Official Luthiers Forum!

Hello,

I have a Jackson Dinky c. 2007-2010 model. I bought radius gauges from Stewmac but none seem to fit the fingerboard snug (I've tried it on different frets down the fret board just to see if it was a compound radius but I don't believe it is). Light shines through the bottom of the gauge on every different size (14, 15, 16 and 20"). Is it possible I'm using such a simple tool wrong?

I'm new here and also an amateur hobbyist, would appreciate any help I can get!

What do you mean by "the bottom" ? At the center line of the fretboard as opposed to the edges? Is the gap the same at every location as opposed to being more or less at the higher frets?

If the gap is at the center line, the radius is greater (meaning flatter) than the gauges.

If the gap is the same at every location, the radius of the fingerboard is constant, if it changes, it's compound.

Hope this helps.

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

Sorry by bottom I meant the edge of the corresponding radius gauge (I used the wrong term when I said "bottom"). I doubled checked and all the gaps are the same so that answers my question about compound vs constant! So what I'm concluding is that the radius of my fretboard is greater than 20"? I didn't think they made them that flat...


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Sure they do and one builder who had a book written about him and Clapton builds or has built with no radius. Classical guitars as well can be pretty flat.

Tell me please you purchased radius gauges from Stew-Mac wanting to know what the radius was on your ax. What problem are you attempting to solve?

We've had several through for refret in the past six months, and all were 12" to 16" compounded radius fretboards. It's possible the neck is custom or one of the special editions that comes with a constant radius 16" or oddball compounding scheme.

As for using the tool correctly, I've seen several instruments where the fretboard is radiused to one value and the fret tops themselves another, particularly with the higher jumbo fret wire popular on these guitars, so worth measuring both to see what is going on. Also - fret end and fretboard edge treatments can make it tougher to accurately determine the fretboard or fret radius. One of the boys in shop pointed out that it's the area between the two E strings that matters, so a rolled fretboard edge or long across-the board edge bevel on the fret can make one radius look like something larger or small.

I will echo Mr. Breakstone's concerns - is this curiosity on your part, or is this an attempt to diagnose a problem? If the later, you might discuss the issue and let the repair people here have a go at helping out.

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A constellation only takes shape when one maps the whole.
- Beth Brower

I have seen, and made, classical fret boards with a 1 meter radius which is flatter than 20". I made press cauls for them out of flat Stew Mac cauls.
At least there is one caul I spent time making that isn't covered by the,"ultimate fret caul set"!

Hello all, thank you so much for the help this is a really great forum! To answer a few questions I am trying to find out the radius so I can buy the correct radius sanding block to do a great redress job


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*fret (not great)


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You can make your own gauge with a pencil, string and paper and no need to purchase radius gauges from anyone. You also do not need a radiused block to level frets and instead a "leveling beam" does great.

Check out Technofret on eBay for leveling beams.

I just checked out the Technofret, I see that it spans the length of the entire fretboard but does it allow u to sand the entire width of the fret at once (from high E to low E) I can't tell from the pictures


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u don't need to span the width of the frets to level the frets, that's a myth or simply another way that it can be done but it does not have to be done that way. Instead when using leveling beams that are the narrow variety you work them simulating the direction of the string path.

Again, I'll suggest that Mr. Breakstone has cut to the heart of the matter - the string path is the important thing here, which is why frets are leveled along those string lies. Moving a narrow, flat beam between string lies in a controlled manner will naturally result in a radius for each fret that is close to the ideal and a smooth variation in fret radius between the nut radius and the end-of-fretboard radius (for the Jackson, probably 12" to 16").

On keeping the leveling block in contact with the full surface of each fret...it cannot be done on a compound radius board. Both block and board are sections of a cone; move them out of registration - by, say the act of moving one against the other along their length - and they move out of registration. The 14" radius desired at the mid-point of the board cannot be shaped by alternating between 13-1/2" and 14-1/2", as might be the case when moving the block along the face of the board.

As to constant-radius boards, yes - a block will cut a constant radius - but that fretboard's string lies will not be level, and the greater the angular divergence of the string lie from the board's centerline, the greater the curvature in the string lie and the greater the relief/higher the action necessary to accommodate string movement. In short - a constant radius fretboard/fret plane is a cylindrical surface, while a guitar's string plane is conical.

_________________
A constellation only takes shape when one maps the whole.
- Beth Brower

Of the dozen or so I've worked on or played, they've all been radiused, and the ones I've refretted have all been 16".

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Mountain Song Guitars www.mountainsongguitars.com

Hesh, I think I understand what you mean, but I am fairly new to fret redressing and the only reason I asked if it covered the width of the fret is because I would be nervous that I may accidentally shave off too much on one side, unknowingly....is this a common problem?

Woodie, so will using a Technofret create the desire compound radius that I need? Also, you said frets are leveled along string lies and then you say between fret lies...I'm assuming that I need to level the entire fret, obviously?

This a great piece of advice -- and actually I'd call it a warning, I suspect many fretted finger boards have been screwed up using an abrasive covered radius block, removing way too much material from the outer edges of the frets while sometimes completely missing the center. A flat beam is the way to go.

