Fret Wear from a Mechanical Engineer's View

[Tom Coletti]

As a musician, I see the mandolin as a voice and means of expression.

As a painter and model builder, I see it as a piece of sculpted art.

But as an engineer, I see it as a machine, something that requires routine inspection, maintenance, and the occasional overhaul to function at its best for the longest possible working life.

From my experience building scale replicas of locomotives, friction surfaces, whenever unavoidable, are designed in a way to make the parts that wear down the fastest be the most easily replaceable, with more permanent, complex, expensive, or difficult-to-make components designed to maintain their shape and integrity where they meet other components. Full-sized locomotives have had drive rods last over a hundred years with minimal work because of this.

This was done by forging steel drive rods and steel crank pins with a brass journal bearing in between, so that the simple bearings of a softer metal will wear down and the rods and cranks remain intact, then the bearings are replaced at regular intervals.

Ideally, I'd like to see the frets of an instrument perform the same as the rods and the strings as the bearing, so that the frets wouldn't wear down nearly as much and whatever wear-and-tear is afflicted on the strings would be negated by regular string changing.

However I tend to see the opposite on the A and E courses. These are plain-wound steel, which is harder than the nickel fret material on most instruments, or equally-hard to the steel frets that some builders are using now. Either way it causes uneven fret wear that requires dressing and eventually a re-fret job.

I can see two ways of reducing fret wear based on the relative hardness of metals: either using top strings of a softer material or using frets of a harder material, each with drawbacks. Nickel top strings on steel frets would theoretically reduce fret wear but I'm not sure if they're available in any string sets, only as singles for electric guitar strings, and even then I'm not sure if they're pure nickel or just nickel-plated steel or what effect that would have on tone.

The other would be using a metal that is harder than steel for frets, but that would affect the workability, as it would then be a harder material than a lot of shop tools. So in those regards, I have a feeling we won't find a magical way out of fret dressing and pulling any time soon unless we were all blessed with chromium-steel frets and tungsten carbide tools... but we can dream, right?

[Ivan Kelsall]

One way out of the problem (partially),is to use fret materials that tends to 'work harden',as in the case of EVO Gold frets,which is an alloy of copper,a material well know for it's WH properties. However - even that won't last for ever,but it goes a long way to avoid re-frets every couple of years,
Ivan

[kjbllc]

so what is the best option fro longer fret wear under the stated conditions? thanks

[Marty Jacobson]

How about solid carbide frets with an oval cross-section bedded in brass recesses and adjusted with jack screws, like jointer knives. :-) They'd be about $8 apiece but would last forever and could be adjustable in height and angle.

[sunburst]

Mandolins (and other stringed instruments) are under constant, though somewhat variable, tension/compression/push/pull. As a result, instruments are not infinitely stable. Most are made of wood which is subject to movement resulting from moisture content, subject to plastic deformation, and in general... things move. When things move, frets can be less than optimally level and need to be adjusted. In order for an instrument to be easy to play and to perform near it's optimal level, frets need to be pretty close to optimally level and adjusted. Using a very hard material would make standard fret work impractical for the luthier using standard tools. I do use diamond sharpening "stones" to level fret tops, but that is only practical for final leveling when things are already pretty close, and diamond re-crowning files are available, but we're still talking about a nasty difficult job leveling.

Re-frets are straight forward, standard operations for luthiers. Using harder material (like SS) makes the job more difficult, as does unusual methods of attaching frets (like Fender frets pressed in from the side, glued and epoxied frets where the slots must be meticulously cleaned for re-frets, etc.).

So anyway, from a mechanical engineer's view things seem to look a little different from the way the look to a luthier.
A stringed instrument is an imperfect system that was not designed as it is but rather more-or-less evolved from earlier instruments, and frets went from pieces of gut tied around necks to bars of metal to modern "T" frets. Bar frets are probably the most durable if they are made from hard material (and they can be much more easily than "T" frets) but they are far more difficult to adjust.

[Jess L.]

As an aside, frets last a lot longer when the player doesn't mash the strings down harder than is actually necessary.

[pops1]

I prefer to replace worn frets, if there only a few, as opposed to leveling them. It goes a long way toward longer life of the frets where the wear is minimal. Another thing I will do instead of leveling them is if there is no buzzing going on I will simply crown the dented frets until the dent is minimal and in the center of the fret. This keeps the string in the center where it is supposed to be without losing any unnecessary material off the frets. Again extending the life of the frets considerably.

[Tom Coletti]

So anyway, from a mechanical engineer's view things seem to look a little different from the way the look to a luthier.

Which is precisely why I appreciate the feedback; it has been extremely helpful in understanding how the approach to luthierie differs from the conventions of manufacture that I am more familiar with, and it'll be invaluable in guiding what could potentially be my first instrument build one day.

[Mandoplumb]

Pops I dress mine as needed also but there comes a time that frets do need leveling and even replaced. Keeping them dressed just postpones the problem. The strings are wearing groves in the fret even if you just remove the metal they have bradded. I get about 10 years out of frets before replacement usually a couple levelings in that time.

