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Working on a new neck design - thoughts?

Hi all,

I've been thinking recently about the design I use for my necks, which is currently neck-though, with a recess carved out. As I use homemade boxes with thin lids, I need to accommodate bracing on the underside of the soundboard, throw pickups in the mix and I have a serious weak point. One of my 4 stringers has developed a bow, and I believe it is coming from the recess.

This is the recess cut out for a 3 stringer with a homemade box - this one is still solid but you get the idea of how much material I need to remove to allow for the fretboard standing proud of the soundboard, and also the bracing underneath.

The neck wood I have most easily available is oak, in lengths of roughly 1 metre, here is a proposed design in which the neck is cut and re-glued into supports.

[Apologies it's so poorly rendered - 5 minutes in Paint!]

The overlap forming the heel would be maximum about 150mm/6", the blocks underneath would be the same width as the neck, glued to the box and screwed from underneath to the neck - do you think this would be strong enough for a 3 or 4 stringer? (I haven't ventured into truss rods yet, nor do I have a router.) I feel that this needs to be the direction I move in so I can start messing about with resonators etc. without compromising the strength of the neck.

Your thoughts as always would be greatly appreciated.

Rick

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Permalink Reply by ChickenboneJohn on January 23, 2014 at 8:21pm

Looks OK, you just need to watch how much depth you've got left under the pickup cut-out, and in particular how much gluejoint overlap you have at the heel position - the longer the better to give you good mechanical strength. You don't need to glue and screw, a properly clamped glue joint is fine as long as you've got truly flat gluing surfaces. Here's a video where I touch on this subject, (from about 3m30s into the clip) but with set-in necks rather than thru' necks, but the principle is the same in terms of leaving enough thickness at the heel.

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Permalink Reply by Richey Kay on January 23, 2014 at 8:33pm

Thanks CBJ - that's really helpful. I'll get the ruler out and see how long I can make the heel. I was considering buying some of your fretboard blanks, incidentally. Are you able to cut them lengthways? I don't have any power tools here and they're a bit wider than the neck blanks I have...

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Permalink Reply by Slowpaw Steve T on January 23, 2014 at 8:31pm

you maybe should be staying with the through neck with one piece of wood, Richey - the flaw in your proposed design is in the diagram, where the neck joins the body, a weak point, also adding more bracing wood adds mass to the whole body therefore reducing the ability for the whole guitar to resonate and sustain, if you strum a chord the whole length and body should be resonant.

the neck should still go through in one piece, cut enough recess to accommodate the lid of the box only, and glue a piece the length of the box beneath it and the floor of the box to brace it without adding too much mass, and it will be rigid.

Using Oak, the neck will be strong enough for normal 4 string playing and will not bend unless you put pressure on it!

this design is my own opinion, it is good for acoustic and electric and works for me (-:

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Permalink Reply by Richey Kay on January 23, 2014 at 8:37pm

Thanks Slowpaw - although by necessity I need to remove a lot of material from the neck for the bracing underneath the box, pickup etc... plus I wanted to have a go at making a reso guitar, and this wouldn't be possible with this design, which is similar to what I use now.

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Permalink Reply by ChickenboneJohn on January 23, 2014 at 8:58pm

Richey - message me about neck blanks - I'm tooled up with a surface planer and a thickesser so can reduce stock down to whatever thickness and width you fancy. I've just posted up a video on how I do reso guitars..,I don't want to give away too many of my secrets, but you'll probably get the basic idea.

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Permalink Reply by Richey Kay on January 23, 2014 at 9:21pm

Will do mate - will be treating myself next month. I sent a friend request and I will PM you.

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Permalink Reply by Slowpaw Steve T on January 23, 2014 at 9:52pm

no the design for a Reso would be completely different, a frame to hold the reso cone but only use as much wood as you have to, and extend the shoulder piece along the neck (-:

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Permalink Reply by Slowpaw Steve T on January 23, 2014 at 9:56pm

i eliminate the need to cut deeper into the recessed neck for a pickup by fitting Flatpups or Piezos, with the strings bridged just high enough to clear, though with the brace glued undreneath it should still be strong enough without bowing (-:

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Permalink Reply by the anonymous pick on January 23, 2014 at 10:05pm

just another thought before you go through all those hoops .. make sure it is actually " bowing" that is happening ,, and not just ( box lid compression ) .. lid being spooned in a bit due to downward string pressure on the bridge and a space under the box lid .

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Permalink Reply by Richey Kay on January 24, 2014 at 2:07am

Good point Pick. I'll measure it tonight but the soundboard is pretty solid with good bracing underneath...

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Permalink Reply by Richey Kay on January 24, 2014 at 8:47am

I just checked and there's a dip of less than 1mm in the middle of the box. I'm sure it's a bow as a dip would surely make the action lower at the bridge end of the fretboard - mine is too high. Pretty sure I just need some more solid bracing inside.

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Permalink Reply by Yankee Dog on January 24, 2014 at 1:15am

Maybe you have too many strings. : )

Or maybe your scale length is too long. I have a 28" three string that is starting to bow after a couple of years under tension.

But also, be aware that the more braceing you have that touches the box, the more it will deaden vibration and your sound. No that big a deal in an electric device, but you will lose acoustical volume.

from your photo, it looks like you have also cut down the thickness of the neck outside the box. The added fretboard should help alleviate this??? Is the fretboard glued or screwed?