Need some info for setting a uke neck

I got this Koa tenor uke kit for Christmas, and it came with a complelely built body, and separate neck, fretboard, bridge, etc.... It will also need finsh applied when built.

So, the neck and body have a dovetail type joint, but it is not tighgt, and will need wedged. I need pointers for the setting of the neck angle, if that's even necessary, and how to sand the bottom of the neck heel so that it will mate nicely to the body of the uke. Right now, the neck to body mating surface of the neck does not meet flush with the body, as it is a semi-finished neck. The angle of that mating surface seems to be dependent on neck angle.

So the big questions for me are:

1. Is there a neck angle requirement or some geometry I need to ensure to keep the string height at a good measurement? Does the fretboard lie in line with the top of the bridge, or something else that I can go from?

2. How do you ensure that the neck centerline, body centerline, and neck to body squareness is maintained while also keeping the neck angle correct and clamped for gluing.

Just want to attempt getting this thing as right as I possibly can. I don't really have access to large wood shop equipment, just normal tools.

Thanks in advance. Your advice will be appreciated.

It's kind of hard to describe in words but I'll give it a try.

Yes, neck angle is very important. To understand neck angle, I find that drawing it out full scale is the best way.

The height of the strings off the top at the bridge determines the torque on the top and that effects structure and tone so you want to start there and work backward. Seems like most folks are in the .400" neighborhood.

Once you have that number, draw all the elements and figure out the relationships. You need to know top doming, fingerboard thickness, fret height, and preferred action.

First draw a side view of the body with any dome in the top (the back is irrelevant). Then locate the bridge and draw a point .400" (or your chosen string height) above the bridge (point A). Then mark some points above the neck/body joint. One a distance equal to your fingerboard thickness. One above that equal to your fret height. One above that equal to the action you want at that fret (point B). A line from point A to point B represents your strings.

Work backward form there to get a line that represents your fingerboard and you have the critical info. It really helps to make a jig using that info from the drawing that will help you set the neck. I'll see if I can get you a photo of mine. Easier than describing it.

In an ideal world, the plane of the fingerboard will match the plane of the top between the heel and soundhole and you will be good to go. If not, there are several possible fixes but all prioritize keeping the relationship you've established on the drawing.

As for getting the dovetail right, it sounds like you understand the process. Most people "floss" the shoulders of the heel with sandpaper until you you get the neck angle right while keeping your center line. Then shim the joint to make it tight.

Good luck.

You can do it all with a straight edge. Just tape the bridge in place on the body. Hold the neck in place and use a straight edge to check the center line with the body and the neck angle. If your fingerboard and frets are on the neck....you can see how high or low the saddle will be to get reasonable string action. If its just the neck with no fingerboard...just do the same thing but adjust for the missing thickness.
Usually the neck angle is around 1.5 degrees so the angle the top makes with the sides at the neck joint should be 91.5 degrees to get a good fit with the fingerboard extension. Neck angle is more important than a good fingerboard extension joint to play well. If you find your fingerboard floats up above the top you can shim it to keep the angle

Here's what I do:

1. Dry clamp the neck to the body
2. mark the saddle location on the soundboard and, using double stick scotch tape, afix the bridge and saddle at that location
3. Place the fretted fret board on the neck if you haven't already done so
4. Make a faux nut just a hair taller than the frets and put it in place
5. With the uke on its back, place a 1/8" drill bit at the 14th fret
6. Place a straightedge with one end on the faux nut and the middle resting on the drill bit at the 14th fret
7. The bottom of the straightedge should just touch the top of the saddle. If it is too high or low, you need to adjust the neck angle until it touches the top of the saddle.

Hope this helps.

First thing..how high is the bridge and how high do you want the saddle to be ?..I've seen some ukes with a half inch of saddle sticking up.....it looks daft to me on a uke

Timbuck said:

First thing..how high is the bridge and how high do you want the saddle to be ?..I've seen some ukes with a half inch of saddle sticking up.....it looks daft to me on a uke

Click to expand...