[sblock]

The OP makes a technical mistake, I think, by considering this purely as a mechanical problem. It's not merely that: it's a musical problem, as well. The choice of materials that comprise the unwound strings (a specific alloy of steel) is not made solely on the basis of hardness and durability, but also for its sonic properties. Deliberately selecting a less durable (i.e., softer) material for strings, just so that these will serve as "sacrificial" surfaces and wear out before frets, effectively neglects the musical reasons for choosing steel. Steel strings happen to give us the mandolin sound we want. If you wanted your frets to least nearly forever, you could easily switch to playing with nylon strings. But if you did that, your mandolin would sound vastly different, and I doubt that you'd prefer it!

Which brings me to my point. There are certainly tradeoffs to be made, but the OP is a bit naive to think that these have not already been considered from an engineering perspective by a great many experts over the years! Among the developments introduced in the last few decades have been newer formulations of steel for strings, and longer-lasting alloys for frets, such as EVO-gold (which work-harden) and stainless steel (which are harder ab initio). These types of frets last longer, but they are harder to work with during installation, re-installation, or periodic leveling. Many luthiers charge extra to work with stainless steel frets, for example. And some also charge more for EVO, as well. But if you are very hard on your frets and/or play a lot, they may be a worthwhile investment.

So NO: nickel strings would not sound the same. This metal has different internal damping than steel. And so, in all likelihood, would almost any other 'sacrificial' material. Luthiers have converged on steel for good musical reasons. And NO: tungsten-carbide frets would be nearly impossible to work with (cut, trim, file, round, level), and require entirely different tools.

That is not to say that there is no room for improvement! However, most of the simple solutions you suggested won't cut it. New generations of materials may eventually come along that will, however. For example, just look at how space-age plastics (particularly polyimides and polyetherimides, used in BlueChip and Ultem picks, respectively) have replaced the use of shells from endangered species, with --arguably -- sound that is as good or better. And these special plastic materials wear better, as well, lasting much, much longer!!

[HoGo]

I think the modern SS or EVO frets shifted the problem to where the fingerboard surface wil wear (or like John pointed out deform or move) excessively before frets get worn... Typically luthier would "plane" fingerboard during refret giving it nice profile, strainghtness and smooth surface again.
I've used SS frets on several instruments and they are close to indestructible.

[pops1]

Pops I dress mine as needed also but there comes a time that frets do need leveling and even replaced. Keeping them dressed just postpones the problem. The strings are wearing groves in the fret even if you just remove the metal they have bradded. I get about 10 years out of frets before replacement usually a couple levelings in that time.

Yea, I do this a few times before leveling. I have leveled my mandolin frets twice now, but this keeps it playing better in between. It will be time to refret it again soon and I am thinking EVO this time. If I only played in first position I would replace only those and do a minimal level to match them to the old ones, but I play up the neck so that doesn't work for me. There are a lot of folks that don't go up the neck so I prefer to leave those if I can and replace the first 5-7 depending on what is worn.

[Jeff Mando]

Many great points, made by all! From a repairman's point of view, the consumer/player's misunderstanding of fret wear is what keeps repairmen in business, IMHO, of course. Bread and butter, so to speak! Let me explain. Sure, we would like to invent a set of car tires that would last forever and never show wear -- well, compared to 50 years ago, we have. Who ever heard of tires lasting 50-75,000 miles, back then? I remember as a kid, taking a 250 mile trip to Kentucky to visit Grandmother and we always had to change at least one blowout, sometimes two. Tires have improved by leaps and bounds in the last 50 years.

OK, frets are a little different. Like cars, it depends on the driver. And sure, a buzz is a buzz, and needs to be dealt with. BUT, there is plenty of great music being played on worn frets everyday, as we speak -- it is just a fact of life. A professional using the same instrument MAY need to refret 3 or 4 times in a 20 year career if he plays the same instrument every night, which not many do these days. In between refretting, the frets can be dressed, of course, to improve clarity and useful life. I think MANY amateurs and hobbyists overthink the fretwear thing and base the need for a refret on looks rather than sound, IMHO. Like I say, a good thing for repairman, but not always necessary. From what I have read on this website, many hobbyists are having their instruments refretted more than professionals do, and certainly more than necessary, IMHO.

[colorado_al]

I'm a fan of EVO frets.
That being said, having a spare mandolin (or 2 or 3) to play when your main instrument is in the shop for fret work, is part of the fun. Also, using different instruments from time to time helps forestall having an instrument in the shop too frequently.
I usually play until there is a buzz and then get the work done.

[Tom Coletti]

Again, more good feedback to read here.

sblock, you are correct in nickel strings having non-ideal tonal qualities, I should've clarified that as one of the major drawbacks. And since an old adage of the cafe is "search the forums" to see if similar discussions have taken place before starting new ones, I didn't see any fret wear threads that approached the topic from the angle I chose, hence why I proposed the different perspective to see what new results would come back on this thread.

