# Design Help: Neck Lengths And Such

Discussion in 'Luthier's Corner' started by SpecialBomb, Jun 18, 2019.

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1. ### SpecialBomb

Sep 11, 2018
USA
Hello!

I am attempting a bass design sometime this summer, and I have been planning it out in CAD. It's a prototype bass that I may hope to produce someday if I ever am able to (Steinberger/Chapman inspired minimalism, but less brutalist). I may make another post regarding my design and whether my choices towards it are sensible or not (I'm trying a lot of different things with it that hopefully benefit the player). It has all went smoothly so far, but I've hit a large rock in the road.

Before I explain my problem, it's important to know that I am modeling my bass off of a 34" scale length, and using a neck pocket for a 20 fret Jazz Bass neck (I don't have the skill or resources to make a custom neck).

The issue comes when I try to place everything on the body, like the pickup cavity and where the bridge will be. Essentially, I can never know where to place anything in relation to the nut or bridge, because the neck pocket is dependent on the length of the Jazz Bass neck. If I was making my own neck and pocket, this wouldn't be an issue, but it seems I cannot find the actual length of a jazz neck from the nut to the very heel.

Am I missing something here? Do I absolutely need to know the dimensions of the neck in order to properly align where the bridge/pickup is? I'd imagine there is some sort of logical/mathematical definition for the nut-to-heel length of a jazz bass, but I haven't seen it.

2. ### MPU

Sep 21, 2004
Valkeala Finland
You need to know the distance between nut and bridge and nut and 20th fret. For those you can use fret calculator, like Fret Position Calculator | stewmac.com
The heel is a bit longer than 20th fret so you need to have the neck for accurate neck pocket drawing.

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3. ### Will_White

Jul 1, 2011
Salem, OR
Using the calculator MPU posted I use 21 frets as the end of the heel, also since you're using a cad program place the bridge off the nut or the 12th fret.

Last edited: Jun 18, 2019
4. ### Arie X

Oct 19, 2015
scale length-it's all that really matters and it's a fixed dimension. measured from the inboard side of the nut to the center of the 12th fret (octave) x 2. yes, there is compensated string length but it's on the order of 1/8"~5/32" inch or so (depending upon gauge) and that's what adjustable saddles are for.

a quick and dirty way i suppose of approximating heel to bridge length would be to get your bridge and your neck, place them on a table at the correct scale length and measure from the bridge plate to the heel.

online fret spacing calculators can give you fret to fret measurements but if you have a neck you can measure that yourself as well.

once you understand scale length it all comes together.

5. ### SpecialBomb

Sep 11, 2018
USA
Yeah, that's what I guessed. However, I am away from home right now and can't actually make measurements on the heel. I wish this was a little more defined, lol. I'm just antsy to keep working on this design since I've been wanting to get it out of my head for a while now.

6. ### SpecialBomb

Sep 11, 2018
USA
Well, yes, but the problem still persists. There is a missing dimension, which **is** the neck. Because of the unknown dimension of the neck, there is no telling how large the body needs to be. When I say body, I am referring to the length from the bottom of the neck pocket to the end of the scale length. Obviously the size is limited by the position of the neck pocket and bridge, so that dimension is needed for the design to actually be fully constrained.

Imagine it as two lengths that add up to 34", and I don't know either of them. As a result, the joining point between those two lengths is variable, because that joining point (in relation to the nut) could be anywhere without having a fixed neck or pocket-to-bridge length. The scale length can't help here, unless the length of the nut to the heel of the neck is aligned somehow to the scale length, like Will_White suggested. Either way, I really can't find a fixed dimension for it online, lol.

7. ### Will_White

Jul 1, 2011
Salem, OR
You can also work off the 20th fret and ignore the heel until you can get a measurement. It doesn't effect much unless you want a pickup right at the end of the neck.

8. ### ScoopsWhy do we use base 10 when we only have 8 fingersSupporting Member

Oct 22, 2013
Sugar Creek, Wisc
OK,

Take the neck you are going to use.
Measure the distance from the 12th fret to the heel end of the neck. It should be about 6.5". Position the bridge saddles pieces about 10.5 from the heel end of pocket on bass.

9. ### Bruce JohnsonGold Supporting MemberCommercial User

Feb 4, 2011
Fillmore, CA
Professional Luthier
I'll just confirm that almost all Fender (and good quality clone) Jazz necks are 34" scale and the end of the heel is cut off right at the 21st fret line.

The distance from the front edge of the nut to the end of the heel is 23.89". So the standard distance from the end of the neck pocket to the Zero Line of the bridge needs to be 10.11".

The Zero Line is the theoretical end of the scale length. If you are drawing this all up in the computer, adjust the position of the saddles most of the way forward on the base plate. With the saddles in that position, position the bridge so that the saddle fulcrum points are right on the Zero Line. That will put the bridge in the right place. When you adjust for intonation, you'll always be moving the saddles back away from the neck, anywhere from 1/8" to 3/8". You need to allow for that travel of the saddles.

With all that said, if the actual neck you are getting isn't a genuine Fender or has mysterious origins, it may be trimmed off slightly shorter than the 21st. Or it may not even be exactly 34" scale length. If you have doubts, you need to measure the actual neck to confirm the dimensions.

