5-string fretted for Eric

[SDB Guitars]

Building a 5-string fretted for one of my good friends, Eric. He's coming to visit in 7 weeks, to stand in my wedding to Dr. Girlfriend.

In an attempt to speed things along, I started by "re-engineering" a neck from a previous build. Here's what I started with:



It was a neck for a 6-string fanned-fret project I was working on years ago, and I made the neck taper too narrow at the nut. It's just a few mm over what you'd want on a P-spaced 5-string. SOOOOOOooo, I figured I could re-engineer it for this 5'er. More on that in a bit.

I had a nice one-piece burled and mildly-figured Claro Walnut top ~15" wide. Here it is, wet with a little water (pardon the camera phone pic):



I had a medium-weight mahogany board that I used to make the body blank:



Here they are together, with the shape traced on the top, and the body blank glued up/sanded/cut out:



So, on to the neck. Because this was a 37" - 33.25" fanned fret neck, it was way too long for a 35" scale neck. Couple that with the headstock that is too narrow, and I decided that something has got to go. I started with the fingerboard:



I made a jig to hold the fingerboard parallel to the feeder belt on the Performax 1632, as seen above, and fed it through until the fingerboard was completely planed off:



Once I had the fingerboard off, I removed the truss rod. I routed an oversized channel in the neck to clean it up, and then inserted a 1/2" wide by 3/8" deep purpleheart filler strip. The original truss rod was accessed at the neck pocket end, and I wanted to convert this to have headstock truss rod access. Here's the filler strip installed:



I initially thought to shorten the neck at the heel end, and square up the headstock, and add new wings. however, the more I thought about this, the less likely it seemed like it would work. I talked to Eric about what he wanted in a bass, and his biggest concern was that he wanted to have headstock density in order to try to avoid the "G-string 5th fret dead spot". The width at the heel was about 6mm over, I had some room to trim there. So, I decided to cut off the headstock (and a couple inches of the neck, too), and glue a new one on. I used my 13° headstock jig to do the deed, making sure that the neck's centerline was completelylevel on the jig, so the cut would be perfect:



Here's another angle... you can see the assymetrical carve on the back of the neck, it's thinner on the treble side:



I was originally going to try to replicate all of the neck laminations through the new headstock, but decided that in the interest of time (and frustration level) it would be better to let that go. Because he wanted more weight/density at the headstock end, I kinda took the route Warmoth uses on their lam-neck headstocks. I used a single piece of fairly heavy hard maple for the headstock core, which will then get a set of wings attached (probably bloodwood). Here I am gluing the new headstock onto the neck:



...and here's the result:



Used my truss rod jig to route the truss rod channel... nothing new to see here!



Decided that I wanted the headstock access to be nice and clean, so I made a jig to drill straight through the headstock into the truss rod channel, as opposed to routing the channel clear through into the headstock:



Another angle on the jig:



And the result:



More pics to come. Need to order hardware and pickups, still, so this is definitely a work-in-progress...

Thoughts?

[Thumpin_P]

Very cool sir!! Looking forward to the next installment. Very interesting to re-purpose a neck! Good luck and thanks for the details thus far!

Thumpin_P

[Darkstrike]

Awesome stuff.

[octaedro7]

May I ask you:
Why you wanted to change the TR access? What are the pros of having a headstock access?
Was the TR originally glued?
Also, couldn't you have tried to extract the fretboard with heat?

Thanks in advance

[roberthabraken]

Very cool build! This is all new for me, refurbishing a neck that thoroughly. Really interesting and informative!

[SDB Guitars]

Originally Posted by octaedro7

May I ask you:
Why you wanted to change the TR access? What are the pros of having a headstock access?
Was the TR originally glued?
Also, couldn't you have tried to extract the fretboard with heat?

Thanks in advance

The truss rod itself was not glued, it was a commercial dual-rod/dual direction setup.

The decision to do headstock access was mostly one of convenience, as it requires Allen wrench access, which due to this particular rod's design, was problematic to access from the body side. If I were making the rod myself, it would have a spoke wheel style nut, and would be accessed at the body end.

I could have removed it with heat, but I glued it with poly glue, which would have required planing or sanding to remove anyway, so I figured I would just do it all together.

