Official Luthiers Forum!

I'm just starting up my business, I'm disabled and need something to do. I aprentesed with a luthier in the late 70's early 80's. I was a mechanist moving up to cnc mill programer and manufacturing engineer for most of my life I still did tune ups and small repairs on guitars for friends.
I was taught to do fret jobs leaving a .015 to .025 inch flat on top of the frets. The instruments played well and intonation was fine so why the change to fully rounded frets.

Easy. Because intonation is so much better on fully rounded frets.

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"Act your age, not your shoe size" - Prince

And better still on pyramid frets.

Hi Scott and welcome to the OLF!

Fully rounded is how the fret wire comes off the machine and what we purchase and what we see when no one has gone to the effort to do a precision leveling. Some f*ctories these days install the wire as is and don't even do a leveling and recrowning so we see perfectly rounded frets.

IME leveling is a must especially if low action may be desired and I wish that I had a dollar for everyone that has asked me for low action so it's a good idea to set-up instruments so that they can be set fairly low if this is what your customer desires.

Your .015" to .025" flat spot if the flat results from a precision leveling is fine and darn near perfect in my view. When we level frets and then recrown we create a line (what you called a flat spot) that can be seen on the top of the frets. The line is the level set if you will resulting from the precision leveling effort and needs to be preserved or if the line disappears we have taken that fret too low. A low fret in respect to it's brothers and sisters can most certainly be problematic and more so with lower action.

So we want to preserve the line or flat which is important to preserving the level set that we created but we also want to recrown and round the fret crown for reasons of intonation as mentioned. Both are very important.

As such in our efforts to make that line pretty fine while crowning it at times gets broken a bit which is usually OK too. But if I had to choose preserving the line resulting from a precision leveling is every bit as important as a gentle, rounded fret crown.

I've been making my lines pretty fine and getting some breaks at times and very recently and as a result of a discussion with experts who I respect in the trade I've decided to focus more on preserving an unbroken line over getting the line hair thin.

I think that what you were taught is spot on and even a .025" line is not going to be problematic for intonation. There is a formula that IIRC says something such as .007" of variance equals one cent of variance in the resulting note. Of course there are other factors and this is an estimate. If we divide your worst case line the .025" line by two to see how this might impact intonation we have .0125 which per the formula is about 1 1/2 cents of variation. This is not perceivable by most unless of course they are super human.... Your best case flat spot at .015" is even better at just over one cent.

To be clear what you call a flat I call the line resulting from leveling.

Also related is how accurate the fret slotting is/was, scale length, and a few more nits that I can think of too.

I think that what you were taught is excellent advice and will serve you and your customers very well.

Again welcome aboard!

The guy I aprentessed with had perfect pitch, and claimed he could hear notes in a chord being a few cents off. He was happy with the intonation, and we never had a customer complain. I understand that technically it should be right but a fretted instrument is a compromise and the stretching of the string pressing it to the fingerboard would through off the pitch as much or more than a .020 inch flat. I just need a good reason to spend $40 to $90 for a tool that I'd never had use for. If I have enough people say it's worth it I'll start doing it that way.

That's right not only the pressing of the string is a factor but fret height is as well, how well the nut slots are cut, how low is a factor for the first fret, and the "touch" of the individual player is also a factor. I know players who never touch the fret board at all..... and in doing so minimize many of these factors.

Can't tell you why you specifically should purchase anything but for me the modern crowning files, the diamond ones most certainly are justifiable and make my life easier and help me avoid the opportunity costs of one job over another because I can complete the work faster. A diamond file works in both directions, that's half the effort and time to crown a fret over a conventional fret file. Three corner files work great too and have for decades.

I'm a big advocate of folks doing what ever they wish and no one knows your specific situation better than you. So I can't give you a reason that might work for you but I can tell you that for me and our shop we all appreciate and benefit from the modern diamond crowning files. In fact we just spent around $300 on some new files and likely have over 15 of them in our shop at present.

In our market our clients tend to be pretty educated in various aspects of what good repair work is. We also have Elderly Instruments in our general neighborhood as well. As such we have to do the best possible work at all times. I'll add that it's a sincere and shared desire for us to always do top-shelf work so we can't afford on many levels to cut corners with anything that might impact the faith and trust that our clients place in us.

Some folks can do fine with a three corner, inexpensive, effective, a staple of the industry for a very long time now. Others like conventional fret crowning files although I find that they can chatter and scratch more than I like.

Modern diamond files if that is what you are looking at are most certainly not required. If they are expensive or not is subjective to the volume of work that one does and their individual situation. I will say what I frequently say that some of these speciality tools from say Stew-Mac are really, believe it or not, quite the bargain. The world-wide, total life cycle market for some of these things may only be a couple hundred units. You are a machinist so you know that small batch production is far more expensive than large runs with the automation available today. Stew-Mac tries and succeeds in my view in serving both pros who use and abuse these tools every single day and hobbyists who may not be able to justify an $80 fret file for a single kit guitar.

I don't think looking for what others would advise you to do is the answer for you. Instead my suggestion is to try some of these tools, visit local Luthiers and see if they will let you check out their files on some sample frets and see what you think. Might be just the thing for you to decide what you want to do.

I think a flat place on top a fret increases friction (especially if it is not buffed to a high sheen) which makes playing and string bending more work. Many times when I do a fret dress for someone with a Gibson style factory fret level, and I hand them back the crowned, buffed frets, they test it out and tell me that it plays much easier. Sorry, but I think a flat fret is just a short cut.

Great fret work is "the way" to successful guitar repair work.
Nothing else will make your customers as happy.

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Yep. There is that formula. Where does it apply? (12th fret only.) Flat top frets? Not an intonation issue. A workmanship issue. When I see flat frets (polished or not), I think "poor workmanship".