10. ### SpecialBomb

Sep 11, 2018
USA
Thank you, this is really useful, although I would like some serious comfrimation that it gets cut off at the 21st, since I was comparing dimensions from Warmouth 21 fret jazz necks because they have an overhang. The heel didn't seem to align at the 21st.

I am finally home now, and I measured two official jazz bass necks that I have. They consistently measured about 6 7/8" from the 12th fret, or 23 7/8" in total from the nut to the heel. I feel this will be a good base point for me to actually start finishing my prototype, even if it isn't the official length. Thank god for moveable bridges.

I will be modeling the bridge I will be using soon, which is a hipshot bridge (part 5A4FM1). I know its a drop in for a fender mount, but they are like 75 dollars on amazon, and that's a lot better than 120 for the hipshot 4 screw mount version of the bridge. Luckily, the maximum and minimum intonation points are listed in that pdf, which is nice, so I'll be able to design this based off numbers alone. CAD can kinda suck sometimes if you are designing independently, because model files don't always exist openly.

Either way, I'm super excited to make this thing. It's going to be the big thing I do with my dad before I move out, and I'm expecting this to be my main bass for the rest of my life. I'm also going to design a strat version of this design, and give it to him one day for fathers day, and I am already excited about that. Of course, this is only Mark I of the design, so it's based off external parts, Mark II (or whatever I get to in the future) is going to have hardware and a neck completely designed by me.

Thanks for everyone's help <3

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12. ### SpecialBomb

Sep 11, 2018
USA
I hope I even get to the point of building it, I need to find someone or someplace willing to let me borrow a CNC router.

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13. ### charlie monroeGold Supporting Member

Feb 14, 2011
Buffalo, NY
Do a search for a ‘makerspace’ In your area.

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14. ### SpecialBomb

Sep 11, 2018
USA

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15. ### Bruce JohnsonGold Supporting MemberCommercial User

Feb 4, 2011
Fillmore, CA
Professional Luthier
I suggest that you use your computer to design it and make up drawings, then use hand tools (including a normal router) to make it to your drawings. Feel the thrill of craftsmanship! A power tool straining in your hands as an arc of wood chips flies. The exhilaration of smoothing out the body with a big hand file. The satisfaction of measuring what you just cut, and seeing that it does match the numbers on your drawing.

Tapping some keys on a keyboard, and watching a CNC machine buzzing away gets boring fast.

16. ### SpecialBomb

Sep 11, 2018
USA
Pft, I WISH I had the tools to do that properly, but I don't, and my dad hasn't really done something like this before. We're on a budget, and if we mess up, it's not exactly cheap to throw away some messed up stock along with having to pay for all the tools, bits, all of that.

Some of the stuff will still be done by hand, like cutting out pickguard material to cover the electronics cavity, adding a fillet around the edges to smooth out the body, sanding and finishing, and drilling a few holes for hardware. Don't worry, some humanity will be involved. I also find what you've said to be a little ironic to me, as this is a prototype for a bass/guitar that I am hoping to mass manufacture one day, if I even get on the map. The whole idea here is to minimize the amount of material and complexity of the body so that same money can be put towards nicer hardware/electronics and a much better neck.

17. ### The Ryantist

Mar 7, 2010
Orange County, CA
23 7/8 = 23.875, which is only 0.017" off from the theoretical 21st fret. That's about half the thickness of a credit card, likely within your measurement error, and definitely within the range of your adjustable range. You'll be fine

18. ### SpecialBomb

Sep 11, 2018
USA
A quick update, I am having trouble finding someone or some place that will help me get the body routed out. Thankfully, my parents are awesome and are looking at options themselves, which is a big help. The design is fully completed, but I had to do a few changes to make room for the electronics I'm adding. All of my parts have arrived, and they are super nice!

I got a SMB-4A Seymour Duncan stingray pickup, a Hipshot 5A4FM1 bridge in brass, Schaller S locks, and a Switchcraft 3 way switch.

My plan for the electronics is to use the 3 way to select between the bottom coil, top coil, or both for humbucking. It's a stingray pickup, but I love how they sound passive and EQ's are stupid expensive. I even tried designing my own EQ circuit a while back, but that didn't really go anywhere. I won't be using a volume knob, since I don't find them that useful, but as compensation I will be adding a mute switch. The body is very very small, so ill have to see what extras with the electronics I can add since I don't even know if I can manage to get a mute switch to fit in there.

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19. ### Beej

Feb 10, 2007
Vancouver Island
20. ### dwizum

Dec 21, 2018
That's the brand of the piezo and mic buffer I put in the hollow body I finished recently. I have a bunch of their stuff in other instruments, too - jacks, passive wiring harnesses, etc. I haven't use their preamps specifically but I wouldn't hesitate to. I would agree with your assessment. Lots of options, cheap, works well, but definitely not fancy or "high end" in the build/packaging/branding.

Plus the guy that imports those is more than happy to help, get specs from the manufacturer or ask them questions, swap single parts or change options, etc. Much more helpful than many other "cheap imported parts on ebay" shops I've bought from.

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