I am currently talking to the customer about going in a different direction. Haven't had much of an opportunity to work on this lately due to life and the day job, and now winter is coming. 3rd day I. A row with frost on my car... >_<

[octaedro7]

Thanks for the explanations Shawn. I don't picture the difference in accessibility between both when it comes to use an Allen wrench, though. Care to elaborate?

[roberthabraken]

Originally Posted by SDB Guitars

Looking at your pics more closely, I noticed that your original truss rod configuration with the adjustment nut at the heel, does not extend all the way to the first nut. I would rather like to have the adjustment nut at the heal, but since I want a 24 fret neck, I felt the commercial available rods were too short. Somehow, I imagine the most important part to control bend is the thinnest part of the neck, being the first few frets. But since I see you've done it, maybe you can tell if it's okay to do so? And does this differ when I'd use carbon rods that do extend all the way to the first fret?

[SDB Guitars]

Originally Posted by octaedro7

Thanks for the explanations Shawn. I don't picture the difference in accessibility between both when it comes to use an Allen wrench, though. Care to elaborate?

The access at the heel was deep enough that it was difficult to get the allen wrench in there, you had to use a T-handle allen wrench to reach it. Additionally, as mentioned below, the truss rod did not reach all the way to the nut, which I am not comfortable with.

Originally Posted by roberthabraken

Looking at your pics more closely, I noticed that your original truss rod configuration with the adjustment nut at the heel, does not extend all the way to the first nut. I would rather like to have the adjustment nut at the heal, but since I want a 24 fret neck, I felt the commercial available rods were too short. Somehow, I imagine the most important part to control bend is the thinnest part of the neck, being the first few frets. But since I see you've done it, maybe you can tell if it's okay to do so? And does this differ when I'd use carbon rods that do extend all the way to the first fret?

See above - The truss rod is, as you mentioned, most needed in the first 5 - 7 frets. Because I was using a commercial rod, and an extra long scale (37" multi-scale on the original neck), I determined that it would not be stable, that's part of the "re-engineering" of this neck. CF might have helped, but in the end, I'd rather start over from scratch and have a neck that is properly supported. I spent a day or two attempting to re-engineer this neck and re-purpose it as a 35" scale, but I am currently talking with my friend about just starting from scratch. Have a couple of ideas in the works that I want to prototype on his bass that, if they pan out, will probably become standard on my instruments.

[roberthabraken]

Thanks, good to know. I'm following every detail here, very cool

[octaedro7]

Thanks Shawn.
Yeah I realize that there are like 10 cm of neck not covered by the TR when the access is @ the heel, and as Rob mentioned, for slim neck profiles it would be really nice to not have to access the TR where there's less wood. I see that being the TR nut on the lower rod makes the access with the wrench really difficult in a 2 action TR.
Still there are a couple of things that I cannot help myself thinking (because of my limited experience):
With necks made from hard woods like Wengue, purplehart, padouk, etc, plus fingerboards made of hardwoods too, will these 10 cm, that are not in reach of the TR, but in turn have all the wood that the TR channel would have taken out, will that really be a weak spot, a bending point?
What about if you on top of it use CF rods and you place them starting at the very nut.
I really wonder if even without the CF rods you would have problems.
Again, I lack of experience so I'm all ears

[pilotjones]

Originally Posted by octaedro7

Thanks Shawn.
Yeah I realize that there are like 10 cm of neck not covered by the TR when the access is @ the heel, and as Rob mentioned, for slim neck profiles it would be really nice to not have to access the TR where there's less wood. I see that being the TR nut on the lower rod makes the access with the wrench really difficult in a 2 action TR.
Still there are a couple of things that I cannot help myself thinking (because of my limited experience):
With necks made from hard woods like Wengue, purplehart, padouk, etc, plus fingerboards made of hardwoods too, will these 10 cm, that are not in reach of the TR, but in turn have all the wood that the TR channel would have taken out, will that really be a weak spot, a bending point?
What about if you on top of it use CF rods and you place them starting at the very nut.
I really wonder if even without the CF rods you would have problems.
Again, I lack of experience so I'm all ears

The job of a truss rod is not to strengthen the neck. It is to shape the neck.