Jeff Mando's analogy also brings up some self-awareness to the use of analogies, and in doing so would lead me to revise my initial comparison to the rods and bearings of a locomotive. Given the responses here, it seems the convention is to think of the neck and fretboard as the more permanent part to which wear and tear is to be avoided, while the frets function like the bearings as small pieces that are more readily replaced through normal use, and that distinction helps to recontextualize the instrument.

And HoGo, on the topic of fretboard wear, the jumbo frets on my Breedlove actually make it so that a fretted string doesn't make contact with the ebony between frets at all, so I wonder if large frets were specifically chosen not just for feel or extra room to level, but for the purpose of keeping strings off of the fretboard to reduce wear on the ebony.

[Phil Goodson]

....And HoGo, on the topic of fretboard wear, the jumbo frets on my Breedlove actually make it so that a fretted string doesn't make contact with the ebony between frets at all, so I wonder if large frets were specifically chosen not just for feel or extra room to level, but for the purpose of keeping strings off of the fretboard to reduce wear on the ebony.

I doubt that you will find that any strings hit the fingerboard, regardless of fret height. The wear comes from fingernails.

[sunburst]

Strings nearly never contact the fingerboard on fretted instruments. People with fingernails that are too long can cause serious fingerboard wear, but the wear often comes just from fingertips themselves.

[CarlM]

Even from a mechanical engineers point of view there are several misunderstandings. Sleeve bearings, like a locomotive, are always of a softer material, like babbitt or bronze, than the crank. If they are equal hardness, the bearing and the crank will wear massively. The ideal is a self lubricating material like oillite bronze but embedded oil or graphite is probably not going to help the sound. Ball and roller bearings have had immense amounts of research and development in materials and design, going back 120 years, to solve that small contact surface wear problem, and they still wear out eventually.

Carbide on steel gets away from the equal hardness problem, but speaking from having worked extensively with carbide punches and dies there are several problems with that idea. The first being that if you only support it in a couple of places, like with an adjuster screw, a small piece like a fret will break. It is as brittle as glass. The second is that in the volumes that frets are used the cost will probably be closer to fifty or a hundred dollars per fret than eight. Metal cutting inserts are produced in huge volumes to get their cost down. And they are larger cross section making them easier and less costly to produce.

As has been mentioned, EVO or stainless are good solutions but more difficult for the guy doing the work. Even with stainless, the fret material is still softer than the steel of the string.

[Tom Wright]

Considering the wear and bearing issue, can we note that axles and engine parts use lubrication?

In the case of frets, it feels to me that EVO offers less friction, and less wear occurs as a result. It certainly feels slippery, how the strings can slide sideways for bending notes. The alloy includes titanium, for what that's worth. My luthiers have not complained about difficulty in working with it, and one commented he was impressed with the accuracy of manufacture. I have it on all my 10-string mandos. I killed the low frets in a few months on my first Buchanan. The second still has excellent original frets, in EVO 0.80.

EVO is the solution for steel-stringed instruments.

[Ivan Kelsall]

From Tom Wright - "...The alloy includes titanium,..". Tom - Titanium is another metal well know (notoriously so) for it's work hardening properties. I didn't know that EVO Gold fret wire had both Copper & Titanium in it - it should almost last for ever !!,
Ivan

[Paul Busman]

How about solid carbide frets with an oval cross-section bedded in brass recesses and adjusted with jack screws, like jointer knives. :-) They'd be about $8 apiece but would last forever and could be adjustable in height and angle.

Great idea! I play mainly Irish trad, so I'd only need about 6 of them

[multidon]

This had been a very interesting discussion. I was especially intrigued by CarlM’s statement that even with stainless steel, the steel of the string is harder than the fret material. This spurred me on to do some online research.

Steel strings are made from high carbon steel, of the type known as “music wire”. The alloy used is, depending on the source, known as A227 or A228. Hardness can vary quite a bit, I assume it depends greatly on details of the manufacturing process. But range of hardness in terms of Rockwell C seems to be between 41-60, which is wide indeed.

Fret material hardness figures are difficult to come by, but Luthiers Merchantile does give hardness figures on the Vickers scale as follows: Nickel silver, 200; EVO, 250; Stainless, 300. Let me point out at this point that there are numerous alloys which qualify as “stainless steel”. As a term it is largely meaningless unless you know the specific alloy, because the properties of the alloys vary so much. About the only thing they share is corrosion resistance. I don’t know which specific alloy is used for stainless steel frets but accepted the hardness figures given by LMI as accurate. Problem is, now we have differing units, Vickers and Rockwell C. To make a comparison, conversion is needed. Let us assume the softest hardness specification given for high carbon music wire, 41 Rockwell C. This converts to 390 Vickers!

So, now it is easy to see that steel strings with no windings must inevitably wear any fret material. Nickel silver? No contest, 390 vs 200. EVO, 250 vs 390, better but still no contest. Stainless, closest but at 300 vs 390, wear would be slower but still inevitable, all other things being equal.

But are all other things equal? I don’t know. People talk about ‘work hardening” properties. I am not a metallurgist, so I just don’t know to what extent these materials would increase in hardness over time. But CarlM’s statement seems to be correct as far as it goes.