M&T (bolt-on) Neck Angle

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RnB
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M&T (bolt-on) Neck Angle

Post by RnB »

Hi, I'm new here to the Forum.

Having been in limbo for a few years & things that I started some time ago...got away from me. So I'm going to try & pick up where I left off while trying to remember a few things. I have this figured Mahogany OM body w/ a cutaway & the back's already glued-up to it. I had braced the top (Italian Spr) & put it away & it warped slightly, but nothing that will restrict it from mounting to the top tight.

When I radiused the top of the body in the sanding dish, I think I got carried away & sanded too much off at the neck block area. Consequently, I believe the body thickness at the block is about .10" shallower than it should be for an OM? Dry mounting the top & neck on the body & running a straight edge from the nut to the bridge, the bottom of the straight edge appears to be 1/4" higher than the bridge (frets are not in yet).

I'm not sure where the the straight-edge should land, but where I see it now, it looks way too steep. Before I go ahead & glue-up the top, is there something that should be done to help fix the neck angle or can the angle be adjusted when it comes time to mount the neck? The neck is Martin one I got from Tippie & is a M&T (bolt-on). I plan to bind the fretboard which has long-style square & diamond inlays.

I'd like to complete this & move on to a kit I got from John about 5 years ago. It's a higher end kit than this Mahogany OM & I jumped into it w/o sufficient knowledge about building acoustic guitars. So, I put it aside. I'd like to get this one wrapped-up before trying to finish the fancier one.

Rich
Darryl Young
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Re: M&T (bolt-on) Neck Angle

Post by Darryl Young »

Rich, as far as the body being 1/10" more shallow than a standard OM, that will not be an issue. I doubt you or anyone else will ever notice this.

On the neck angle, some folks sand a 1 1/2 deg angle in the sides in the upper bout above the soundhole. Did you do any thing like this or only use the radius dish? What radius dish did you use, 15ft, 25ft, 28ft or what? Also, with the neck in place, does the fretboard lay flat on the soundboard?

We might be able to answer better if we have this info.
Slacker......
johnnparchem
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Re: M&T (bolt-on) Neck Angle

Post by johnnparchem »

If the fretboard is on the neck you should just be off the bridge a tiny bit. If you are a 1/4 inch above the bridge you will be way to high once you add the fret height plus the (action at the 12 fret * 2) to the 1/4 inch to get a saddle height.

When you took to much off the neck area you probable cut to much of an angle in to the body. I would check the angle of the body without the neck. You should be about a 16th off the body at the saddle location with a stright edge sitting where the fretboard extension would be. Fix that first. Then after the top is glued you can make any neck angle adjustments you need to make. If your body is angled such that you end up too high at the bridge you will have a ski jump when you adjust the neck for the right angle.
RnB
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Re: M&T (bolt-on) Neck Angle

Post by RnB »

Darryl Young wrote:On the neck angle, some folks sand a 1 1/2 deg angle in the sides in the upper bout above the soundhole. Did you do any thing like this or only use the radius dish? What radius dish did you use, 15ft, 25ft, 28ft or what? Also, with the neck in place, does the fretboard lay flat on the soundboard?
Yes, the fret board lays perfectly flat on the top. I'm pretty sure I used what Martin uses for their top radiusing - 28'...? I really don't recall off-hand. I will check & take a pic to show where the neck appears to be. I only used a radius sanding dish. Nothing else

I re-positioned the top tonite. It was slightly off kilter & it wasn't seating properly, throwing the alignment way off...my bad! I put the neck back on again & the neck angle is much better this time around. The straightedge now rests right atop the bridge wo/frets & slightly above w/ faux frets placed on top of the board to give an approx fret height. Does this look correct?
I would check the angle of the body without the neck. You should be about a 16th off the body at the saddle location with a stright edge sitting where the fretboard extension would be. Fix that first.
If such is the case, how would I go about fixing that...?

The body is going to be bound in ivroid to match the bound neck. I will try and post more pics as the build progresses. I'll visit here more often for solutions to what I'm not sure of, which is quite a bit...!

Thanx for this Forum John. it's been quite awhile.

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johnnparchem
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Re: M&T (bolt-on) Neck Angle

Post by johnnparchem »

looks like the angle is a little steep. The way I fixed this when it happened to me is I took a bit off of the rest of the body. I used a plane to take wood out of the waist, put pencil on to the top of the kerfing to keep track of where I was sanding and used a sanding disk weighted in the middle toward the tail to efedtly bring the body down effectivly lowering the angle.


I am sorry I am better at seeing issues than fixing them.
RnB
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Re: M&T (bolt-on) Neck Angle

Post by RnB »

johnnparchem wrote:looks like the angle is a little steep.
tippie53 wrote:The plane should be just off the top of the bridge .030 to .060 without the frets.
If I'm sitting atop the bridge w/o frets & slightly above w/ frets, wouldn't I be in the ballpark?
Seems contradictory here...?

Taking straightedge to the top w/o the fretboard on...from neck-block to tail-block, I have 1/16" space off the top at bridge area & 1/2" of space showing at tail-block...
tippie53
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Re: M&T (bolt-on) Neck Angle

Post by tippie53 »

I should edit that , you want , with the frets to be about 1/16 off the top ob the bridge.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
RnB
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Re: M&T (bolt-on) Neck Angle

Post by RnB »

I just took another measurement w/o frets & I have 3/8" space at bridge area. The straightedge is resting perfectly atop the bridge. I have a thinner bridge by .02", but I'd rather use the one intended for the build.
You want, with the frets to be about 1/16 off the top of the bridge
I'm guessing that frets would give me the additional 1/16" you're referring to...
Since I don't have the frets installed yet, would it appear that I'm w/in respectable range for the correct neck angle?
tippie53
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Re: M&T (bolt-on) Neck Angle

Post by tippie53 »

sounds like you are pretty close . I like to see 3/8 max without frets .
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
RnB
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Joined: Wed Jan 25, 2012 1:44 pm
Location: Bay Area

Re: M&T (bolt-on) Neck Angle

Post by RnB »

tippie53 wrote:sounds like you are pretty close . I like to see 3/8 max without frets .
Thanx John...! Once the top is glued & I'm ready to mount the neck, will I be able to make slight adjustments to correct the neck angle/alignment should it be off some?

I took a few pics when I 1st started this project & ran into a few issues. Somehow the side cracked in the cutaway, so I glued-in a patch on the inside. Then, it cracked/split again. So I put another patch in. In appearance, the fix looks rather shoddy. At the time, I made do! Also, apparently when radius sanding, one side got hit little harder than the other, as you can see (about .1"). But like Darryl said: Once, completed, it won't be that noticeable! Hell, ya say...

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