Stepped Frets

[GuitarGuy]

well, Parker guitars uses a thin reinforcement of ccarbon-glass-epoxy reinforcement on both the neck and the fretboard... maybe that kind of idea would work?

if you could make a very precise wood carving, and put some composite over it, it might work on the warpage issues and such...

my 2c...

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Not quite, their fretboards on the Fly's are carbon, no wood, the frets are baked into the carbon laminate in an autoclave after being laid up in a mold, this is why they use SS frets, because it's near impossible to replace their frets so they just can't be something that wears out quickly.

A thin composite will be strong sure, but will do nothing in the way of wear resistance, Carbon cloth layed up will only be as wear resistant as the epoxy resin it's impregnated with. Most epoxy resins aren't that hard.

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You have a point. The epoxy would wear really bad. The only thing I can think of is adding frets lol. And we're now back to square one. Perhaps machined from another composite. Like some nylons can be more wear resistant than steel albeit about as expensive too. But then you run into the cost of machining if you dont have the facilities.

I think I know why the idea was abandoned!

[psw]

I think I know why the idea was abandoned!

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The bond history is really interesting. What happened is they bit off a lot more than they could chew and went silly with the total concept!

First, too many cooks in the production concept. They did have trouble with shrinkage and such, but had already showed it off at the trade shows and had taken a lot of orders. As a consequence, a lot of "bonds" actually have milled aluminium boards as they struggled to actually get production up on the epoxy ones due to technical difficulties. I believe they overcame these problems but the company went under pretty quickly dispite sizable government loans.

They also put so much electronics in it that it needed to be remotely powered (could'nt run off batteries). Basically if you look, there is a display window that faces up towards the player. This had a digital display of the volume, tone and pickup selection. All of these things of course can be arguably better adjusted and displayed with conventional switches and knobs with numbers, so for all that, they achieved nothing but to add to the expense.

The stepboard though, was originally used on handmade acoustic guitars by Andrew Bond and worked well as a concept of it's own (though examples are very rare). It was quite ingenious. The 'board was as thick as a conventional fretboard and was bolted to the neck. The bolts are hidden below the fretboard markers. The idea was that you could simply dig out the 'dots unscrew the board and replace it. Smart.

That's not what I'm proposing though. I'm suggesting a very thin board (little more than the exposed height of a fret), moulded directly to the wood. Aesthetically, I really like the idea of it being glass clear and seeing the neck through it. Practically, there may be better wearing materials. For instance, graphtec nuts and saddles are graphite impregnated epoxy and I've been able to make compounds of epoxy and graphite myself that have similar qualities (very black and slippery). Perhaps kevlar or other such materials would be of interest. It'd be a little heavy, but fine stainless steel powder could also be used to make a composite that would be exceptionally hard wearing.

I don't anticipate, given the small mass of my proposal, that shrinkage would not be that great, especially given that the majority of the compound is, in fact, a very stable glass. The amount of epoxy would be very,very small in comparison. You could add a sub layer of carbon fibre to add stiffness but then, you probably wouldn't need it with a conventional neck so there's no need to get high tech about it.

Speaking of which, they (the "bond" guitar commitee), built their factory (in scotland) right next to a carbon fibre manufacturer. The government and the band the eurythmics put a lot of money into it to help with employment and innovation. The weather even got the best of them but most telling of all, the carbon fibre made next door was completely unsuitable for the task and they ended up having to import it. The whole thing was a comedy of errors that, I believe. scuttled the creator's (the real Andrew Bond) contribution, that of the stepped board. He suffered greatly from the experience and died not that long ago.

I really apreciate LGM's contributions and that he seems to have toned down his often forthright opinions. There's nothing quite like a great fretted fretboard but I still think, on a production basis, fretting and radiusing boards are labour intensive and the wire's not that cheap...but hey, this is not going to replace anything. Fender though made great inroads with the bolt on neck concept and revolutionised guitar construction in the process. And electric guitars, and the guitar in general, IMHO is actually a very young instrument still under development. Also, There just seems to be something appealing about the idea that really struck a chord with me (no pun intended). But, I'll make my opinion clear, I'm not at all suggesting that this is a better scheme than traditional frets. Properly executed though, I don't think it's going to be worse.

As for the mold, I've got some ideas. I think that some posts have the idea that the original needs to be a working model. It doesn't, It just needs to be very acurately shaped. I'd be thinking (when I get out of hospital) bending a smooth compound radius over say a bent PVC pipe. Over this I'd very acurately, literally glue the steps at the right intervals. I'd then carefully shape with modeling clay the shape to these steps. Removing it from the radius pipe I'd then back fill the curve at the back. Then, after cutting it to shape, make a silicone mould and do a epoxy cast. Take this out and highly polish and work it over to correct any defects. This then is the master from which another mold is made (something like Gel-Flexis reusable). The mold would be put steps down and supported flat. The neck blank would then be pushed down (probably in a vacuum bag) onto the mold and the compound would conform to any irregularities. If it is able to be glass clear, "inlays" could also be moulded in with the process. The board and possibly the peghead and nut slot could be done in one pass and a router be guided along the moulded edge to cut out the shape and trim any excess that would be squeezed out along the edge of the 'board.

Now, model making and mold construction is difficult and time consuming but the end result, once done right, would be a very efficient and acurate way of producing the thing. Not better. Different sure. As good as a fine fretboard like LGM makes, possibly (maybe not that good) but surely better than your average cheapo guitar.

Anyway, great to have you guys come in and take up these ideas for discussion, it's exactly what I was hoping for...cheers

pete

[tirapop]

I think you've got the right idea about using "tiles" for each fret segment and build a male tool (no sniggering) to take a cast from.

