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I’m not quite there yet but should be in a couple weeks. I have seen there are several methods for setting neck angle. For this guitar I am using the Cumpiano mortise and tenon. I see that the angle should be that when a straight edge is held on the fingerboard it should be just touching the bridge top surface. I was almost wanting to install frets prior to fitting the neck so that could eliminate my opportunity to use that method. Good idea or bad to install frets prior to final fitting of neck. And of course I still need to do the finish work as well.

Everything has been going good on this first guitar so far, but now I’m questioning the sequence of work in the neck setting / finishing / freting stages.

When I used to fret the FB off the neck, I flossed the neck joint so that the top surface of the neck itself projected with the straight edge to about 3mm above the soundboard at the saddle position.
This assumes a 6 mm FB and 1 mm fret height.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

I would add that setting the neck angle should be thought about before closing the box in terms of sanding the rims, UTB radius or whatever method you choose. Ideally you want to have the plane of the upper bout under the FB extention angled as above, i.e. to project 3 mm above the soundboard at the saddle position.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Double check the book again, I'm pretty sure that Cumpiano's method has you install the frets first then measure for airspace at the bridge.

I install frets after the neck is attached because it allows you to resurface the FB if necessary, sometimes you might get a very slight, or an exaggerated one if you don't plan the neck set into your rims, at the body joint.

I would add that setting the neck and should be thought about before closing the box in terms of sanding the rims, UTB radius or whatever method you choose. Ideally you want to have the plane of the upper bout under the FB extention angled as above, i.e. to project 3 mm above the soundboard at the saddle position.


This is where the technique of sanding the top side at the upper bout at a slight angle (about 0.125" at the end block) on a flat surface comes into play. This will help to ensure that the neck angle is correct. I do this for all my builds...

However, I have found that I never quite know exactly whether I have sanded enough or too much. The technique calls for, after driving the bus to establish the proper radius, chalking up the kerf lining, elevating the end block 1/8" and sanding until the chalk is removed to the equivalent of the sound hole location.

Does anyone have any guidance on when you have sanded enough and established the desired angle?

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Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

If you are planning to do a standard tapered heel, (ss) the Cumpiano process is flawed. It has you cut a 3° (If I’m remembering correctly) bevel where the heel meets the body. If you are doing a straight/parallel heel this is not as much of an issue. If doing a tapered heel that 3° bevel will place the fretboard plane way too high at the saddle location (ask me how I know). This will force you to have to remove material at the top of the heel rather than at the bottom. This is much easier to do with the fretboard off. You can also deal with this by cutting a compound angle to compensate for the above issue.

Hope this makes sense, M

If I'm setting neck angle and haven't fretted the board yet I stack three business cards on each end. They are approximately 10 thousands thick (each) so thats pretty close to the height of the fret plane.

Here is Hesh's (remember Hesh?) method from 2010:

http://www.luthiersforum.com/forum/viewtopic.php?f=10117&t=25931

Ed

You can measure with frets on, fretboard on, or bare neck...just remember to add fret height, fretboard thickness, etc. as appropriate. Bare neck plane over saddle position is likely about .085"-.095. Add fretboard thickness to that if measuring with a bare fretboard. Add fret height to that if measuring with frets installed.

The graphic below illustrates the relationships...once it is understood, it's possible to measure in just about any configuration (bridge on, bridge off, fretboard on, neck fretted, etc.).



FWIW, the Cumpiano rule (i.e., on surface of bridge) works because bridge thickness plus 1/16" is what we look for with frets on, so without frets, the straightedge ends up close enough to the surface of the bridge to call it done.

If you want to progress beyond rules of thumb and can suffer through learning the geometric relationships expressed in the graphic (and can do addition, subtraction, and ratios), you'll be able to build for any desired combination of string height at saddle, bridge thickness, saddle exposure, etc., and able to work out both heel trimming allowance for the installed bridge on neck resets or replacements.

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For the times they are a changin'

- Bob Dylan

Are you thinking of the 5 degree cheek bevel angle called out for the steel string neck in Cumpiano? I believe he calls for the tenon to be milled square to the fretboard plane and the cheeks back-angled for better fit to body; however, given that his body templates call for the steel string neck area to be dead flat through the 3" width of the neck area, the net impact is to angle the neck back about 1.2 degrees (assuming a 000-depth body at the neck). In any case, I don't see how the end angle of the tenon would influence neck back angle, given that angle is established by contact of the cheeks with the body.

If Cumpiano had called out that beveled cheek cut as necessary to establish the correct neck back-angle relative to the body, it would have been a bit clearer as to why the operation was done. The other issue with this method is that - when combined with commercial plans that call for curvature through the neck area - the 5 degree cheek angle will likely not adequate to establish the necessary ~ 1.5 degree neck back angle that a top with some dome will need to achieve playable action.

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For the times they are a changin'

- Bob Dylan

Hi Woody

Agreed, in my case it took it too far and requiring me to remove material from the top of the heel which would have been much easier had the *fretboard been off the guitar*. It only happened once. That was about 40 instruments ago. I think the Cumpiano book is a great place to start for the beginning builder. I still use things I learned in there.

