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Neck angle
http://www-.luthiersforum.com/forum/viewtopic.php?f=10101&t=46609		 Page 1 of 1
Author:  Les [ Wed Nov 04, 2015 9:44 pm ]
Post subject:  Neck angle
Good evening
After figuring out my neck angle, I cut my tenon and mortise, and they fit very nice, now my question is this. When I do a mock setup with a fret board I have to force down the part of the fret board that rests on the guitar body. Did I do something wrong?

Thanks....Les
Author:  J De Rocher [ Wed Nov 04, 2015 10:18 pm ]
Post subject:  Re: Neck angle
How large is the gap between the sound hole end of the fretboard and the top?
Author:  meddlingfool [ Wed Nov 04, 2015 10:37 pm ]
Post subject:  Re: Neck angle
Not in my opinion. It depends a lot on how you approached your geometry. As long as you don't have to press it down too far, you've built in 'fallaway', which is good. I aim to have to press the fingerboard tongue down. I want. I needs it. My precioooouuuussss....
Author:  Les [ Wed Nov 04, 2015 11:29 pm ]
Post subject:  Re: Neck angle
From the top of the sound board to the top of the fret board, is about 3/8", which leaves about a 1/8 gap.
Thanks for the quick replies.
Author:  DannyV [ Wed Nov 04, 2015 11:44 pm ]
Post subject:  Re: Neck angle
Sounds like the neck angle is out. With the neck in place, fb sitting in place, if you place the bridge onto the appropriate spot you should have about a 32nd gap over thr bridge. The bridge should have the top radius on it. That should give you a better idea of what's going on.
Author:  Mike OMelia [ Thu Nov 05, 2015 12:00 am ]
Post subject:  Re: Neck angle
If ur top is domed, this is expected. Sand flat as can or dare the contact portion. At an angle commensurate with the bridge height. I do this with a longish piece of granite that has sandpaper glued on it. Put a dummy bridge in expected location, then sand contact area while riding dummy bridge. Think about the geometry. However, if u underestimated neck angle, this will only get u so far. Then, sand ledges of neck to make the angle right. Done correctly, fingerboard should not bend to meet top.
Author:  J De Rocher [ Thu Nov 05, 2015 12:01 am ]
Post subject:  Re: Neck angle
Like Ed, I aim to have to press the fretboard extension down to meet the top. In my case, I aim for a gap of 1/32" or less. Others may do it differently though.

This is after having sanded the contact area flat by a method similar to the one Mike described above.
Author:  Mike OMelia [ Thu Nov 05, 2015 12:14 am ]
Post subject:  Re: Neck angle
My comments assume a domed top. Plus, be careful that you don't take anything off of the edge at the neck joint. I think folks call this "flattening the dome" ?? If anything, if u already fretted the fingerboard, the FB extension should bow somewhat down (if at all). This can be a complex issue to attack. You need to be Sure this isn't due in part or whole to neck angle inaccuracy. But a domed top naturally means you will telegraph that curvature to the FB extension unless u carefully remove any dome in the contact area.
Author:  Les [ Thu Nov 05, 2015 1:14 am ]
Post subject:  Re: Neck angle
Once again thanks for all the help. My top is flat, I used Jonathan Kinkaids book to figure out the angle, l guess I am out on the angle.
Author:  bluescreek [ Thu Nov 05, 2015 7:06 am ]
Post subject:  Re: Neck angle
A fall off of a few thousandths maybe a 1/64 a 1/8 is telling you that something isn't right.
Author:  Hesh [ Thu Nov 05, 2015 7:29 am ]
Post subject:  Re: Neck angle
New builders tend to assume that if we do everything as the resource that we are using says correctly that zip, zam.... all the parts will fit flawlessly.

Wrong.... R - O - N - G.....:)

Necks have to be fitted, always.... and that 1.5 degree neck angle that some of us discuss from time to time is only an approximation.

There are several toots in the instructional section of the forum such as "Fitting a neck" and "flattening the upper bout" that will help you, Les. Perhaps give these toots a look and then let us know how we can help?

