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I'm considering a bolt on for guitar #2. It occurred to me that the fretboard could be attached with double sided tape for ease of removal. Thoughts?

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Hutch

Get the heck off the couch and go build a guitar!!!!

Tape gets unhappy in tension. I think if the fingerboard is pressing down on the soundboard the idea makes sense to me. Or just a dime-diameter dot of glue.

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Peter Havriluk

How about magnets?

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Hutch

Get the heck off the couch and go build a guitar!!!!

I use double sided tape for the fingerboard extension on my butt joint bolt ons for trial fittings. It doesn’t hold very well. For the finished guitar, I use Titebond. It’s pretty easy to release it with heat and it holds pretty well until you want it to release. Without gluing down the fretboard extension, the fretted notes up there are pretty weak.

^
Same

Just a small bead of glue around the perimeter of the fingerboard extension does fine. Easy to undo, The no need to slather up the entire extension and glue the whole thing.

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Jim Watts
http://jameswattsguitars.com

Yep ^

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

I vote glue ‘er down too

You shouldn’t need to remove the neck very often but even if you do need to, it’s a quick job to apply heat and loosen the extension.

My process is: once finish and neck fit is good, I bolt the neck on, leave the extension unglued and string up to pitch. If the neck fit is good and the geometry of the instrument is right, the extension will be lying down flat and tight on the upper bout and look as if it was glued at this point anyway.

I leave it under string tension a day or so to give things time to settle in so I know exactly what the saddle height/bridge rotation will be at pitch. Usually, I’ve already got the geometry well set so no tweaks are required, but in the rare case that something screwy manifests, it’s trivial to adjust neck angle at this time. If all looks good, I remove the strings and glue the extension down. This extra step is all just me being paranoid.

You shouldn’t need to touch the extension or bolts again unless a neck reset is needed at some time in the distant future, at which point it is a relatively fast and simple process to restore optimum angle.

Titebond for me. I recently reset the neck on my pine 1-18 that I built over 10 years ago. Loosened the bolts and left the fingerboard glued in place. A few flossing swipes of sandpaper on each side and perfect again!

Yep, I've been able to get around 3/32 action adjustment without having to take off the tongue...

Titebond, Hide Glue or Fish. I use Hide glue now but have used all of them. I have had the pleasure of removing a couple of mine many years later and it's a cinch. Just don't glue the hell out of it.

I don’t know if others have noticed this but a glued vs.say a Bourgeois type double tenon bolted extension seems to have a small stabilizing effect on movement post string up.

I have noticed that on a neck reset with a bolt on neck everything can look just right strung up with the extension unglued and after gluing it there is a little less movement resulting in the need for a slightly higher saddle.

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

I build from Cincia classical RM Mottola plan with bolt on neck. The extension fretboard tight with plastic bolt but I cnage with ebony wood bolt.
https://www.liutaiomottola.com/instrume ... ocId739648

Good info, thanks Terence. I’ve had limited exposure to the double-tenon style so have never compared. I’ll look out for this if one arrives on my bench.

I also noticed this- I do mine a bit different than Bourgeois but it made a big difference when I made sure the front (edge towards the soundhole) of the extension fit tightly in the front edge of the pocket. i.e no room to move forward.

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Burton
http://www.legeytinstruments.com
Brookline, MA.

The shear strength (I think) of the glue really helps prevent forward rotation of the neck. I remember the first guitar I made with a bolted tongue came back to the shop with the action at .140.

I abandoned the design in favour of a glued tongue.

Glue or bolt down the fretboard extension. The fretboard extension should be considered a structural brace in a critical location. It ties the neck to the heel block and the upper transverse brace. Including the top you have 8-9 mm tall wide brace helping to keep the neck from bending forward hinging on the body join. It is really cheap in time and effort even over the life of the guitar to just glue it down.

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http://www.Harvestmoonguitars.com

meddlingfool wrote:
"The shear strength (I think) of the glue really helps prevent forward rotation of the neck. "

Indeed.

I recently did a bunch of measurements around tuning the 'neck mode' of a couple of classical guitars. If the lowest whole-body resonance of the instrument matches the Helmholtz-type 'main air' mode it can affect the sound of the guitar. I was able to check this out on several 'master' instruments, and found that such an alignment was normal for some of them. This mode is most influenced by the taper of the neck; making it thicker up at the body end raises the pitch, which is normally too low. When building on a solera it's fairly easy to tune this, since carving the neck is one of the last major steps. The question was whether I could do the same with a bolt-on.

Even with the neck left rectangular and thick I was getting neck mode pitches that were low when they were just bolted on. On a hunch, I tried wedging the fingerboard extension up, and that raised the neck mode pitch. I decided to try bolting the neck on for good at that point, gluing down the extension with my usual dot of hot hide glue. That raised the pitch a fair amount, and I was able to carve them from there and get the modes to match fairly well. I'll note that adding the mass of the furniture bolt and cross dowel nut to the finished guitar dropped the 'neck' pitch significantly; at least a half semitone, so I may go back to gluing necks on Classicals when not using the solera.

So, yes, gluing the fingerboard extension does stiffen it up usably. Who'd have thunk it.

I like the idea of fitting the neck tenon snugly against the front of the mortise. I usually leave a little gap.

What I did do that helped was leaving a small gap between the end of the integral headblock extension and the top brace and after cutting the mortise for the fretboard tenon using the exposure that granted to very tightly wedge a wood filler in that gap between the extension and top brace. I put it in really tight without glue and then wick in thin CA to hold it.

It definitely helped the movement but I would still like to see it better. I will try the snug mortise trick. Thanks Burton! Do you leave a little gap until everything is the way you want and then shim it to make it snug?

The double tenon neck has so many advantages I like I hate to abandon it.

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

I have never tested this and in fact wish I read this before just yesterday I glued down the extension on my current project so I could try it but... I Have always considered gluing down the extension as part of the neck joint system over all.

cutting corners is not a way to make a good guitar.
make a better bolt on neck

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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

I didn't think of it as cutting corners, I was thinking , we have some pretty strong double sided tape available. As I think on it, heat would still be needed to release that so a little glue is just as good or better.

I can't decide on the best bolt on for a first attempt. I know if I do a bolt on, I'm going to want to take advantage of it at the first inkling of high action. The double tenon has really got my attention but the ease of a bit of glue has got me flip flopping.

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Hutch

Get the heck off the couch and go build a guitar!!!!

Sarge Mario once posted that he just used a small puddle of glue under the extension for easy release and I then did that too forever more and it's worked great for me with four dozen or so guitars that I did it to.

There are a number of possibilities. The best non-glue bolt-on design I have seen (this is my opinion, and opinions vary) is the Gore/Gilet design, outlined in detail in their books.

In terms of simplicity and functionality, however, I think a regular two bolt design (either with a straight mortise/tenon or a butt joint) and a glued down fingerboard extension is a great design, if you can live with a partially glued joint. Gluing that part solves a lot of issues, and it is pretty easy to reverse.

I think a butt joint requires a larger heel which I'd rather not have. The mortise and tenon seems like a better option for keeping the heel smaller. Does that matter, probably not.

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Hutch

Get the heck off the couch and go build a guitar!!!!