If I were you, I wouldn't be bending segments over a PVC pipe. Take an existing radiused finger board and chop it up. Instead of cutting perpendicular to the fretboard surface, cut it at the slight angle you intend the segments to inclined at. The cut edge defines the fret surface.

You can then cut flat steps, at that same angle, in a board and load the tiles in. You can shim under each tile to get them all at the same height. You can use putty/bondo to radius the corners where the tiles meet.

I don't think you want to use flexible molding compounds. That stuff is great at making facsimiles... not dimensionally accurate parts. If you apply any heat or pressure on them, they'll squish or distort. You need hard tooling.

Materials are going to be the hard nut to crack. It's one thing to speculate about the durability of different materials you can mix into epoxy, but, to actually get them to work is another thing. You can buy off the shelf metal filled epoxies and they aren't wear resistant.

Little glass balls will be difficult to wet out, without trapping bubbles that weaken the structure. It might drive you to more fluid epoxies that have poorer structural properties.

Then there's the question about how well the epoxy will hold onto those durable little particles as they are constantly worked, exposed to sweat, finger oils, UV, etc. You also want to avoid the possibility of hard little particles in a softer matrix, that gets eroded away, turning itself into something like sandpaper.

Kevlar has excellent abrasion resistance because the fibers have high toughness (they stretch without breaking) not because they're hard.

I'm not trying to be negative. I'm an aerospace engineer and I get to work with exotic materials. Lots of materials have great initial promise, but, have some shortcoming that makes it unsuitable or limits its usefulness. I'm not saying there isn't a suitable material out there that you can process in your home shop. Finding it is going to be the most difficult part of the project.

[LGM Guitars]

I'm not sure I would say I've toned down forthright opinions, I've just come many times from the been there done that school.

Personally, in thinking about this concept more and more, my biggest concern is in that if you do not use a hardened steel, it will eventually wear, and with no recourse for maintenance, it becomes a disposable piece.

Out of curiosity, yesterday I took a carbon rod (autoclaved, used for wing spars in the jets I fly) and started running a couple guitar strings under tension back and forth over the edge, it didn't take long before there was noticable wear.

So, my thought even on using a pressure molded carbon probably won't work.

There are no nylons that will withstand a sharp pressure point like a string, there are delron's, teflons, nylatrons etc that are very wear resistant for something such as a bushing, but even those wear, and that is with large turning surfaces, not typically a direct pressure from a tiny diameter like a string.

As tirapop said, Kevlar is very wear resistant, but again you run into the problem of the epoxy used to impregnate it.

What I keep fighting with is, when it does wear how do you maintain it.

Frets are dirt cheap, when buying in bulk (for production, which is comparing apples to apples in this case as if you are considering making molds it is only realistically viable for production work) is about $4 per neck. With a radiusing jig it takes all of 5 minutes to radius a fretboard after a 5 minute slotting job.

Just like making your mold, it all comes down to having the right jigs and tools for the operation. I personally don't see molding a fretboard with steps to be any faster than using fretwire and a wood board, and I sure don't see it being cheaper, in fact, I would probably estimate that a laid up composite board would be double the cost of wood and wire in the end. (not including the cost of making the molds)

Again, for personal experimenting, I'm all for trying new things, but as you said, there was a company who tried this and went under. The concept might be great, but many things are perfect in theory, flawed in reality.

I don't say any of this to be negative or be a prick, but I've made many molds, I've used carbon's, kevlar's, and other composite materials many times. To make a proper mold is an expensive and time consuming process. I've worked with the materials extensively and just feel that you will end up with a product in the end that will not hold up to your expectations the way you'd like it to.

Is there a better solution than frets in wood? probably, but I don't think it will be found with current composite materials at this point.

The only thing I could think of working, is if you did your lay up, and at each "peak" of the steps, you had a piece of hardened steel layed into the composite material where the string will actually hit, but then you're right back to basically the same concept as frets

[psw]

Thanks a lot guy's, and there is absolutely nothing negative in your replys, opinions and obvious experience. When I have a little more time, I'll dig out the stats from the glass fret patent. They were extensively tested along side standard frets and epoxy for wear and the results were pretty impressive. In fact I was thinking of duplicating such a test on some materials by getting a little motor to continually fret and rub a string at tension onto a test "step" and seeing what happens.

The gibson patent as I remember has this very notion of a steel piece at each step and then backfilled. As the step idea is, in my opinion, for the purpose of construction, not performance, standard fretting would come way ahead in everyway to this idea!

So, before I get any where near building the real thing I'll really need to do some work on the composite qualities.

I'll also need to do some more thought on the repair / wear issue. How do Parker refret? Do they assume their stainless steel just wont wear out, ever?

Very valid points but not enough to scotch the idea but I will need to be kept in check as conventional fretting may indeed be better in everyway...I might just get carried away with the idea. I know for a fact though, that conservative as we guitarists are, it wasn't the stepped frets that let the "Bond" guitar down. If only the originator had been able to explore the idea further without all the other crap that was thrown into it from a committee of others seeking funding and overambitious with their production and other motives!

anyway, I'll check back when I can

pete

[Pr3Va1L]

what i read is they basically remove the composite from that area and refret it... (don't ask exactly how...)

but to actually need a refret on SS frets, you'd need to be playing a damn lot

[psw]

OK, now that I'm home again I can access a bit more information...

