Official Luthiers Forum!

I don't participate much in this forum, but I am planning my sixth build (all bolt on, most with M&T), and had a question about bolting down the fingerboard extension.

Assume that I want to build a simple butt joint 2 bolt with threaded inserts in the neck heel. Assume also that I plan on having an L shaped headblock with wood that extends to,and glues to, the upper transverse brace. I want to do a glueless bolt down of the fingerboard extension. I don't want to extend a rigid tongue from the neck under the extension this time. I have done that a few times already, and I want to try one that does not cantilever in that fashion (this time, anyway).

I see that some of you attach a 1/2" thick or so patch of wood under the extension, then put threaded inserts into that patch, and route a hole for the patch into the body of the guitar. I am interested in doing something different, and I want to see if you think there would be problems with this.

What if I simply inlay regular threaded nuts into the bottom of the extension? They are thin enough to not cause a problem with having enough wood left in the extension. I am thinking that the bolts that hold down the extension don't have to be cranked down all that tight; finger tight is probably enough. The virtue of this is that I would not have to route a hole in the guitar for a wooden patch to go into. The inlayed bolts (epoxied into place) would sit flush or slightly inside the extension. I figure 4 inlayed nuts would do the trick.

Anyway, I look forward to your advice. Thanks.

The bolts would need to be moderately tight. "Finger tight" nuts and bolts tend to vibrate loose after awhile. I've bolted a few bridges and usually put a little dab of epoxy on the threads to keep things in place.

Thanks, Clay. How about the other aspects of this idea? Do you see any issues? After building several guitars with a bolted mortise & tenon, and a stiff extension tongue, I want to see how things go if I don't have to either route big holes in the guitar or design them into the headblock. The idea of just drilling a few holes in the body appeals to me as a change of pace.

I know that the downside of the floppy extension is that it will not inherently stay in line with the rest of the fingerboard; a drop off at the 14th fret may be necessary to avoid a hump. For this particular guitar, I am willing to deal with that. I just want to give a simpler build a try and do some comparisons with the more complicated builds I have already done.

Thanks for any opinions or experiences that are shared.

How big are your inserts?

I have toyed with the idea of inlaying bolts into the extension with the threads poking down through the top, then using knurled brass knobs on the inside as fasteners.

I was thinking that a 10-32 bolt would be a good size for holding down the fingerboard extension. 1/4-20 (which is what I use for neck bolts) seems too big to me, and I worry about being able to easily manipulate anything smaller than 10-32 just by touch alone. A nut for a 10-32 bolt is pretty small. I'm not in my shop at the moment, so I can't measure one, but I know you can get nuts that are around 1/8" thick. I wouldn't have any trouble inlaying something 1/8" deep under a fingerboard extension. Since the bolt would bottom out in the nut pretty quickly, I would have to either buy or cut bolts to a precise length. That's no big deal.

This way of doing it would pull solid wood down onto solid wood; other than the bolt holes, there won't be any unsupported fingerboard area. As long as I don't crank the bolts too hard, they should do the job of keeping the extension snug against the top (no rattling), but not stress the fingerboard too much.

I think the worst that can happen is that it doesn't work, and I have to use a soft glue to hold down the fingerboard extension. But, again, I bet lots of you have experimented with similar bolt down methods, and learning what you think of this plan would be very valuable to me. Thanks.

Let us know how it turns out!

[quote=" Since the bolt would bottom out in the nut pretty quickly, I would have to either buy or cut bolts to a precise length. That's no big deal.

.[/quote]

Use a slightly longer bolt with a nut and washer on the shaft, bottom out the bolt in the insert, then just tighten the nut

Don, may I suggest that you should get in touch with Mike Baranik and ask him for advice.

Mike is the absolute doyen of this technique, and a really nice guy as well, so I am sure he will be able to help you.

Hi Don,
They say a picture is worth a thousand words.......
Don't miss the detail of the center spur of the Forstner bit having been shortened to where it just barely extends beyond the rim.
I use 8/32 thread. I prefer West System Epoxy but I have used various flavors with success.
I have used this method for 12 years without a failure. It is easy to execute, secure and the neck can be mounted/dismounted quickly.

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Kent Schoonover

WWW.schoonoverresophonicguitars.com

Sorry... the picture did not upload.