An overly tall saddle not only looks daft but it's unhealthy for the uke. As Kent mentioned, height of the strings at the bridge area is my most important figure. Everything is set up around that. Keep in mind that the bridge may lift a tiny bit under string pressure so that needs to be considered as well.

Here's the kind of jig I use. The straight edge represents the string.

A) The spacer here is the string height at the saddle.

B) Spacer here is the height of the action at the 12th fret.

C) Spacer here is a tad taller than a fret.

When all of these touch, the neck set is good.

WOW! Thanks for all the quick replies.

I do have a couple questions as follows:

Kent, I'm having a bit of trouble with this statement:

"In an ideal world, the plane of the fingerboard will match the plane of the top between the heel and soundhole and you will be good to go."

I am not sure what that means. Sounds like the fingerboard is parallel to the top, but I don't know, are you talking about the heel of the neck? Newbie, so excuse me, please!

And Ksquine, it sounds as if the body is correctly made, and the fretboard extension goes flush to the uke's top, then you should be close to the 1.5 degrees. Is that making sense? Seems like a tweak may be necessary.

One final question. How do you get the base of the neck to have a good fit with the body? You know, have it meet the body squarely with no gaps, etc. Now this is a kit, so to speak, and so a lot of the difficult work is done. The body is finished, and has a dovetail in it. The neck is a bit more done than rough cut, and the fretboard is done, actually, pretty well. But the fit of the neck to the body needs work for a nice fit.

Thanks. The explanations are very good and helpful.

jsrfo said:

"In an ideal world, the plane of the fingerboard will match the plane of the top between the heel and soundhole and you will be good to go."

I am not sure what that means. Sounds like the fingerboard is parallel to the top, but I don't know, are you talking about the heel of the neck? Newbie, so excuse me, please!

Click to expand...

I think if you draw it, it will make more sense but I'll give it a shot. If you follow the directions above, you will establish the plane that the fretboard should be in. Given the geometry that already exits on your body, the fretboard plane may or may not be parallel to the plane of the top. If it's not and you try to attach the neck and glue the fretboard extension to the top, you will end up with a fretboard that is no longer flat. It may slope upward or downward once it attaches to the body. There are a few different ways to fix that depending on which way it's off and by how much. You can shim the fretboard extension, you can taper the extension, you may even be able to sand the top. Or if your fretboard does not yet have frets in it, you can attach it with small kink and just sand/plane the top flat again. Or some combo of the above.

Getting all of that perfect is no small feat and it's always a source of frustration for new builders. Best thing is to get a grasp of the geometry you're trying to achieve and go at it slow.

I'd like to chip in regarding the heel - body joint. It's much easier to get a tight fit if you hollow out the face of the heel before you start sanding what's left. That gives you a rim to work with, and much as an upside down bowl is steady on a sanding plate (or whatever) the neck won't rock from side to side, creating a hump in the middle of the area.

Let's see if I can find a pic. Well one of these shows what I mean.

http://argapa.blogspot.se/search/label/Neck joint

I shape my bodies with a flat area at the heel so it's easy to set the neck and also on some island style models to put a fret at the joint. Others have a radius on the body and there are clever jigs to sand the joint perfect. In any case I think the hollowing out part is a good shortcut.

Wow, is this an incredible forum or what. The sharing of knowledge and talent is amazing.

In my experience, the time to obtain a tight joint between the neck and body is when you first cut the neck blank. The key is sharp tools and good technique, the latter of which comes with experience.

My neck-body joint is a bolted mortise and tenon. I use a table saw with the blade set at a 3 degree angle to make slots on either side of the blank at the 14th fret position, which provides the hollowed profile Sven mentioned above. I then make the tenon with a router template and a very sharp chisel. It is also important that the sides are flat widthwise (no cupping) where the neck meets the body (known in luthier jargon as the heel).