Putting strings on a standard neck results in too much forward bowing. This needs to be reduced, to achieve the slight forward bow that is a standard neck relief. The truss rod does this by exerting a rearward-bowing force.

If the TR is absent in some part of the neck put present in others, then this reshaping can result in an unusual and undesirable shape, which will reduce playability.

[octaedro7]

Thanks Pilot. I was hoping that you jump in
I know that the purpose of the TR is to control bowing (although if it's helping the neck in opposing resistance to the string's tension semantically is adding strength, but don't want to go there, is kind of a wankery discussion)
What I'd like your help with is in understanding the interaction between the TR and the CF rods. There are 2 things I struggle the most:
If the CF rods are adding stiffness to the neck, aren't they somewhat interfering with the TR action?
Under the situation I described on my previous post, if 2 CF rods are placed starting from the nut towards the body, and if the TR is placed from the heel towards the nut, leaving +/- 4" between the end of the TR and the nut. Shouldn't the CF rods prevent this deformation you described? How do you think the interaction would be in this case?

Sorry Shawn if you find the discussion out of place. In fact it may...

[Mister Know Not]

It is very cool how it's done.
Very good craftmanship.
But I can't help thinking, why not make another neck and use this beautyfull neck on another build, there was alot of work in that neck also.
I know you said it was for gaining some time, but, this wasn't done in a few hours eather, I think.
For me, this way would be more work, than glueing another neck.
But, than again, I don't have those very nice tools you got.
Very nice shop you have.

[pilotjones]

Shawn, I hope I'm not overly tangent-ing your thread by answering.

Originally Posted by octaedro7

What I'd like your help with is in understanding the interaction between the TR and the CF rods. There are 2 things I struggle the most:
If the CF rods are adding stiffness to the neck, aren't they somewhat interfering with the TR action?

No - in a conventional case, they help the TR.

Consider it this way (I'll be slightly misusing "force" where "moment" would rightly apply, but I'm not writing this for an engineering audience):

The neck has a certain stiffness. Stiffness can be defined here as resistance to bending from an outside force. If you mount a beam projecting out sideways and add a weight at the tip, and it bends downwards 1/4", it has a certain stiffness; if it is twice as stiff, it will bend down only 1/8" under the same weight. This stiffness is increased by adding reinforcing (CF or steel) rods.

The strings exert a force to bend the neck forwards; the TR to bend it backwards. These add together and partially cancel out to make a net force. Normally, the TR force is slightly less than the strings' force, resulting in a small net forwards force.

The desired end result is a slight forward bow (relief). To get this, there must be a slight net forward force.

The stiffer the neck is, the greater the net forward force must be to get the desired result.

So, this means that in a less stiff neck, the TR must be tightened more, in order to cancel out more of the effect of the string; in a stiffer neck, the TR can be tightened less and so do less work, because it doesn't need to cancel out as much of the strings' effect, since it is harder to bend the neck in the first place.

Under the situation I described on my previous post, if 2 CF rods are placed starting from the nut towards the body, and if the TR is placed from the heel towards the nut, leaving +/- 4" between the end of the TR and the nut. Shouldn't the CF rods prevent this deformation you described? How do you think the interaction would be in this case?

Hmm, the situation is complicated. To start with, in a plain standard neck, the neck gets less stiff as you go from the body to the headstock, because of decreasing width and depth of the beam. But, at the same time, the bending moment also decreases in that direction, do to reasons that are too complex to go into here.

If you add a TR and optionally reinforcing bars, that go the whole length, then it at least seems a natural solution. It's definitely one that has worked.

Your proposed situation where coming out from the body there is first TR bending applied, then a zone of TR bending and CF stiffening, followed by a zone of CF stiffening but no TR bending, is something I'd want to avoid if possible. That said, it's slightly possible that it could result in a relief shape that's even better than standard, and just hasn't been done yet. But not for me. Somewhat related, Hans-Peter Wilfer of Warwick has a patent using CF reinforcement that varies in thickness along the neck length, in order to achieve some shape as a goal.

[bassist4dalord]

Ultimate Best Man/Groomsmen gift. Very nice!!