So firstly here's a bit on that patent...first a link to the Patent

GLASS FRET PATENT 2003

(BTW to get images you may need to download a special viewer, I think I've Infraview, check out the USPTO site for a link to the free download)

Here's the initial abstract (the patent is 46 pages long plus drawings!) so I hope this is of help:

United States Patent 6,657,113

Herman December 2, 2003

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Molded fretboard and guitar

Abstract

A molded fretboard according to the present invention has integrally molded frets. The frets are composed of a molded mixture including a higher proportion by volume of glass beads than resin, thereby providing abrasion resistant characteristics that are the same as or better than conventional steel frets. The glass beads are compacted such that each glass bead is in contact with at least one other glass bead. The fretboard itself may be composed of this molded mixture, providing increased abrasion resistance to the top working region of the fretboard, and an entire molded guitar may also be produced in accordance with the invention. A method of installing a fretboard on a guitar is taught which ensures the linearity of the fretboard, regardless of the curvature of the neck. This method provides solutions to the problem of having a bowed neck and the problem of having a non-straight fretboard simultaneously.

OK, now I'll see if I can pick out some other choice bits...

"Steel" fretwire is made of a hard nickel steel alloy, sometimes called "nickel silver". Although the fretwire used in frets is subject to wear by constant string friction during usage, it can last several years before replacement is required. Fretwire replacement and alignment costs for an entire set of frets on a fretboard can be quite costly.

The requirement for high precision in fret construction and placement, together with the high cost of replacing worn frets are some drawbacks of the use of fretwire.

Several known arrangements exist which have attempted to overcome some of the drawbacks inherent with the installation of fretwire on a conventional wooden guitar fretboard. In one such arrangement, a fretboard and frets are machined with a computer milling machine. Such an arrangement, although able to produce a fretboard and frets with shapes and dimensions of high accuracy, is not well suited to the low-cost production of a fretboard and frets, thereby imposing a barrier with respect to its practical use. Other known arrangements employ the concept of having a molded fretboard (and/or molded guitar comprising that molded fretboard) having integral frets, thereby reducing concerns relating to the placement and preparation of frets at particular positions on the fretboard. Examples of patents making reference to a fretboard for a guitar, with the fretboard having integral frets, include: Canadian Patent 1,080,522 issued to Bond on Jul. 1, 1980; U.S. Pat. No. 5,072,643 issued to Murata on Dec. 17, 1991; U.S. Pat. No. 4,290,336 issued to Peavey on Sept. 22, 1981; and U.S. Pat. No. 5,033,351 issued to Nomura on Jul. 23, 1991.

However, there are still drawbacks relating to the above-listed patents. Although some known arrangements, such as those in the Bond patent, appear to discuss the concept of providing integral frets that have good wear characteristics as compared to steel frets, there is little indication as to how these characteristics are specifically obtained. There are references to the use of glass fibers in Murata and a glass-filled neck in Peavey. However, the purpose of the glass fibers, as described in Murata, is to provide strength, and not abrasion-resistance. Peavey does not specifically mention how frets are fabricated, what they are made of, or how they are integrated with the finger board.

The use of glass beads and resin in a musical instrument is taught in U.S. Pat. No. 5,911,168 issued to Enserink on Jun. 8, 1999. However, the glass beads as described in Enserink have a low density and are not used for the purpose of providing strength or preventing abrasion but for the purpose of decreasing overall weight. These glass beads would be buoyant and are not suitable for forming a surface layer on a fretboard. Additionally, the wall thickness of the glass beads is thin (1-3 microns) and is unlikely to provide adequate abrasion resistance, in that the bead wall would most likely collapse under any significant pressure exerted thereon.

Therefore, there is a need for a guitar fretboard that can overcome at least one of the drawbacks of the prior art arrangements.

Fret wear abrasion test results

The fret heights on any fretboard, regardless of the curvature of the fretboard, will decrease if subjected to wear, which results in a deterioration in sound quality due to buzzing. In specific tests that were conducted (with results extrapolated to normal usage), it was found that conventional steel fretwire would wear at a mean rate (non-linear) of approximately 0.001-0.002" per year (e.g. 1st & 2nd fret at the 1E string position) with an average guitar usage of approximately, 1 hour/day. A total wear of 0.005-0.007" will typically render the guitar sound "poor" and require replacement of fretwire. Consequently, a guitar fretboard might have a practical lifetime of about 7 years. Typically, an acoustic guitar can tolerate a total wear of up to 0;003-0.004" before sound quality deteriorates sufficiently to require fretwire replacement. Although these results were obtained via particular wear tests, they were used in subsequent analysis as a model of standard wear patterns for steel fretwire.

Frets were tested for abrasion-resistance on an apparatus that was specifically constructed for simulating the impingement of a guitar string on a fret. With reference to FIG. 2, this apparatus consisted of a motorized rotating cam-wheel 210 which would depress a single guitar string 220 onto a test fret 230 (a cross-section of which is shown in FIG. 2) and cause abrasion simulating the depressing action of a player's fingers. The test fret 230 was mounted on a supporting block 240. A treble string of 0.012" diameter was chosen since it typically represents the string (of that approximate diameter) that causes greater wear than other strings of larger diameter. The length of the string (scale length) was chosen at approximately 21" and by tuning it to a treble E note (330 Hz), the string had a tension of approximately 23psi. The total deflection 250 at the cam-wheel 210 was approximately 0.250". The rotating cam-wheel 210 was able to produce 3.3 deflections per second. Although the simulated action of the tester may not be `exactly` representative of finger pressure and motion, all tests were conducted as being `relative`, that is, by comparing tests of the resin frets against similar tests of steel frets.

