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Questions about building my first neck


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Mates,

I have and will do my homework before asking, but since I trust this forum, I would like to pose questions for advice or confirmation,  and get assistance with issues along the way. I am sure there are many variables I have not considered (you don't know what you don't know), so maybe you could even rescue me from the edge of the cliff! Of course,  I will post progress photos.

I am going to attempt a 24.75" bolt on neck with an angled headstock using a scarf joint. I was thinking about a top glue for the scarf so that the seam is under the fret board. I want a double action truss rod accessible at the headstock. It will be used to replace an import neck on an prior tele build, so it will join the body at the higher frets (around 17-18 I think?)

OK, first question: 30" seems to be adequate for this endeavor.  Can I go less? I found some nice 27" blanks! However, I think the top glue method will cause me to sacrifice about 2 inches.

Second question: is a 17.25" (438mm) truss rod a good choice? I think this would bring me to the 21st fret.

Thank you for any advice 

 

 

 

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Your best bet is to do a 1:1 drawing of your neck on paper and work out where your joint will be, the angle of the joint and the length of the blank you will need. It is a lot easier to just stick an extra bit on the underside of the headstock than do a scarf if you want to make your life easier for your first build - you could hide that joint on top and bottom with decorative veneers. One of the reasons I stick to one piece necks, although the material costs slightly more, it's a lot less work than worry about cutting scarf joints.

438mm truss rod should be fine for a 24.75" neck 

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34 minutes ago, ADFinlayson said:

Your best bet is to do a 1:1 drawing of your neck on paper and work out where your joint will be, the angle of the joint and the length of the blank you will need. It is a lot easier to just stick an extra bit on the underside of the headstock than do a scarf if you want to make your life easier for your first build - you could hide that joint on top and bottom with decorative veneers. One of the reasons I stick to one piece necks, although the material costs slightly more, it's a lot less work than worry about cutting scarf joints.

438mm truss rod should be fine for a 24.75" neck 

Thank you for the advice! When you say to stick a bit extra on the bottom, do you mean a thicker blank and a fall away headstock, or a volute, or something else? How thick of a neck blank would I need?

I do want to be able to produce angled headstocks. I am an not a fan of string trees.

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Yes something like this.

2008887307_ScreenShot2022-05-26at15_36_29.thumb.png.89e7a825a268e9a59e08239edc2c3e6b.png

I think the average strat/tele neck is around 21m thick at the heel but required thickness would depend on the depth of the neck pocket and the height of the bridge on the body you're already using, That's why it's often easier to start by building the neck then building the body to suit. 

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You could always laminate an extra piece onto the headstock offcut if you're worried about the length being too short after you've cut the scarf (same timber species or different for contrast) , or even use a headstock piece from a different cut of timber altogether and place the scarf cut as far up the blank as possible..

8 hours ago, ADFinlayson said:

Your best bet is to do a 1:1 drawing of your neck on paper and work out where your joint will be, the angle of the joint and the length of the blank you will need.

Or do it mathematically.

Say you want a 14 degree back angle using a 25mm blank. To find the amount of extra length that will be added past your scarf joint just find the length of the red line:

image.png

sin 14deg = 25mm/unknown length, solved for the unknown length = 25mm/sin 14deg = 103mm.

If you want a neck that has 24.75" scale length (aka 628mm), just subtract the 103mm from the required length of the neck. So if you were shooting for a full 24 fret neck first work out your required neck length: 628 / 2 = 314mm [ie, distance from nut to 12th fret] plus 314 / 2 = 157mm [ie, distance from 12th fret to 24th] = 471mm. Call it 490mm to allow for some fretboard overhang at the end of the neck and for some human error while making your scarf cut.

So if you place your scarf cut 103mm back from 490mm you'll be able to work out how much extra you have to play with for the headstock once cut:

image.png

To work out how much of the headstock face you'll get after you flip the cut piece over, just do the trigonometry on the triangular horizontal length and subtract it from the 298mm back length above:

image.png

 tan 14deg = 25mm/unknown length, solved for the unknown length = 25mm/tan 14deg = 100mm.

Therefore headstock face length once cut and assembled = 298-100 = 198mm:

image.png

image.png

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It's the sort of thing you could throw together into an Excel spreadsheet if you really wanted. Feed in the thickness of your blank, desired scale length, required headstock length and headstock angle. It does all the heavy lifting for the math and spits back out the position of the scarf cut and a minimum blank length needed to achieve your design, plus any extra tolerances required for things like fretboard overhang, nut shelf, saw blade kerf, wobbly hands etc.