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Ken Cierp

http://www.kennethmichaelguitars.com/

Not to be a spoiler, but here are some words of warning: Before you attempt to level frets on a guitar you cherish, buy a cheap used POS and practice on it first. Before you touch a tool, learn about (and understand) the geometry of fingerboards, and how truss rods work, but do so with disbelief and take your findings with a grain of salt, as there is much myth, mysticism and snake oil in the guitar world! Take consultation from physicists, mathematicians and seasoned luthiers, over guitar players.

The tool does not make the job!!! Just because there are all of these wonderful tools to do fret jobs with, does in no way guarantee it will turn out anywhere near acceptable. There is a high level of skill involved, that can not be acquired from books, YouTube flicks or any advice. Even known methods do not work well without paying close attention to the neck at hand, and observing how it reacts to truss rod adjustments and string tension changes. I have had the pleasure of redoing many a fretboard that were not done well, even by professionals in business for years, because they relied on some jig or another, but fail to understand that the neck will come off the jig, may be bolted on, be strung up and the truss rod adjusted, all changing the relief to where it really wants to go, and although you may end up with a good fret job, it may still be far from a great one. Just because a truss rod can adjust the bow in the neck, does not guaranty it will do it in just the right way.

Not to scare you, but to get that super low, buzz free action many players want, we are talking 100,000ths of an inch accuracy. A great action has less relief under the high strings, and more under the low ones. A fingerboard with close to physically possible lowest action, is therefore not truly conical nor radial. Frets should not follow a radius (a radius is based on a circle), but rather a curve. A so called "compound radius" fingerboard is an off axis section of a hyperboloid, and unless your radius gage can be adjusted by the thousandth it is just for general reference, and mostly useless.

"Compound radius" is not even a real term, no where to be found in geometry, and is used only in guitar speak. Someone used it in error, and somehow it spread and no one called it for the error it is and corrected it, just like "tonewood" is not a real word. Hell, it is also not true that a "compound radius" prevents strings from touching the next fret within bends, quite the opposite, geometry dictates that if the fingerboard radius is flatter on the fret past the one you are bending on, then the string is higher off of the next fret in the bend than it would be when played normally (not being bent) because of the angle of the string to the bridge. Add to that the increase in string tension within a bend, narrows down the helix of the strings vibration. For the same reason, it is also false that a "compound radius" can have a lower action than an even radius or flat fingerboard, again, the opposite is true. The real reason for the so called compound radius is ergonomic: as the frets get closer together, the string spread increases to allow for more accurate playing, and having less radius going up the neck compensates for the hand positioning to play the wider string spread, making it more comfortable to play up high. The difference is not really that noticeable though, unless you have short sausage fingers!

I consider myself lucky to have had to learn to do what machines do by hand first (accurately), before I was allowed to use the machines, during my apprenticeship some 36 years ago, and it helped me learn fret work better and faster, but I was still out of my league when I attempted my first fret job, and none of the books on the subject explained how to read a neck, how and where to adjust pressure during sanding to draw in relief... In the end it is sculpting, and is one of those things that you must develop a feeling for, and will not get right without paying very close attention to detail.

Guitar players are spoiled when it comes to action anyhow, and if you think 1/8" over the 12th fret is too high, try a sitar on for size!

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If what you see is what you get, then Stevie Wonder ain't got nothin'!

I'm glad to see someone else is working to the same standards that we are - the nearest 5/millionths of an inch. By way of comparison, a piece of copier paper is about .0035", or 700 times thicker than the standard we routinely achieve.

Measurement costs go up a bit, what with the laser interferometers and optical benches necessary to work at micron scales, but the results speak for themselves. We ended up having to spend a little money to build the floating, vibration isolated foundation for the optical bench to allow us to work at this level of accuracy, and the .1 deg/sec temperature and .01%/sec RH control system was a little pricey (even minor changes in temperature and humidity cause far greater movement of wood and metal than our desired accuracy), but our customers agree that it makes a difference.

The boss is now exploring how to get to angstrom-level accuracies (1/1000 of a micron, or 3.94e-9") for setup work, but having the player in the same room as the instrument - much less play it - results in unacceptable changes to the setup. Once we have that licked, I think we'll see some real customer interest!

_________________
A constellation only takes shape when one maps the whole.
- Beth Brower

I have the Stew Mac radius gauge tools as well and they hardly ever get used and when they do I always have a difficult time getting it right. Just find the one that is closest fit and call it a day.

Well, at some point you have to say "good enough"! As most of your customers have no way of recreating such tight tolerances at home, will change strings sooner or later, knock the thing around a bit, or play it long enough in one spot for the temperature difference on the neck to throw it off by 1/100"... If they report to notice a difference that minuscule, it is only perceived in mind and really due to the placebo effect, just as they can tell a great improvement in sound from the set of two "matched 1% tolerance" capacitors they forked over $100 for (.02 cents to make), some even with the tone control all the way up, on guitars with unmatched pickups and potentiometers all under + -20%! Don't forget the Gibson guitar polish that does not soak into the wood of your guitar, ruining the sound like all other polishes do, and therefore must have since guitar polish was first sold. Hell, I had to get an old laundry wringer, just to squeeze out all the polish from many of the older guitars that come across my bench!!!

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If what you see is what you get, then Stevie Wonder ain't got nothin'!