Two types of fret abrasion were simulated and tested. FIG. 3 illustrates a side view of a test fret 230 and a string 220, and illustrates a vertical compression/abrasion test in accordance with the tester of FIG. 2. FIG. 4 illustrates a side view of a test fret 230 and a string 220, and illustrates a sliding abrasion test in accordance with the tester of FIG. 2. For the vertical compression/abrasion simulation, the string 220 followed a string motion path 310 and string impinged at 90.degree. to the fret 230 as shown in FIG. 3 and formed a groove 320 as a result of the forces of compression and abrasion. For the sliding abrasion simulation, the string 220 followed a string motion path 410 and impinged on the fret 230 at an angle of 45.degree., sliding along the fret 230 for a distance of approx. 0.060-0.125", and formed a wider groove 420 as a result of sliding friction as shown in FIG. 4. In the former case of vertical abrasion, the width of groove 320 was similar to (or slightly larger than) the width of the string 220, which was 0.012" diameter. In the latter case of sliding abrasion simulation, the resulting width of groove 420 was approximately 0.060" as shown in FIG. 4. In all cases the maximum depth of the worn groove was measured microscopically. In each of FIGS. 3 and 4, the dotted circles indicate subsequent positions of the string 220 along the string motion paths 310 and 410, respectively.

Three types of frets were tested; i) a reference steel fret mounted on a supporting block, ii) a fret fabricated from epoxy resin-only (no glass beads), and iii) a fret fabricated from compressed glass beads (approximately diameter 80 microns) and bound together by resin. The recorded wear for vertical abrasion of the all frets is shown in FIG. 5, where each fret was tested for 92 hours representing approximately 1 million strokes. As expected for a fret of semicircular cross-section, the wear curve is near-exponential since, as the groove becomes deeper, there is more surface area to abrade. After 92 hours of tests, the steel fret had a wear groove of 0.0028" depth while after 96 hours, the beads/resin fret had a groove depth of 0.0020". The fret fabricated from resin-only had wear of 0.004" after only 12 hours of testing. Comparatively, the frets fabricated from resin-only (ie. a variety of epoxy resins) wore more rapidly than the steel frets by a factor of 4-10X, while the beads/resin fret had similar wear characteristics to that of the steel fret.

The recorded wear for sliding abrasion of each of the types of frets is shown in FIG. 6, where each fret was tested for 36 hours representing approximately 400,000 strokes. The resulting curves clearly show that this type of sliding action causes greater wear to a fret than that of vertical compression/abrasion. After 36 hours of tests, the steel fret had a maximum wear depth of 0.0048" while the beads/resin fret had a maximum wear depth of only 0.0024". The resin-only fret had a wear depth of 0.0088" after only 12 hours of testing or approximately 3X that of the steel fret. The beads/resin fret typically showed 1.5-2X less wear than that of steel frets demonstrating the suitability of this improved design.

Following the conclusion of many similar tests, it was found that most epoxy resins/plastics would wear approximately 3-10 times faster than steel fretwire, with up to 2/3 of the wear potentially occurring during the first 1/3 of its usage. Although easily manufactured, the use of these resins/plastics would not be practical since the frets would require replacement in 6 months. One of the most durable resins, polyester resin, known for its `hardness` (it is used to coat piano surfaces), was tested. This polyester resin was found to wear 3 times faster than conventional steel fretwire. Its use would still be impractical since frets made of polyester resin would require replacement within 1 year. Moreover the fret of polyester resin was also brittle and therefore is easily chipped or shattered on impact, further rendering it impractical as a fret material.

As a result of these studies, it was determined that resins/plastics are not suitable as fret materials due to their poor abrasion-resistance characteristics, which would explain why these materials are not seen on commercial guitars. Furthermore, it would not be practical to mold integrally a plastic fret in a fretboard since the frequency of replacement would require replacement of the entire fretboard and not just the frets. An example of an ideal abrasion-resistant fret would be one that is made of glass. However, glass frets would be also be difficult to manufacture and install, and would be brittle and susceptible to chipping and breakage. As can be concluded from the above data, the fret with a mixture of glass beads and resin was found to provide the best wear characteristics of those materials tested. Following this result, it remained to be determined what particular materials could preferably be used for this mixture, as well suitable methods of preparing and pouring the mixture.

I should probably remind people that in this patent they are talking about molding conventional "frets", not "steps".

I'll now see if I can get a bit of info on some of the stepped fretboard idea...

OK...look what I found, the bond patent...

BOND GUITAR PATENT

Here are the pics from page one of this thread to remind you guys of the concept:

So here's the abstract:

United States Patent 4,064,780

Bond December 27, 1977

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Abstract

A stringed instrument having a fretboard with a sawtooth surface profile with the crests of the teeth in the normal fret positions. Optionally the instrument may have a rotatable nut of generally cylindrical form having a plurality of annular grooves therein, one groove for each string of the instrument. The nut is so mounted or the grooves are so shaped that on rotation of the nut, the heights of the strings from the surface of the fretboard are varied simultaneously.

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Inventors: Bond; Andrew (38 Courthill Road, Parkstone, Poole, Dorset, EN)

Appl. No.: 605502

Filed: August 18, 1975

Here is the basic description of the concept and the inventer's reasoning for it's advantages. I had not realized that he also had an adjustable nut height concept as this didn't go into production but I've included it here since it was a part of the original patent and looks like a pretty cool idea too!

Description

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The present invention relates to stringed instruments and particularly to guitars. For convenience of description reference will be made to guitars, but it is to be understood that this term is intended to include other stringed instruments.

A guitar comprises a body, a head and a neck interconnecting the head and body. A plurality of frets are mounted transversely at spaced intervals along a fingerboard or fretboard secured to the neck and extending over the surface of the sound table to the sound hole. Strings extend from a bridge, over a saddle, along the neck and over a nut mounted at the junction of the neck and head to separate machine heads which are used for retaining and tensioning the strings.