There is absolutely nothing worse than flat top frets, and it gets worse as they wider. If there is any doubt try it on jumbo width

Steve

I didn't get the impression that Scott, the OP was actually talking about what I would consider a flat topped fret. He gave specifics, .015" to .025" saying this is what he was taught.

Now I could be wrong here in my read of the question and post but a .015" to .025" "line" or flat if you will resulting from the leveling process is fine. He's not talking about the Gibson fretless wonders with huge flats and we never got to polishing, yet, and the benefits of the glass like feel of highly polished frets.

The "line" resulting from leveling is the level set of the entire fret plane if done the way we do it and many Luthiers do this. As such it needs to be preserved, the line that is and of course it needs to be pretty thin too and Scott's specs that he was taught are pretty thin and not what I would consider a true flat topped fret. Remember too in the sanding and polishing activities depending on how one goes about it this very small flat or line get's it's corners broken which can refine the crown even further or, if not done well can widen the flat as well.

Maybe I'm misinterpreting the question here but my read is not an advocacy of flat topped frets but more a question about what tools the OP could justify with a standard of workmanship and specs provided that he subscribes to which, by the way, is a pretty fine line IME.

Might be semantics here that's throwing me or perhaps others off too but I still don't see anyone advocating flat topped frets.

More specifically when we level we create a flat where the beam contacts the fret crowns. Next we recrown with what ever tool floats your boat. In the recrowning process where the beam kissed the fret top is refined making it a very thin contact area at the peak of the fret crown. Look at it closely enough and it's flat but.... when this flat is only .015 - .0125" it's a pretty fine line. Eliminating this line or contact area in pursuit of a perfectly crowned fret with an even finer peak results if the visible line gets broken in taking the fret height below the level set achieved with the beams. This is not desirable and can leave you with frets of differing heights which gets more problematic as the action is lowered.

It has to be a balance of sorts striving for a very fine line that preserves the level set but also refining the fret crowns so that this line or flat if you will is as thin as possible without breaking the line or flat. Scott's specs that he was taught seem very good to me.

But like it or not guys by some measure if the level set is preserved there will be very minor flats if only a thou or two wide. Chasing these flats in an effort to have a perfect crown with the thinnest possible contact area invariably can lead to reducing the height of a fret and ruining the level set achieved with leveling, not a good thing...

So my read of the question is that the OP was taught and can achieve line widths of .015 - .025" on the fret crowns with the tools that he has now AND the Luthier that taught him never received any complaints. Scott's worst case flat/line is the width of a Fender medium pick.... I think that's fine. Finer may be better but not if approaching this breaks or eliminates the line in sections also making that fret lower than the rest in the broken line areas.

As a builder you have to learn that the neck and frets are the part of the guitar that makes the body work. Fret work , especially fret plane is critical. The position of the point on the fret to the saddle becomes more critical as you go up the neck. One thing is that there is no one perfect way for every player so learn you clientele .
A finger picker with lower action will usually prefer a set up different from a flat picker. The contact point is critical and good finish work makes it look better. Flat spots can be a point for buzzing. I prefer a more school bus shape. It is all about feel.
Learning and understanding the variables on the neck and fret lane will allow you to make the best adjustments for intonation. Also what works well on electrics may not translate to acoustics and vice versa.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

You guys are often working on new builds where the frets are still full height.

In the repair world it's frequently the case that we have to remove a LOT of fret height from some frets that are too proud of the desired fret plane so that we can make contact with all of the frets. Causation can be that the instrument was fretted with the board off the neck providing no opportunity to level the board on the neck with the neck on the guitar prior to installing the frets.

In any event when we have to take some frets way down, and this is pretty common by the way with a few examples being the ski ramp on the extension of Fender bolt-on style necks or simply instruments where there has been a lot of movement over time of the neck and board. When this is the case the fret sides can be much more vertical than the gentle crowns of new, untouched wire.

A school bus shaped fret can have edges where the vertical fret sides intersect the crown imparted by the files. With three corner files we can file away this edge.

The modern crowning files be they diamond of conventional will impart a school bus roof shape to the frets when having to take fret height down considerably if the files are not rocked back and forth during use. This is a problem that I had early on and had to address because if you don't and leave the sharp edge where the fret crown intersects the more vertical sides of the fret this edge can be sharp and felt with the fingers when moving up and down the neck.

Rocking the files is an acquired skill, that is rocking them and not slipping off and scratching the hell out of the fret in the process. So some folks don't rock the files and the files then impart a school bus roof shape to the fret crowns. No problem with this if you follow-up with say a three corner file and five or so swipes on this intersection edge and Bob's your uncle. A properly safed three corner won't mar the board either.

I'm concerned about the sharp edges left with modern crowning files and again it's more of a problem for repair folks because we have to take frets down further than new builders should ever need too if using best practices. So I just follow-up after crowning with the three corner and it only takes 10 seconds or less to do a fret and eliminates these edges left from not rocking the crowning files.

In the repair world we also have to recrown frets that are at times too low for a modern crowning file to even touch the fret without bottoming out on the board.... Granted this is a very low fret and a refret would be advisable but not everyone's budget permits a refret so we work with what we have. In these instances a good old three corner may be the only choice.

For builders with a new build if you level the board on the neck with the neck on the guitar your crowning efforts should be very minimal with the goal being simply making contact with all frets in all locations with the leveling beams. It's been said by someone who used to post here that no leveling at all is required, not true, you still need to do the leveling process to even know if no leveling is required and see where the beam hits the frets.

Repair is a very different animal from building in that you guys work with new stuff in terms of fret height, etc. In my M - F world I may have to recrown a fret that is only .017" high..... and .080" wide.... To add insult to injury it's likely that there will be many more than one fret like this too.... Oh joy....