are supposed to be superior because there's continuous wood from tuners to bridge. The rap against the bathtub route, with a trem, is that between the bathtub and the spring cavity, is a thin wafer of wood. The forces on the neck go around the bathtub and the spring cavity, into the "wings" of the body and then shear back into the chunk of wood the trem is bolted to. There is a little of this with a conventional 3 pickup route, but, the standard route is stiffer and more neck load takes the direct path to the bridge and should have greater sustain. Tone is a very subjective thing. There's lots of ill formed opinions about what makes or destroys tone. Some people rail against glue as some kind of tone poison. Acoustic instruments are held together with glue, have their voices shaped with glued on pieces, and glue comprises a much larger part of their structural weight than even the cheapest solid body electrics. I haven't heard a chorus of people bemoaning their tone-less Martins. There are some pretty large variations in the tone of wood, within the same species, within the same log. Some chunks ring and others thud. If luthiers don't do controlled experiments, to isolate the effects of construction details from variations in their materials, then their result and their conclusions won't be definitive.

Ben, Those Totem guitars remind me a lot of Girl Brand: Tele shaped, very artsy... and they've both sold guitars to Henry Kaiser. Taking found objects and casting them in clear resin reminds me too much of "crafts" in the '70s and nautically themed restaurants (with shells and sand-dollars). I'm sure they're using the good "tone" resin. They look pretty cool. Mick, In that Byrd interview, he says: I thought Fender went to the bathtub route for economic reasons- quicker to route and interchangeable for all pickup configurations that use a pickguard. Yeah and other people swear that the bathtub is a tone killer. I don't think you're going to find concensus on any aspect of guitar design. I'm surprised Byrd doesn't advertise this detail on his website... he could call it the Jacuzzi-Route™.

I like creative hacks, clever DIY alternatives, and creative solutions. That said, I think you should find access to the tools you need or abandon your project. If you're going to attempt this with a hand held drill you're probably just going to waste time a lot of time. For this to work even as well as a cheap Chinese Bigsby knock-off it's going to require more precision than a hand drill. How are you going to cut and shape the metal? Hacksawing gets old very quick. If you're going to use aluminum, the shavings load up files really quickly. With just hand tools, you could make a working trem with a door hinge... but, what would be the point? Unique, but, cobby looking and doesn't work as well. Find someone who'll let you use their tools. It will make the project easier and increase its chances of success. If I were going to homebrew a Bigsby, I'd opt for a lost foam casting. For the critical holes, you could use bolts/tubes as cores, that the metal's cast around. There are lots of resources for making a DIY furnace. You can find lots of stuff on the web, too. Yes, it would be a lot of work.

The critical thing, if your pivots are multi-piece, will be getting the holes aligned. If the holes are mislocated or skewed, the pivot shaft won't fit. I think, at a minimum, you'd need a good sized drill press. If you're going to use rolling element bearings, think about how they're going to be retained. If they're cassette bearings (a complete assembled unit) they can be press fit into a precise hole. You can use circlips to hold them if you have machined grooves in the housing or on the pivot shaft. Also think about how you're going to make the arm and attach it to the shaft.

Buy a cheap tele bridge on eBay and whittle it up. A Bigsby changes the look anyway... get something that works. On the TeleModders website, I found pics of a lightly modded bridge and one with more extensive surgery.

So, what tools do you have access to?

Marzocchi, I'm old. I come from the time of 1" threaded steer tubes (before 1.125" unthreaded headset and oversized ball bearings). You didn't have to misadjust a headset to get index steering. I'm sure things have improved. I think you've got your nomeclature mixed. The "race" is the metal ring that has the surface the bearing rolls on. On a bike they get called "cups" and "cones", depending on their shape. It sounds like you're referring to the bearing cage, that separates the bearings and keeps them from contacting each other. Old motorcycles used to use ball bearings in their headtubes. It's pretty common to replace them with more durable taper roller bearings (like those used in modern production motorcycles). From the parts list, at the Bigsby site, they list needle and roller bearings... no balls.