Custom scale guitar measurements

[newuser1]

I've done quite a few electric guitars over the last few years (of various quality ), however I always used templates for the neck and body for each of the guitars. I've varied the shape of the guitar body sometimes, but I still used templates for pickups and neck pockets.

I'm planning on doing a 4-string tenor guitar with 20" scale and I don't have any templates for that. My approach is the following, and my questions are in bold:

1. Calculated neck length for 20 frets using https://www.stewmac.com/fret-calculator/

20

13.700"

0.375" (19-20)

20th fret is at 13.70" so I will round it to 14" total length from nut to end of neck, to allow for some space after the last fret.

2. My understanding is that the 16th fret is where the neck meets the body, which is at 12.063", so the neck pocket length will be 14"-"12.063 for roughly 2".

16

12.063"

0.472" (15-16)

3. For the nut width, I want same string spacing as on regular tele, so I will just measure the distance between A and B strings on a standard tele nut and give it some additional space at the top and bottom strings. This will give me the neck width at the nut.

4. I have a 4 string bridge, but I'm not sure how to determine the neck pocket width and taper, given the scale, neck width at nut, and bridge width between 1st and 4th saddle.

Should I just draw it precisely to scale, or is there a better approach?

If I go to the draw-to-scale approach, and use the drawing to cut the neck, how do I cut the neck pocket to match the neck heel?

5. What length truss rod should I use for 20" scale?

6. Should I aim for 1" neck + fretboard thickness, like on regular guitar?

Any comments on my plan above will be highly appreciated.


Thanks for your help!

Peter

 

[Freeman Keller]

You have pretty much nailed it. A couple of comments, however. I've never worked on a tenor electric but I've had a couple of acoustic tenors on my bench. I think they typically have slightly longer scale than 20 inches, but 20 should work. I also know that there are a variety of tenor guitar tunings, but the ones I have seen were tuned in fifths to CGDA. Just make sure you can buy the string gauges you want to give reasonable tension with whatever scale and tuning you have selected.

There is nothing sacred about the body joint at the 16th fret, that is common on electrics but it can range from 14 t 18. A tele neck pocket is 3-1/8 deep, yours might be a little short. Going to 21 frets or extending the tenon farther into the body (as is done on many set neck guitars) might be a good idea, I really don't know.

Laying out neck width is always a bit funky because we use different measuring criteria at different points. Its honestly just best to lay it out and measure, but you can calculate using geometry. Your spacing at the bridge and nut are fixed. Choose an offset from the edge that you like - its frequently between 0.100 and 0.125, and most of the time is the same down the fretboard. That will determine the overall width at the nut and at the neck to body joint. Most of the time the heel is tapered following that line.

The other minor issue with neck width will be making sure your four pole pickups are the correct spacing for where they will sit on the body of the guitar. You can confirm that on your neck layout.

Truss rod depends a bit on where and how you will do the adjuster and what kind of rod you will use. LMII sells a 12 inch double acting rod (12-3/8 with the adjuster) - I would lay that out on your drawing and see how it looks. If you need a custom length Bitterroot makes them.

Fender's one inch thick heel was selected for ease of manufacture and because it fits nicely in the 1-3/4 thick body. The height of your bridge may affect the overall geometry, you should lay that out along with your neck.

Sounds like an interesting project and I'll be watching as you build it. I think you are doing all the right things with your design.

 

[Peegoo]

^^^All really good advice as usual.

@newuser1

The only thing I'll suggest is to make the instrument a neck-through. There are two reasons for this.

1. It's a custom instrument; you're not building to any existing conventions so there's no need for modularity and interchangeability with other parts.

2. It will make the build stronger with fewer parts necessary. Since it's a solidbody it will be simple because there's no neck angle necessary.

One other consideration for the neck heel width is to select the bridge you're going to use before you lay out and cut the neck/fingerboard to final shape because the bridge string spacing generally dictates the neck width at the heel.

This is an interesting build. If you decide to proceed with the screw-on neck, do some homework on Fender's run of electric mandolins from years back (http://www.guitarhq.com/mando.html). Please keep us posted!

 

[newuser1]

Thanks for the feedback guys!

I agree that the 2" pocket is kind of on the short end, so I'll aim for 2.5", by just moving the neck/body meeting point at 15th fret.

The Fender mando link is great, that's what I'm aiming for but with nicer body shape, probably scaled-down tele .

Let's assume I have the neck shape drawn - how do I get the neck pocket routed? Do I just draw the neck pocket on piece of MDF and carefully cut it out and shape the rounded back and corners by hand, so I can then use it as template to route the actual cavity?

 

[Freeman Keller]

Let's assume I have the neck shape drawn - how do I get the neck pocket routed? Do I just draw the neck pocket on piece of MDF and carefully cut it out and shape the rounded back and corners by hand, so I can then use it as template to route the actual cavity?

That is basically what I do - make a copy of your neck plans and double stick tape it to a piece of mdf or plywood. Drill the corners to a radius that you can handle with your router bit (often 1/2 inch), cut the rest of it to the line and carefully sand. I use the same template to build both the neck and body so I know they will match.

This is a little hard to tell, but the first picture is the neck heel in the mdf template sitting on top of the guitar. The template is screwed to the guitar into areas that will be routed out later (pickup cavities). I'm lining the neck and template up with the centerline of the guitar. In the second picture the neck has been removed and the pocket is being routed.

The sides of your template should have a very slight taper following the sides of the neck heel. You should not be able to slide the neck into it from the end but rather drop it down from the top.