When a guitar is played, the strings are pressed down by the fingers towards the fingerboard until they meet the frets and/or fretboard so that when the string is vibrating it will produce a note of the required pitch or frequency. This note should be accurate to within an error which the human ear cannot detect and should be free of spurious noises (e.g. rattle and buzzing) which are not directly related to the production of the required pitch or frequency and its harmonics.

The main factors which affect the notational accuracy and the amount of spurious noise are as follows:

1. The height of the strings above the fretboard.

If the height of the strings above the fretboard is too low, the vibrating string will knock against the frets between where it is being pressed down and the bridge; this produces an unwanted buzz or rattle. If the string is too high, the time taken to press the string down onto the fretboard will be undesirably long and it will make the guitar slow and difficult to play. Also the string will be stretched when depressed to the fretboard which will result in an increase in tension and a consequent raising of the pitch of the note.

If the string is plucked gently as in finger picking, the minimum height of the strings may be less to avoid buzz and rattle, than if the strings are being strummed when they will vibrate more strongly.

2. The longitudinal flatness of the fretboard.

The longitudinal flatness of the fretboard is important because it affects the minimum height of the strings than can be used without rattle. If the fretboard curves or twists along its length the height of the strings is determined by the minimum height above the highest points of the curves or twists, and because of the irregularity it is much more difficult to play.

To prevent the fretboard from curving, many guitars have a metal rod or "truss rod" set at a slight angle to the fingerboard inside the neck to compensate for the upward pull of the strings. In practice the truss rod needs constant adjustment and is only partially effective.

3. The surface profile of the fretboard.

The surface profile of the fretboard affects notational accuracy and also the ease of play. When a string is pressed onto a fret, which protrudes from the fretboard, it will produce one note, but if it is pressed down harder onto the fretboard behind the fret, it will be stretched over a longer distance and the resulting increase in the tension of the string will cause the pitch or frequency of the note to be raised by an audible amount.

Therefore it is desirable to have as low a fret height as possible, but the lower the fret height the faster the fret will wear out.

4. The Position of the fret relative to the scale length.

This determines the frequency of the notes obtained when the guitar is played; if the frets are wrongly positioned the guitar will not play in tune.

As well as having the greatest possible notational accuracy and the minimum of spurious noise, a fretboard should have as long a working life as possible maintaining these characteristics and it should also be easy to play and offer maximum comfort to the player.

Conventional fretboards are made from hard wood, with frets of nickel-silver or other material. The neck is made of wood and the truss rod is metal. The nut is plastics or bone, with grooves cut in the top for the strings, and it determines the height of the strings above the fretboard in conjunction with the bridge saddle.

The disadvantages of this design are as follows.

The height of the strings above the fretboard is permanently fixed by the nut, and only slight alteration can be obtained by altering the saddle height at the bridge. This means that the string height is best for either finger picking or strumming, or else it may be set for Hawaiian style (bottleneck) where the strings should be about a quarter of an inch from the fretboard and also in a flat plane rather than following the curvature of the fretboard. Therefore the player is restricted to playing in the manner for which the guitar is set or must settle for a compromise.

As the neck and fretboard are made from wood, and are being subjected to the pull of the strings, they tend to bend or twist and therefore cause the height of the strings above the fretboard to increase, which is undesirable. Also, as the humidity and temperature of the wood changes, so further stresses are set up and increase this effect. Due to these changes, although the fretboard may start off straight, the straightness does not last and usually needs lengthy repairs.

Further the fret material is, of necessity, a soft metal and therefore it is subject to a high rate of wear. As the frets wear so the profile flattens and produces a condition wherein the frequency can increase by a quartertone to a semitone in the pitch of a note selected.

In one aspect of the present invention, there is provided a fretboard for a stringed instrument, the fretboard having a sawtooth profile, such that the crests are in the normal fret positions. The more vertical faces of the crests face towards the body of the guitar and the opposite face slopes back to the base of the fret behind. This is in order to reduce to a minimum the frequency deviation caused when the string is fretted, and also to reduce the opposition to the fingers when the hand is being moved rapidly up the fretboard.

In the present specification it is to be understood that by "sawtooth shape" is meant a substantially triangular shape having its base formed by the body of the fretboard, a relatively short side inclined substantially at right angles to the base and a relatively long, planar side extending from the top of the short side to the bottom of the short side of the next following ridge in the direction of the head end of the fretboard.

The fretboard should preferably be made of a light, strong substance with a hard surface, so that it will not wear in use, nor bend or twist under the tension of the strings. Suitable substances may be high impact plastics, magnesium alloy, aluminum alloy with a hard anodised surface, plastics or aluminum alloy with hard strips set into the crests of the ridges, e.g. tungsten carbide; or any other suitable substance which may be either machined, cast, moulded or a combination of these. The front face of the frets may be marked in a different colour of hard anodising or by any other method for ease of fret identification.

The fretboard may be screwed or glued to the neck in the conventional manner. If desired, an elongate stiffening bar may be formed in the underside of the fretboard, being located in a groove formed in the neck of a guitar to which it is fitted.

Further the elongate stiffening bar may be made in a male dovetail form, and the slot in the neck may be made in a female dovetail form. If the female is tapered slightly at the body end of the neck the fretboard may be attached to the neck simply by slotting the male dovetail bar into the female dovetail groove formed in the neck and tapping them tight, thereby forming a friction fit.

If desired the fret may be of convex shape as viewed in transverse cross section.