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3 hours ago, curtisa said:

It's the sort of thing you could throw together into an Excel spreadsheet if you really wanted. Feed in the thickness of your blank, desired scale length, required headstock length and headstock angle. It does all the heavy lifting for the math and spits back out the position of the scarf cut and a minimum blank length needed to achieve your design, plus any extra tolerances required for things like fretboard overhang, nut shelf, saw blade kerf, wobbly hands etc.

Your explanation was excellent, thank you. I t caused me to look at the issue without the shortcuts and brought me to a better understanding. It also made me realize that I need a plan before I purchase blanks 

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On 5/26/2022 at 4:17 PM, ADFinlayson said:

One of the reasons I stick to one piece necks, although the material costs slightly more, it's a lot less work than worry about cutting scarf joints.

For the same reason I like laminated necks! Just a bit of extra length and you'll get two sturdy necks out of two slabs and some slats.

image.thumb.png.897ea1fbf2b12d7a28475cb8805ed37d.png

 

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Both should work. A band saw is most likely the more common choice simply because few of us have access to a big miter saw with a fine toothed blade but if you have one and know how to use it, it should do a more precise work.

Make use of the tools you have and master them!

And just in case your sawing goes all off and you'd need to straighten your cut, an angled sanding/routing ramp can help!

image.thumb.png.ba95d1c8026cb290afad5de3103e4ced.png

 

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2 hours ago, Bizman62 said:

Both should work. A band saw is most likely the more common choice simply because few of us have access to a big miter saw with a fine toothed blade but if you have one and know how to use it, it should do a more precise work.

Make use of the tools you have and master them!

And just in case your sawing goes all off and you'd need to straighten your cut, an angled sanding/routing ramp can help!

image.thumb.png.ba95d1c8026cb290afad5de3103e4ced.png

 

Good advice, thank you.

I do need to make one of those sanding jigs. 

I am not close to a master of either band saw or miter saw, but I am willing to learn...usual the hard way!

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8 hours ago, RVA said:

I was going  to make a jig for my bandsaw fot the scarf joint cut, but it seems like a miter saw is a better option.  Thoughts?

While a miter saw is accurate it does not accommodate the angle you need without making a jig for it.

mk

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6 hours ago, MiKro said:

While a miter saw is accurate it does not accommodate the angle you need without making a jig for it

Good catch! I didn't think about that a mitre saw only can cut up to some 50 degrees either way.

There's several videos about making a jig for any angle, this one seems to have all the information without going back and forth. One of the biggest issues in cutting long and narrow pieces like a plank is to hold the piece perfectly upright. A taller jig would help as you can lean your piece against it.

 

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6 hours ago, RVA said:

This beast seems like it can cut any angle you may need with the bevel adjustment. It is capable of tilting from 0 to 48 degrees in either direction 

Yep, all the jigs are already built into the base! That would be a neat tool for mass production, maybe a bit expensive for a one-off neck?

There's quite a lot of five star reviews but some of the critical reviews at Amazon were umm... interesting.

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2 hours ago, Bizman62 said:

Yep, all the jigs are already built into the base! That would be a neat tool for mass production, maybe a bit expensive for a one-off neck?

There's quite a lot of five star reviews but some of the critical reviews at Amazon were umm... interesting.

Cool, thanks for the feedback.

I always think that tools will come in hand eventually. Something like this keeps my fingers away from a table saw for a myriad of projects. In retirement, I hope that wood is my biggest concern. I have a nice little wood shop going now - 10" jointer, 13" planer, 14" bandsaw, router table. None of them get enough use to justify what I spent on them, but the limited use I gets makes me happy, which is what it is all about in the end. Hey, I think I just justified a CNC machine!!

Edited by RVA
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all in my humble opinion... if you take any miter saw... esp a sliding miter saw... and you try to move the blade/handle left/right... they move quite a bit.  a while back I was looking at a $500+ dewalt and thinking of setting it up to do fret slots... went to the local store and checked them out... was shocked at how much movement is there.  for that reason... I just do not see this as a great candidate for cutting a scarf... at least not reliably.  ymmv.

for that reason, and contemplating a scarf myself in the very near future... I watched a number of table-saw-scarf-jig videos on youtube.  below is my plan for the design for a table saw jig to do the job. 

I have a infinity super general blade for my saw that I have used to do the body joint on my last few builds.  pull it right off the saw, no sanding, and glue up.  the jig I use for that just is a simple board with some hold downs and a zero play rail.  I tell you this not to say "yer doing it wrong" or anything, but more so that in case you are in doubt about it at all... this might be another option.    

 image.thumb.jpeg.79d142f5f18197f2d201f99fdf06fd1e.jpeg

this is one of the joins right off the saw before glue up:

IMG_2787.thumb.JPG.94c98babbc8c224b19e06231a090c50f.JPG

 

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