That piece of mdf has both my tele route on one end and a gibson style tenon on the other. Less things to get lost

 

[newuser1]

I measured a standard tele nut between A and B strings and it is exactly 20 mm. I'm using 2.5 mm overhang from both end strings, which makes the neck width at the nut 25 mm.

These commercially produced tenor guitars have nut width of 1-5/16" which is 33.3 mm, much wider than my 25mm.

Tenorcaster

Introducing... the Tenorcaster! We've had a lot of requests for new Tenor models to add to your collection and this one was the obvious next step: a tele-shaped tenor! This mighty little tenor has a 23″ scale that works well with standard tenor tuning (CGDA) and also octave mandolin tuning...

eastwoodguitars.com

Warren Ellis Signature Tenor

After 12 months of collaboration between Eastwood Guitars and multi-instrumentalist Warren Ellis (The Dirty Three, Nick Cave and the Bad Seeds, Grinderman) the new Eastwood Tenor Guitar here. This is the fourth in a series of uniquely new stringed instruments from Eastwood Guitars which include...

eastwoodguitars.com

My bridge width from first to last saddle center is 32 mm, which is less than the nut width of the Eastwood guitar linked above.

Would my neck be too narrow with 25 mm width at the nut and 32 mm width between the centers of the end saddle at the bridge?

If I make it wider at the nut, then I'll have to use a different bridge (modified standard 6 string bridge), which is a pain.

Here is my plan for the neck, for which I used this excellent website:

ekips.org - FretFind2D

FretFind2d models fretboards as a system of line segments on a two dimensional plane to design freboards with multiple scale lenghts and microtonal scales.

www.ekips.org

 

[Freeman Keller]

As I said, my exposure to tenor guitars is limited to a few acoustics that have crossed my workbench. There is a local guy who is quite in to tenors and I've worked on a couple of his. I do not remember the nut widths but the necks seemed awfully narrow to me. Remember that these critters were popular in the 1930's by tenor banjo players looking for a different sound. I did find an add for this lovely old Martin, which lists the scale length as 23 inches and the nut width as 1-1/4 inch or 32mm.

C. F. Martin 0-18T Flat Top Tenor Guitar (1964) | RetroFret

RetroFret Vintage Guitars

www.retrofret.com

There is a set of plans for a 0-18 Martin tenor at MIMF. You would need to sign up to order it but it might give you some background at least

If I use your method of scaling a telecaster, the bottom four strings on my tele are spaced at 0.850 centers. If I add an 1/8 on each side for setback I get 1.100 inches, about 28mm,

So I don't really have an answer. I guess since I happen to like wide nuts on my guitars I would err on the wider side and do a lot more research.

 

[newuser1]

I printed the neck layout and this thing looks tiny; I don't think I would be able to play that. On top of that the shortest truss rod I have is 16", which of course won't work on a 20" scale. I guess it's back to the drawing board, probably going with 22" scale and 32-35 mm nut width. I'll have to figure out what to do with the bridge, possibly using a 4-string bass bridge? Oh well...

 

[newuser1]

I had some time today and routed the truss rod channel and cut the neck outline on the bandsaw. I went with 23" scale and 22 frets because the shortest truss rod I have is 16". I have 2 cutouts from Padauk and Purple Heart, which are wide and long enough for the fretboard. Which one do you guys like better?

 

[newuser1]

I've just realized that I need an extra small neck plate for my tiny neck. Where can I get smaller size neck plates and are there any other alternatives?

 

[crazydave911]

I've just realized that I need an extra small neck plate for my tiny neck. Where can I get smaller size neck plates and are there any other alternatives?

Username "Bezdez" on eBay

 

[fenderchamp]

I've just realized that I need an extra small neck plate for my tiny neck. Where can I get smaller size neck plates and are there any other alternatives?

don't some guitars neck use grommets instead of a neck plate.

https://www.stewmac.com/parts-and-h...75x1Hy2V2LGf75pzb9S8URHK5TUMHHJhoC-ykQAvD_BwE

 

[10orgtr]

I'm a little late to the party, but my Harmony tenor has a 22-5/8" scale, 1-1/4" nut width, 5/16" string spacing at the nut and 7/16" spacing at the bridge. Good luck with your project.
Cheers,
Woody

 

[newuser1]

Some progress with the body today.

 

[eallen]

Looking good!

 

[newuser1]

I actually finished the guitar some time ago and here are some pics.

 

[Freeman Keller]

Looks interesting (and good), how do you like playing it? How does it sound?

 

[newuser1]

Looks interesting (and good), how do you like playing it? How does it sound?

Thanks Freeman!

It's sounds quite nice acoustically as the body is cedar. I made the neck a bit too narrow so I have to be carefull not to slip top and bottom strings off the fretboard, but other than that it's very playable. Unlike other tenor guitar I strung it from A to B, however I'm experimenting with different tunnings and it's great for that.

 

[crazydave911]

Thanks Freeman!

It's sounds quite nice acoustically as the body is cedar. I made the neck a bit too narrow so I have to be carefull not to slip top and bottom strings off the fretboard, but other than that it's very playable. Unlike other tenor guitar I strung it from A to B, however I'm experimenting with different tunnings and it's great for that.

I could have predicted the too narrow neck, most common mistake people make with a tenor. I made my first a little wide but since it's an 8 string it came out fine. One thing Fender at least once knew is with the Musicmaster which was 22.5" scale that a wide neck with a short scale is infinitely more playable. I've used mini Strat necks before because they're too narrow for guitar (for me) but they make a good tenor neck