Further, the neck may be formed of plastics, glassfibre, or other synthetic material that would have the advantage of increasing the strength whilst not being affected by humidity or age, or the neck and fretboard may be made as a single unit. A wooden neck would also be suitable provided that the neck and fretboard together are designed to accept the total string load.

Apart from the simplicity of fitting such fretboards, or replacing them, the working life should be considerably extended due to the surface wearing at a slower rate than conventional frets. Also the position of the frets may be determined with a precision accuracy which will not change with wear. The fretboard with an elongate stiffening bar will maintain its original flatness far better than conventional fretboards and will not be subject to changes due to humidity or temperature as much as conventional fretboards. The truss rod will not be needed, so adjustment and manufacture should be simplified.

Due to the cumulative effects of these factors, the height of the strings above the fretboard may be kept to a minimum for any mode of play. This will improve both the notation and the ease of play.

The accuracy of the fret positioning and the reduction in notational deviation caused by the string bending over the fret when it is being played will make any inaccuracy in frequency inaudible.

In another aspect of the present invention, there is provided a nut for a stringed instrument, the nut being of cylindrical form with annular grooves therein through which strings extend in use, the nut being so mounted or the grooves being so shaped that by rotating the nut the height of the strings above the surface of the fretboard, is varied.

Preferably the sides of the grooves diverge in a radially outwards direction to prevent the strings vibrating against the sides thereof.

Preferably the shape of each groove is that of a plane spiral so that the scale length is not varied when the nut is rotated about its longitudinal axis; therefore any height of the strings above the fretboard can be selected by the player to suit the mode of play.

Further, by having slightly different dimensions on the plane spirals, the strings may follow the curvature of the fretboard in the low position suitable for finger picking or strumming and in the high position may be in a flat plane suitable for Hawaiian or "bottleneck" style.

The cylindrical nut may be rotatably mounted in brackets at each end or in any other way so that it can rotate. It may be driven by a lever, or a worm gear and cog mounted at either end. The cog may be made as an integral part of the cylinder between the grooves, with the worm gear coming up through the base of the neck so that it meshes with the cog. This would have the advantage of keeping the weight down to a minimum, and it would reduce the change of accidental damage and make the drive mechanism as compact and efficient as possible.

A device similar to the cylindrical nut may be used in place of the bridge saddle, with arrangements for longitudinal displacement and adjustment.

In yet another aspect of the present invention there is provided a stringed instrument having a fretboard with a sawtooth profile and an elongate stiffening bar underneath, and a cylindrical nut rotatably mounted and adapted to vary the height and plane of the strings above the surface of the fretboard as the nut is rotated. If desired, the mounting for the nut is formed as an integral part of the fretboard.

And here's a little more that I hope puts to rest the idea that the stepps will be hard to slide along

The surface of the fretboard must be hard and smooth so that it is pleasant to play and wear is kept to a minimum, e.g. hard anodising on aluminum, or high carbon steel strips may be inserted into the crests of the ridges.

By using the sawtooth shaped profile, of the above construction the height of the strings above the fretboard may be permanently kept at the lowest and hence the fastest level regardless of normal humidity or temperature fluctuations. Notational deviation will be outside the range of human hearing, string wear will be reduced due to a greater area of string being in contact with the sawtooth profile, which allows the stress to be distributed over a wider area of both string and sawtooth fret; there will also be less opposition to the players fingers when moving swiftly up the fretboard

So there's some more info...more than I thought I'd be presenting but patents can be a pain to get to the good stuff so, since I read them I thought I'd put the good stuff here in full to fuel the discussion.

There are two separate ideas here...the stepped board discussed above and the glass fret idea of the first. My proposal is to combine the two ideas. I have to say though, that LGM may well be right about the practicality, economic and long term viability of conventional fretting techniques...he has put forward some very persuasive arguments. I'll really have to look into the cost of the materials (forget about the molding etc for the moment) as they may well out price the concept and benifits...we'll have to see when I get a bit more into the testing.

Anyhow, if nothing else it's food for thought...let us know what your thoughts on all this are

pete / psw

Edited April 28, 2005 by psw

[onelastgoodbye]

Ok, that's your longest post yet

The stepped board concept is interesting but I'm really not sure if it's feasible without high-end machinery; not so much because of the shape of the board, but because of the materials involved. I think you're basically looking at a complete metal board or something with steel inserts (and maybe some exotic nasa stuff). Now, epoxying from a mold is 'easy' enough, but adding metal inserts into that proces, whilst keeping within tolerances etc... might wanna build a cnc first

(actually it just so happens we had a demo at school this week featuring laser-welding...that stuff is soooo cool and would be perfect for the tiling idea).

What I'm basically saying is that the cost of research and production might not weigh up to the benefits of the final result.

That said, the hard way is the fun way, I'm all up for it!

That cilindrical nut is intrigueing, but I'm having a hard time visualising it..

[psw]

Not bad post eh...mind you it's mostly cut and paste

I'm hearing you Tim. I think you may have missed the glass fret idea. The idea is to have a high concentrate glass/epoxy mix for abrasion resistance so there would be no need at all for any metal inserts at all. Furthermore, the results of the inventor's testing indicates wear is significantly better than that of conventional metal frets. Combine that with the stepped fret idea that spreads the wear over a larger area, and you might find you have a different perspective on the concept.

