First guitar mistake -- I think

[Paul Eisenbrey]

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"Originally Posted on:"Thu Aug 12, 2010 "

Hi all,

I'm fitting the neck on my first guitar. Once I got the spacing right at the bridge, the fretboard rises to about 3 mm over the top at the rosette. It's flush with the top where the neck meets the side.

My question is this: What do I do? As I see it, my options are to
1) Glue the fretboard down to the top. I am afraid that will make the fretboard dive into the top, and make the frets up there hard to play (or to intonate),
2) Make a shim to slide under the fretboard to eliminate the space, or
3) Leave it as is, with the fretboard floating over the top.

Has anyone else made this particular mistake?

Thanks!

--Paul

[Lillian]

Do I have this correct? You've installed your neck at the correct angle so that a straight edge hits where you want it to at your bridge, but you have a gap under the fretboard at the rosette?

If I got it right, then I'd go with option #2, shim it.

[Dennis Leahy]

Can you take a few pictures and post them? Sometimes it really helps for others to help you if they can see the problem.

Dennis

[jeffhigh]

What Lillian says is spot on.
But 3mm rise over the length of the fretboard tongue is a lot
Have you fretted the board yet?
If you put a straight edge along the top of the fretboard extending to the bridge position, how high is it above the soundboard

[Ron Wisdom]

Did you build with a flat top or is it arched?

Ron

[Paul Eisenbrey]

Hi again,

I re-measured the gap, with my glasses on, and discovered I was wildly off. Rather than a 3mm overhang, it is just a hair under 1mm. Still too much, since I expected it to be flush with the top.

It is 11mm at the bridge, which matches the bridge I made.

As far as the design goes, I have been following Cumpiano's book, making the steel string. The top is arched slightly (perhaps not enough?)

I haven't access to a public server to post an image yet. I'll work on that next.

So: shim, glue, or let it float?


--Paul

[jeffhigh]

Is that 11mm with the straight edge resting on centre of the fretted board?
That would give you a string height of about 15 mm which is generally considered a bit high.
you may have a slightly high neck angle, which would give that high string height and the separation under the fretboard.

[Paul Eisenbrey]

Thanks Jeff,

Yes -- that's with the straight edge resting on the center, and the frets are installed. I stopped playing with the neck angle when the straight edge met the bridge blank.

It sounds like my bridge is too thick, at 11mm. That would explain the lift I'm getting on the fretboard. Rather than mess with my very rusty trigonometry skills, I think I should work the neck angle till the fretboard is flush, then thin down the bridge blank to fit.

I'm guessing that'll drop the bridge thickness down to somewhere around 9mm. Does that sound reasonable?

--Paul

[jeffhigh]

A 9.5mm bridge thickness is pretty common with about 3mm of saddle protruding above so that is what I would be aiming for.
Even if you dont get the end of the fretboard absolutely flush, there is no real problem clamping it down the last 0.25mm or so when you glue it, a bit of fall off beyond the body joint is fine.

[vandenboom]

From memory, I think Cumpiano recommends 3/8" for bridge thickness anyway, so I agree with jeffhigh....Frank

[kiwigeo]

Paul Eisenbrey wrote:

Thanks Jeff,

Yes -- that's with the straight edge resting on the center, and the frets are installed. I stopped playing with the neck angle when the straight edge met the bridge blank.

So you were resting the straight edge on top of the frets while adjusting neck angle?

How thick is your fretboard?

On my steel strings I adjust neck fit with fretboard off and aim for a straight edge run along the top of same to end up 10mm above soundboard at bridge position. String height above bridge can ne calculated by dialing in fretboard and fret thickness.

Im pretty sure in Campianos book he adjusts neck rake with the fretboard off and fretboard and fret up comes after the neck is glued in (he had to in his original book to fit the wooden dowels he used)

[Hesh1956]

Paul this may be helpful to you:

http://www.heshtone.com/

Fall-away is when the fret board extension gradually distances itself at a greater rate from the strings over the gutiar body. I like to see about .010 - .020" of fall-away at the last fret on a dread sized guitar. Purpose of fall-away is to help the guitar not buzz out from aggressive playing where the amplitude or lash of the strings is greatest.