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Kent Schoonover

WWW.schoonoverresophonicguitars.com

Still no picture, Kent, but having looked at your website, I'm encouraged. You make some beautiful resophonics! I'm assuming the music is played on one of yours; sounds great!

So, you use 8-32 bolts, and that those are plenty big enough for the job. That's good to know. I can also see the "point" (pun intended) of lopping off the end of the Forstner bit before making the inlay holes. Otherwise, it could poke out the top side. Very helpful "tip".

Thanks so much for the input. I really appreciate it.

Here's one I did last year. There are two 8-32 T-Nuts epoxied into a recess in the fretboard extension. Two because I wanted one on each side of the truss rod. The recess was cut with a Forstner bit. One of the T-Nuts came loose after a few months because the glue joint failed. I simply drilled some holes in the flange and then re-epoxied it. No problems since. Sorry for the poor photo but that's the best one I had.



Here's what the neck block looks like. The top piece is a piece of 1/2" Baltic Birch. After the neck was fitted I used something with a sharp point to mark the fretboard and then put in the T-Nuts last.

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Steve Smith
"Music is what feelings sound like"

You could sink a couple of small bolts through the top of the fingerboard and secure them with nuts on the inside of the box. They could be hidden under position markers or wood plugs. Very small fasteners would be all that would be required.

Beautiful interior on that guitar, Steve. I'm curious as to how the combination of the different bracing pattern and the laminated braces works, but that's a different topic. It looks like the T-nuts work well. There should not be a big functional difference between those and the flat nuts I am talking about.

I checked with McMaster-Carr, and the nuts for 8-32 bolts are 1/8" thick. That's ideal for the inlay method, I think.

I appreciate all of the input, and look forward to more, if anyone else has experience with this. Thanks!

Don't want to sideline the thread, but looks like really neat work on the falcate Steve.

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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 was not able to get a photo to load but Steve's photo tells the story....

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Kent Schoonover

WWW.schoonoverresophonicguitars.com

Filippo--

I can talk about that now, that's fine.

My most recent guitars that I completed had rigid tongues under the extension, just cantilevered, and a barrel bolt mortise & tenon holding the neck on. These work great, but there are a few downsides. If I build with the mortise already in the headblock, keeping everything aligned during construction, such that there will be a good fit of the neck in the right spot, takes effort. I could wait and cut the mortise after building the body, but I'm not crazy about taking a router to the guitar that late in the game. I can do both of these; I am just not sure that I wind up with any better of a guitar for all that effort compared to a simple butt joint. As a player (these guitars are for me, not for sale), I don't freak out over a drop off at the neck/body joint. I rarely need the frets above # 14. I just don't want a hump that hurts the action. So, I would be OK with a more traditional extension, but I don't want to glue it down. Gluing is both harder to reverse if I want to adjust something, and it can lead to cracks in the fingerboard extension due to different swell/shrink characteristics of ebony and spruce.

I am nearing completion of a player adjustable neck angle type guitar, and it is very cool, but as a player, I am not sure I need that level of adjustability, compared to well made rosewood shims under the saddle. And building the adjustability into a traditional looking design takes a lot of work.

I guess what I am saying is that I want to try building the body, building the neck, drilling a few holes, and sticking them together, with minimal sweat invested in making sure everything will line up right when I am done. That will be a welcome change from the finicky things I have been building over the last 4 guitars, and I want to see, from a player's perspective, if the extra effort of the more finicky designs make a more desirable guitar.

Alignment of a butt joint guitar, with nothing sticking out of the bottom of the extension, should be easy. In fact, everything about what I am proposing seems easier in the abstract. So, I want to try it out and do some comparisons.

That's the goal. I appreciate all of the help. Keep the input coming!

Thanks Colin. The epoxy is harder to keep neat than any other glue I've used, that's for sure. That was my first and only falcate so far, it came out ok but I did a few of my own experiments during the build that I feel did not help things. I'll do another one but will follow Trevor's plans much more closely next time; better to learn to do it correctly before one starts making changes.

Don, if you use the T-Nuts I recommend you drill holes in the flange to give the epoxy something to hold onto. I had used a grinder to rough up the surface of the T-Nut and that was not sufficient, one of the epoxy to metal bonds failed and had to be reglued.

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Steve Smith
"Music is what feelings sound like"