Hate to say it, but you might need to read that post again to get the gist!

pete

[GuitarGuy]

Ok, that's your longest post yet 

The stepped board concept is interesting but I'm really not sure if it's feasible without high-end machinery; not so much because of the shape of the board, but because of the materials involved. I think you're basically looking at a complete metal board or something with steel inserts (and maybe some exotic nasa stuff). Now, epoxying from a mold is 'easy' enough, but adding metal inserts into that proces, whilst keeping within tolerances etc...  might wanna build a cnc first   

(actually it just so happens we had a demo at school this week featuring laser-welding...that stuff is soooo cool and would be perfect for the tiling  idea).

What I'm basically saying is that the cost of research and production might not weigh up to the benefits of the final result.

That said, the hard way is the fun way, I'm all up for it!

That cilindrical nut is intrigueing, but I'm having a hard time visualising it..

←

I still dont really see the advantage over a scalloped fretboard? While the idea still is cool.

[psw]

Well it's no advantage though you could make a wicked scalloped version. Actually the inventor is suggesting the opposite to scalloping. Because the string can't be bent over the fret as your finger hits the fretboard directly behind the fret he suggests that intonation is improved. Furthermore, that a lower action can be achieved.

The main purpose to my mind in my melding of the two ideas is to spread the wear over a wider area than just the fret top and to give the glass/epoxy, or whatever it's made of, cast "frets" adequate support. The fret's aren't lumps stuck to the fretboard but intregal to it providing support against wear and damage not addressed in the first patent.

Whether it's got any legs as a practical or worthwhile exercise is certainly up for debate. It would certainly look cool. But economical or practical...or better or equal....very much in question. I'm prepared to do a little experimentation with some materials and I'd love some more suggestions.

An idea I had was to use teflon or graphite in the mix to provide a slippery wear resistant surface...it's something to consider in addition to simply making something harder than nickel alloy.

Anyway, I hope I did't bamboozal or overload anyone with my super-post.

As onelastgoodbye alluded to, I'm renown for long posts!

So I'll finish this one here...but, I'll try to get some of the patent images up to fuel the imagination in the near future!

psw

[psw]

Well this is a little off topic but here is an illustration from the Bond Patent that I was able to isolate of the adjustable nut idea. Interestingly it takes up a large part of the patent yet never appeared on the actual guitar. But here it is all the same:

enjoy

pete

[mushy the shroom]

Sorry, I didn't have time to read through the patent. What does the cylindrical nut do? Adjust nut action? I guess that'd be pretty cool, if a bit unwieldly. Anyway, the whole stepped-fret design appeals more to me than normal frets, but I'm sure it would be ultimately harder to make for a one-off type of build (although, much cheaper for a factory run, if it's moulded). Glass frets sound (kinda a pun there) great, and I'm sure you could do some neat stuff with LEDs and whatnot. I'm not very technical on the ideas, but it seems to me like this would be better if you could get it CNC machined. The initial cost for a one-off is pretty steep (what with all the programming and figuring out the fixtures), but for each subsequent piece, the price is significantly reduced. If you're really bent on moulding it, it would be wise to CNC a multiple use mold, as hand-making one (even if you're going to "trade-up" the type of material you want to work with), would be very innacurate.. even with the finest of measurements.

[psw]

Well Ryan

There's quite a few technical hurdles to overcome. I've just been lookin in my workshop and the glass filler I have are actually hollow sphere's so perhaps not what's required. They're used in boat building because they create an increadibly smooth and light fairing material when mixed with epoxy, but I'm not sure about wear. I'll give it a go all the same for the sake of it, just to test out the principle, but more and more the concept seems to be a little over the top for just a few instruments!

The nut, I've just included as it was a little hard to visualise from the description. Basically it's a means to adjust the nut height with the turn of a tuning like key. Not something that there would be a lot of call for as the whole guitar would need to be retuned. Fine adjustment of the nut would be kind of cool to aid in setting up but something simpler and a little more discrete is probably in order.

The idea of stepped frets is what is of interest here. I saw in a part of one of the patents (perhaps the first one) that one intension was that the fingerboard and frets was moulded perfectly flat (albeit radiused) and glued to the neck while it was strung up to tension (ie with the strings on) and the truss rod adjusted. The idea would that, for that guage of strings, it would be "perfect"!

Anyway, it makes a discussion point but I'm now thinking that a good methodical method of conventional fretting is probably going to win hands down...but I'll play with the idea a little more I'm sure before I concede defeat.

pete

[Sparky]

As for materials, I know UHMWPe (ultra high molecular weight polyethelene) has amazing wear characteristics and is fairly hard. It also has a very low coefficient of friction, especially when metals is sliding on it, so it would feel fairly slippery, ...not sure if that would be a good thing.

I would look into some polymers used for bearings (such as UHMWPe) since they have great wear characteristics and low coefficients of friction. Of course, im not sure how easy it would be to adhere the fretboard to the neck if this material was used.

Another thing to look into is coatings...there are many metal (and even polymer based) coatings that will greatly increase wear resistance on a part.

All in all, it seems like a really hard thing to make in such low numbers...Die casting seems like the best option for this if you wanted to use a metal, but the initial costs are huge.

This seems fairly difficult to machine on a mill...it really looks like casting would be the best way to create it. You basically need a material that has a higher hardness rating than your guitar strings. Molding one entire piece seems very difficult...what about some metal inserts, say a 1/4" wide with a cheaper material inbetween? Maybe anodized aluminum or Ti-nitride coated steel inserts...sounds fun to make as long as it isn't my money being spent.

[tirapop]

It looks like that adjustable nut is meant to adjust height, with a cam surface that the string rides on... is that right? Seems like you wouldn't be able to change the height without changing the scale length/intonation. A radiused fretboard would make things really complicated.

If you look at anti-wear coatings avoid things like Nikasil or D-gun. Coatings like that use a very hard ceramic particles in a softer metallic matrix. These can be very abrasive... think about it, diamond hones are wear resistant diamond particles in a durable matrix.