Another important measurement is at the face of your bridge with saddle installed a good distance between the guitar top and the bottom of the low e string is about 1/2". Anymore and you have too much torque on the saddle that could split a bridge in time. Any less and you are not reaching the maximum energy level or volume that the strings could generate safely without tearing the gutiar apart. This 1/2" measurement is widely used by makers including C.F. Martin.

Remember too that a well built gutiar will be a bit of a living and breathing thing. If your humidity is swinging about and not stable the top or dome of the guitar will be rising and falling becoming a moving target for these precise measurements. A gutiar top can move in only a few hours if the swings are great enough....

Something else to consider too is that when you fret the fretboard extension or any fretboard for that matter back-bow will occur to some degree. At the extension the back-bow is greatest because of the closer proximity of the frets. This causes the unsupported fretboard extension to attempt to slightly curl in back-bow which also works for us in getting the sucker to lay down on the top. Make sense?

And lastly for now a tip to help you get that perfect neck joint is to NOT sand your binding on the top under where the neck and fretboard will go. Lots of builders forget this and sand the bindings rounding the bindings and then you have a gap where the neck, fretboard meet the guitar body.

[Paul Eisenbrey]

Posted: Fri Aug 13, 2010 12:27 pm Post subject: Thanks!

--------------------------------------------------------------------------------

I really appreciate all of the help you've posted. I think I know how to proceed from here: work the neck angle some more, to get that 9 to 9.5mm height at the bridge location. Let the fretboard overhang alone, and glue it to the soundboard once I have it in place. Thin the bridge down to fit, and mess up as little as possible while doing so.

Once it is done, I'll post pictures of the guitar for your amusement. It is definitely a newby's work. You'll be able to tell two things right off. First, I designed the body without sufficient research, and second, I have a lot to learn about bending sides!

Thanks again!

--Paul
_________________

[jeffhigh]

I'd go for 9.5 to 10

[Craig]

Paul , You say you're following The C&N book for instructions .

Page 304 deals with neck angles where he states No more than a 1/16 " air space above your bridge and no less than 1/64 th . Based on his recommended 3/8 " ( 9.53 mm.) bridge height , you want between 10 mm. and 11 mm. space at the bridge position using a straight edge on your fretted neck.

Going for the higher figure of 11 will hopefully give you 1/8 " (or slightly more ) saddle above bridge height . You'll find that extra saddle height very handy later when adjusting the set-up after it's played in a bit

[Paul Eisenbrey]

Thanks Craig,

I appreciate you pointing out the appropriate text. The only trouble I have with Cumpiano's book is that sometimes important information is buried in fairly dense text -- where I missed it, obviously.

I think I'm set now. Another week or so of French Polishing, and then I can fit, set, and attach the neck.

--Paul

[Localele]

Just relax Paul, it will all come together and you might be surprised how good it sounds. No.1 rule is to not point out any flaws to the general public when they are having a look. It is quite alright to do it here even with photos but not to the great unwashed who haven't experienced the agony and ecstasy of building.
Personally I hope you get to go through it all lots more times.

[kiwigeo]

Hey Paul,

As far as making mistakes go you have to beat my classic...on my first build I stuck the heel block on TOP of the neck blank. Luckily I realised before the glue had set.

Luthiery...the art of hidding one's stuff ups.

[vandenboom]

The stuff up I recall on my first guitar, following Cumpiano religiously, was to apply the fingerboard width of 14th fret 2 1/8" to the end of the fb. It was only after the guitar was finished that I realised what I had done.
The guitar plays fine but if you don't fret the high E fairly vertically, the string can slip off the edge!! I laugh every time it happens.
frank

[Dennis Leahy]

Localele wrote:

Just relax Paul, it will all come together and you might be surprised how good it sounds. No.1 rule is to not point out any flaws to the general public when they are having a look. It is quite alright to do it here even with photos but not to the great unwashed who haven't experienced the agony and ecstasy of building.

hahahahhaha Beautiful!

Dennis

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[Paul Eisenbrey]

Hi guys --

I meant to post photos of the finished guitar, then the site went down .

It has a
sitka spruce top,
IRW back and sides,
a maple neck (flat sawn from the lumeryard -- I don't recommend this, too heavy).
Rosewood fingerboard and bridge.
curly maple binding.

The odd shape is my attempt at design. I won't be doing that again soon. Once I actually know what I'm doing I'll give it another shot. Maybe 5 or 7 years.

It weighs a ton, due to the neck, but it sounds sweet!