Thanks.
Author:  Tom West [ Thu Nov 05, 2015 8:21 am ]
Post subject:  Re: Neck angle
A big part of the correct set up for the neck is accomplished in the correct building of the box before one even thinks about building the neck and fitting it. Good write up in Trevor Gore's book. Sure worth a look if you can get your hands on one.
Tom
Author:  kencierp [ Thu Nov 05, 2015 8:41 am ]
Post subject:  Re: Neck angle
With a few exceptions Kinkeade's publication is very good. Unfortunately the major exception is that some of his geometric concepts fail the math test. Your problem stems for the fact that there is no upper bout slope machined on the rim to match the neck angle. Like has been mentioned, a little fall off is acceptable and for some even preferred. But pinching the FB extension down to the soundboard can be problematic. Here's my explanation of what needs to be accomplished.

http://www.kennethmichaelguitars.com/neckangle.html
Author:  Mike OMelia [ Thu Nov 05, 2015 11:19 am ]
Post subject:  Re: Neck angle
Ken, why would some prefer it? To me it just looks bad if there is an obvious bend. Also I am unclear on what you mean by "slope machined onto rim". My slopes are machined onto the neck ledge at the M&T joint.
Author:  Mike OMelia [ Thu Nov 05, 2015 11:30 am ]
Post subject:  Re: Neck angle
Les wrote:
Once again thanks for all the help. My top is flat, I used Jonathan Kinkaids book to figure out the angle, l guess I am out on the angle.


Install neck with FB attached. Bolt it on (assuming not a dovetail). Lay a long straight edge on FB and extend to bridge. Where does it contact the bridge. Top edge? A little bit above? Below?

Some pictures would help. Do not press FB down during the test or picture taking. If you built in a 1.5 deg or so neck angle, and your top is truly flat and your sides are truly square, then I do not see how you avoid the bend.
Author:  kencierp [ Thu Nov 05, 2015 11:33 am ]
Post subject:  Re: Neck angle
Mike regarding the slope --- it would be easier if you read the article which has been around for many years, it explains how to manually accomplish what is done at the Martin Factory (even pictures) using power equipment.

Personally I like using the straight line formula -- but some like to sand some fall off on the extension and others (like Kinkead) pinch and glue the FB extension down to the sound board. The way I understand the latter, is that some minute additional clearance is achieved allowing a little lower action at the 12th fret.
Author:  Mike OMelia [ Thu Nov 05, 2015 1:44 pm ]
Post subject:  Re: Neck angle
Ken, are you talking about this? http://www.kennethmichaelguitars.com/neckangle.html

I see what you mean by slope on rim now.

Mike

EDIT: I never saw the link you posted above... I must have thought it was a signature line... sorry
Author:  kencierp [ Thu Nov 05, 2015 1:58 pm ]
Post subject:  Re: Neck angle
Yes sir, that's the one.
Author:  J De Rocher [ Thu Nov 05, 2015 4:23 pm ]
Post subject:  Re: Neck angle
Mike O'Melia wrote:
Ken, why would some prefer it? To me it just looks bad if there is an obvious bend.


In my case. since the gap at the end of the fretboard is less than 1/32", there is no obvious bend. You can see the fallaway if you place a straight edge on the frets or sight down the length of the neck, but not otherwise. Which is normal if fallaway after the 14th fret is intended. As I see it, you can introduce fallaway either by reducing the heights of the frets above the 14th fret or by building it into the fretboard extension. By doing it with the extension, those frets remain full height so you have the option of filing them down later to reintroduce the fallaway should it be needed after years under string tension.
Author:  Les [ Fri Nov 06, 2015 12:07 am ]
Post subject:  Re: Neck angle
After reading KMG neck angle instruction, it cleared up a lot of ignorance on my part. After a little shimming, gluing and recutting the tenon and mortise to the proper degrees I got the FB to sit down on the sound board.
Thanks to all who helped me out.........You all have been a wealth of knowledge.

The guitar that I am building is a copy of a Baden guitar, so with that being said I do not have any plans that I am actually following, rather a little off this drawing and a little off an other drawing, plus my own measurements off a Baden guitar.
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