Official Luthiers Forum!

The machine that Martin uses to slope the rim is show here, a little way into the article. I saw this in person, the top edge is sanded 90 degrees to the rim, rim tipped 1.3 degrees and a slope is sanded flat from about the edge of the sound and includes the entire neck block. Is this what you are calling fall away?

http://kennethmichaelguitars.com/neckangle.html

We seek to emulate this process in our tooling and kit materials.

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Ken Cierp

http://www.kennethmichaelguitars.com/

kencierp, that is exactly what I am doing now, or trying to do anyway. You suggest one degree. How do you get that? I'm sure I could do the trigonometry but it might be easier to ask. So how mush lower is the head block relative to the rim plane after you impart this angle?

A couple of different methods

http://www.kennethmichaelguitars.com/ri ... angle.html

http://www.kennethmichaelguitars.com/rimslopeMM.html

and here's a video

https://www.youtube.com/watch?v=sy7ieraU-Ns

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Ken Cierp

http://www.kennethmichaelguitars.com/

I do the same which does not result in a fall-away. I just can't find any need to have a fall away. My first good view of a dead straight neck was on a Burgeouis (sp?) cutaway. From nut to end of fb, it was straight (only a tad of relief). I've aimed to make all mine this way. Alternatively, one time I was in the local guitar store and 5 out of 6 Ovations had so much wave, hump, fall-away in the neck I don't see how they were playable (certainly could not set them up with low action).

Now I understand and the answer is no. What you are doing, I do it as well differently, is what I call flattening the upper bout. For me I do this to contibute to a smooth, gapless transition of the fret board extension over the body with of course no hump or unnatural acts required for fitting. The process how I do it also contibutes to matching up the body to a 1.5 degree neck angle and 25' top radius, what I use.

Although when I flatten the upper bout it automatically contributes to fall-away so long as my fret boards are not thicker at the ends fall-away is a different thing.

What fall-away is is the deliberate milling of the fret board extension and/or specific building methods that manipulate how the fret plane and string plane interact and where. It has nothing to do with the body although some things that we may do in how we build may impact fall-away for better or worse. The benefits of fall-away Dave will attempt to explain far better than I could.

Also regarding fall-away some folks don't require it. Shredders with a light touch are one example and I can play shredder guitars myself just fine having both a light touch and I can play like a gorilla as well. But many players do benefit a great deal from fall-away and some require it.

More to come.

Does fall-away compromise intonation on the upper frets somewhat? I know that's a pretty important thing for a lot of electric lead guitar types.

No James, it doesn't.

I actually dislike the term "fall-away" since it kind of implies a visually perceptible drop-off at the 14th fret ... that's not what it is about.

My experience over the years is that the optimum set-up is achieved when, with the strings on, and the guitar strung up to pitch, and the desired amount of relief dialed in, a straight edge laid along the fret tops contacts the 1st and the 14th frets, and just clears the remaining frets on the fretboard extension.

I wouldn't dream of offering advice to builders as to how they would achieve this in the building process,... all I know is that when I get a guitar in the shop, that is how the fret tops get treated ... sometimes it leads to the upper frets ending up a few thou lower than the lower frets ... no big deal.

I like to see just a touch of fall away if that is what you want to call it. On martins , the neck block is set with the grain direction , the same as the sides. This ,and that the top can swell up in hi RH a little is more in favor that a rise for sure.

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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

What Murray said! I also agree with John as well.

For us the only difference from Murray is that we want the straight edge to contact the 1st and 12th with the desired relief in between with of course a bit more relief on the bass side and less on the treble side. After the 12th until the last there is a gradual falling away of the fret board until the last fret may be approx. .015" lower than that straight edge sitting on the first and 12th. The amount of fall-away or what ever we want to call it is not as important as having some fall-away as opposed to having none.

A perfectly straight fret plane works too with players with a light touch but a moderate player or heavier will need some fall-away or the action will have to be higher than it has to be with fall-away.

How the player attacks the strings has bearing here too. Some folks can play very low action without slinging the strings into the frets, some can't.

If you use what I am describing here with the 12th being the fret where we begin the fall away you can see that it also can't be confused with a body-joint hump in that the 14th will be a few thou lower than the 12th hence no hump. This is of course for 14 frets to the body and on a 12 fret guitar fall-away still starts at the 12th but now it can be confused with a body-joint hump.

What's understandable here is that builders tend to be building centric with concerns about body joint humps, the transition to the body of the extension etc. Repair folks tend to be fret-work centric knowing with experience that one set-up does not work for all but some fall-away will work for all if not most. So when the end user for an instrument is yet to be determined I always build mine with fall-away or what ever we want to call it and using the Martin idea of flattening the upper bout that I believe John does too if I recall correctly produces an instrument that most anyone can play.

Ringo/James (I want to call you what you want to be called my friend so let me know and I will make it so) fall-away has no perceivable impact on intonation. There is a very minute change in distances because of the very small about of fall-away that math will verify but nothing audible to humans and likely tuners either.

Don't get me wrong I'm not a fall-away evangelist but I do induce it on my stuff and every fret dress and refret that I do. That's a LOT of instruments by the way and it's been my experience that even the very most demanding players benefit from it and in many instances the set-up that a player desires would not be possible without it.

I lucked out through no effort of my own when I started flattening the upper bout because with my neck angle and top radius and a flat upper bout I automatically seem to get the desired fall-away through nothing intentional on my part. It's nice when things go well even if we did not intend the results that we received. Also with OMs, L-OOs, dread*ughts, and SJ's the specs I have provided all produced fall-away between .008 and .015ish.

I modeled a compound curvature fretboard with Aspire and I cut my fretboard on the cnc. I have a negative ramp starting at fret 12 and ramp down to 0.015 at the 21st fret. With the compound curvature and the 0.015 fallaway, I never have a buzz problem.