Best, M

here are 2 videos that should help
1 https://www.youtube.com/results?search_ ... t+addendum
2 https://www.youtube.com/results?search_ ... tal+set+up

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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

This question comes up every time I log on to check out what is new here.
Building guitars is fun but frustrating if not planned out correctly. Mixing methods from different books and tutorials can lead to getting stumped when it might be too late.

If the body is being built separately from the neck and it is complete, the angle of the neck heel to body is already determined.

An important, maybe critical part of making a guitar with a fretboard that sits on the guitar body and projects to the bridge correctly is to set the angle of the upper bout. This has to be or has been done before thinking about the neck heel angle.

There are work around methods like planing the fretboard at a slope and other things like bridge height or adding a wedge under the fretboard.


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Ken

Short version of descriptions I've seen of how Martin does it: Sand entire upper rim flat and square to the body (meaning top is 90 degrees to the neck block). Elevate front of body 1.3 degrees. Sand flat back to the soundhole. Put complementary angle on heel, so that the sum of the two angles is 180 degrees. That makes the plane from neck to body flat (no fallaway, no ski jump). Then install the top. Devil's in the details, but this can be a measured and predictable process if neck and body measurements are valid.

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Peter Havriluk

We routinely see extremely tall bridges on relatively new Martin instruments (0.425" on an M a few months ago, and an even taller bridge on a Mexican-made instrument), as well as bridges that are just a bit thicker than 0.300" - a nominal 5/16" which ends up shorter than that with a 0.020" (!!!!) bridge rabbet. While at one point, Martin may have used just three bridge heights (5/16", 11/32", and 3/8"), this fourth required thickness (7/16"?) appears be the consequence of accepting an astonishingly wide range of outcomes in a modern factory-made instrument.

We see about 0.040" total variation in final string height (and thus, related bridge thickness) on our own guitars and most custom-built instruments which come in for work. We suspect that most of that range is due to variability in body distortion under string load, so I have to wonder what is it that Martin is doing that drives them to fix body angle issues with an assortment of required bridge thicknesses versus a change to their process?

In summary, it seems to me that there are better approaches to establishing body and neck geometry than what Martins appears to have settled for over the last 40 years or so.

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For the times they are a changin'

- Bob Dylan

First you guys whine about the bridges being in the wrong place, now you're whining about how tall (or not) they are. Next thing you know you will be whining about the "limited" lifetime warranty.

Funny you should mention that...Martin recently ditched 'lifetime' neck resets, etc., and the little stuff like repairing binding that falls off the guitar in a few years...which makes sense, given the string of warranty-driving oppsies that has bedeviled the company over the last decade. Oh...my...here I go offering a valid critique...er, whining again.

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For the times they are a changin'

- Bob Dylan

I think you meant to elevate the tail 1.3 degrees. By The way, try measuring 1.3 degrees accurately.

This only works if the bracing of the top is accurate to the plan, consistent, and FLAT in the upper bout. And there is not considerable springback. Additionally, the stiffness of the body, especially the top, can and will change the whole shootin match.




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Ken

Just on the question of how to measure 1.3 degrees: in this context, it is easier and more accurate to measure offsets at specific distances from the neck/body joint (like at the bridge location and at the tail block) rather than trying to make sure a 6” long protractor is set precisely at 1.3 degrees. We can describe that angle as being in the 1.3 degree range, but precision comes from being careful about the amount of offset you get at those important spots.

Right Don! Hopefully the newer builders will read this.


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Ken

One thing you can do that is pretty accurate is to place an elevated pivot point right where the front of the bridge will be. The height can be wherever you want your straightedge on an unfretted board to hit the bridge unstrung.
I set mine at bridge height as I am looking for 1/16” over and this builds slight fall off in the upper bout which usually almost goes away under string tension with my neck attachment system.

Use a sanding board that has a piece of 1/4” plexiglass attached to the bottom to mimic the fretboard and sand the angle into the upper bout. Works pretty well. Charlie Hoffman and Jim Olson who used non-radiused tops had a router jig to put the angle in the rimset using the same principal.







I usually do it after the back is on as everything is more rigid. After the box is closed you can fine tune things with the Fox paddle if needed.



This approach has worked for me.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

That’s what I do. Guess where I got the idea [WINKING FACE]

Jim’s geometry has rendered a shallower neck angle. The taper he puts on the upper bout is 0.75 deg.

Something newer builders need to understand is the geometry of the entire working plane between the nut and saddle and all the dimensional factors that come into play. I can’t remember how many times I drew out all these things on cad the first guitar I built. It took time to fully understand. But now that I do, I don’t worry about it as much. This is where having good jigs comes in. Make sure the jig is perfect and you don’t need to worry that much anymore...



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"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

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We've built with the wedged upper body and with a brace-forced upper body geometry. The forced geometry seems more consistent, but both work. A summary of the forced geometry approach for any of the shapes we build (Size 5 to 12 fret dreadnaught), 28' radius X, tone bars, fingers and bridge plate glued into a 28' radius dish, and a 60' radius UTB glued on a flat caul gives proper extension fit with no flattening on 14 fret and minor flattening on 12 fret.

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For the times they are a changin'

- Bob Dylan

Woodie—

With the brace-forced approach, are the sides profiled for the top with a 28’ radius dish, or is something else done?

The assembled rim is radiused for the top at a uniform 28' - flattening the rim in that area is not necessary to achieve the top geometry.

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For the times they are a changin'

- Bob Dylan