[psw]

thanks for the input guys...

I dont think slippery would be such a bad thing as long as there's a way of sticking it to the neck! I particulatly like the feel of those graphtec saddles...I'll have to check their patent to see what that is.

The nut idea is cute but a little off topic, just showing what it was. More was made in the patent of this device than the stepped board. There may be a way of making a mold and have some kind of coating that resists wear and could be recoated (say when changing strings) to extend it's life.

I think once you get inserts invoved, your really just talking about frets aren't you. I'm not necessarily suggesting that the stepped board would be better than a quality fret job so I kind of discount these notions.

The way cheap guitars are being made in asia today, it's often cheaper to buy a brand new cheapy guitar complete to get a part like the neck than it is to buy a cheap neck to do it yourself.

Anyway, if you can give me some leads to how I can obtain coatings or materials (like solid glass powder beads) we can do a bit of a cost / benefit exercise on the idea.

I think though from the response to the idea, there just seems to be something attractive to the concept. Perhaps it's just the attraction of the new and different.

psw

[psw]

OK, so I was checking out this router fingerboard radiusing jig idea...

ROUTER RADIUSING JIG

Can anyone see a way of making some kind of jig that could route the steps on a wooden fingerboard without getting all CNC on me?

It maybe that a thin glass coating that could be recoated or maintained in some way, or a routable material other than wood that's wear resistant may be the way to go rather than molding as a concept.

Anyone any thoughts on the idea...havent given up yet...but I'm close!

pete

[onelastgoodbye]

OK, so I was checking out this router fingerboard radiusing jig idea...

ROUTER RADIUSING JIG

Can anyone see a way of making some kind of jig that could route the steps on a wooden fingerboard without getting all CNC on me?

It maybe that a thin glass coating that could be recoated or maintained in some way, or a routable material other than wood that's wear resistant may be the way to go rather than molding as a concept.

Anyone any thoughts on the idea...havent given up yet...but I'm close!

pete

←

I actually think the tiling idea might work best. Say you route a complete fingerbord with the jig, then cut it up and tile it, making sure the tops are aligned and spaced, glue it, then you shave the bottom of your glued assembly flat. It's quite a task getting it all lined up, but it might be less work than trying to get all the individual steps routed correctly (setting the router for correct fret spacing) if you tried to do it in one go. Maybe if you had a counter-form or a negative mold where you could fix the tiles, the gluing process would become easier.

[tirapop]

Cool radiusing jig... totally unsuitable for routing stepped fretboards. Too imprecise, too many setups (22-24).

Use the radiusing jig to make a fretboard blank, cut it into tiles, use the glued up tiles as a master for a duplicating router. It probably isn't precise enough, but, it will get you most of the way there.

"Thin glass coating"? They must be making breakthroughs in vitreous technology in your hemisphere. On our side of the equator, glass still has to be pretty hot before you can form it, which isn't good for wood substrates.

If you're thinking glass or glass/epoxy, I think you're stuck with molds. With "coatings" or overlays I don't think you'll be able to hold the tolerances on thickness you'll require for buzz free frets. You could grind the glass surface, but, that would be time consuming and expensive... just the opposite of why you want stepped frets.

If you go with the metal (glass/ceramic?) plates at the end of the steps, you might have a short term solution. Build the master with tiles, indexed to the fret radius surface. Use the duplicator router to recreate the surface, ensuring that each "fret" has the same height from the back of the fretboard. Cut slots at the same depth at the end of each step. Bond in precision laser cut fret plates into each slot. The trick is to work out how to do this without the bondline pushing the plates out of tolerance. Bond only to the slot face, not the bottom of the slot, and put in a groove to hold adhesive while the plate bottoms out on the slot face. Yes, it's probably a wash in time and effort compared to conventional fretting, but, this is the best I can come up with.

[psw]

Thank's...I meant smoe kind of glass/epoxy coating...or something...but I take your point.

I did nut out a jig plan though if one were to want to route steps.

Basically you have two rals parrallel to the work piece. You then have a router base with curved radiusing rails and with the router mounted at the angle of the steps. You then have an indexing rail that fits into grooves in the rai at the correct fret intervals. You then just work your way along the piece cutting and radiusing from side to side.

Anyway, I think it could be done reasonably easily but it's the surface wear that's going to be the problem...there may not be a reasonable solution. Although the glass/epoxy mix stats held up pretty well in comparison, I'd be a little concerned that the stuff would simply chip off on the edges of the steps. It would leave open the option of resurfacing the board perhaps!

thanks for considering the idea...still haven't got round to testing any materials yet

pete

[tirapop]

The problem is going to be trimming the end of the step. It isn't parallel or perpendicular to the the curve surface. So, you'd have to have a collet on the router and a curved template, in 2 dimensions! It would be on the fretboard radius curve and it would have a curved profile.

Come to think of it, your indexing scheme has a problem. If each step has the same angle, the depth of the step varies from fret to fret. If you index off of the previous fret, you have to change the depth each time. If you index from the fret you want to cut, you have to make incremental length stops for each fret position.

[psw]

You're right...but perhaps it's overcome-able.

The indexing rail could slide in varying depth slots which would change the angle of the frets perhaps. hmmm...another set of problems.

Or maybe, you need to use a cutter big enough to cut the widest step in one pass.

Also...if each step has a different step depth...does it really matter as long as the step heights and radius is consistant.

Anyway...everything means little if there's no coating...or perhaps the moulding solution would be better.

I'm still not sure that ultimately conventional frets may well win out hands down.

pete