choosing a correct neck angle

[li2ljay]

I'm a rookie builder so please excuse the possibly open ended question . But ....what is the most common method used to determine the neck angle that should be used (on a acoustic ). I know scale length and bridge hieght all play a role in the eqation.... But is there a mathematical eqation used to figure this out . I'm designing a build and I want to get this right , well ...kind of have to if I want it to be a good player . Thanks !

[arie]

Originally Posted by li2ljay

I'm a rookie builder so please excuse the possibly open ended question . But ....what is the most common method used to determine the neck angle that should be used (on a acoustic ). I know scale length and bridge hieght all play a role in the eqation.... But is there a mathematical eqation used to figure this out . I'm designing a build and I want to get this right , well ...kind of have to if I want it to be a good player . Thanks !

use trig. solve for angle A using your scale length and saddle height. scale length is your hyp. and saddle height is your side opp.

this will get you real close. final adjustments are done when fitting the neck in.

i have no idea what is the most common method, but since this method involves math it's a good place to start.

[Sam VanLaningham]

Hi. I'm a novice builder so don't trust me! However, I built a dovetail neck jig following other designs that uses a piece of angle iron on an adjustable surface that the neck is attached to determine the proper angle. Basically the body is set vertically on the top of the jig and the plate with angle iron is rotated to be flush with the top between the neck join to the bridge. Then the angle automatically routes into the neck join. Here's a pic of the one I based mine off of. And also here's a YouTube explaining what I poorly described. Good luck.

https://m.youtube.com/watch?v=qq1ff1-cdrQ


Sam

[li2ljay]

Very nice jig Sam ! I guess I was hoping for an easier method . Not that I don't like it !
As for the math....that's a good start . I'll give that a shot . I appreciate the input .

[Ben-Had]

There are a number of variations you can use. I build my steel string guitars with a 25' radius into the x-braces and tone braces, braces above the sound hole are flat. I use 88.7* for my neck/heel angle and a complimentary angle of 91.3* on the body. I sand my top rim dead flat to begin with which means I then need to sand in the top slope of 1.3* which goes from about the top of the sound hole area to the neck block. This will give a flat line of 180* to get the proper height at the bridge. My bridge thickness is usually around .34" or so. Depending on how accurately you do this there may or may not be some tweaking of the neck set angle at the end.

[Sam VanLaningham]

Originally Posted by li2ljay

Very nice jig Sam ! I guess I was hoping for an easier method . Not that I don't like it !
As for the math....that's a good start . I'll give that a shot . I appreciate the input .

Hah! I used the photo of the jig that inspired mine....not a photo of my jig, which looks half this good but is almost as functional I hope!

The reason I went this route is because I tried to cut my dovetail joints by hand and completely sucked at it. Thus I knew I had to up my jig game....The auto neck angle component was a bonus! Im really glad I did because this thing is super useful. Cool.

Sam

[viento]

@ Sam: excellent jig you´ve made!

Just a little addition:
After I watched the above mentioned video in youtube I bought the plan to build this useful jig for 20$ from www.obrienguitars.com.

[Tom West]

Originally Posted by Ben-Had

There are a number of variations you can use. I build my steel string guitars with a 25' radius into the x-braces and tone braces, braces above the sound hole are flat. I use 88.7* for my neck/heel angle and a complimentary angle of 91.3* on the body. I sand my top rim dead flat to begin with which means I then need to sand in the top slope of 1.3* which goes from about the top of the sound hole area to the neck block. This will give a flat line of 180* to get the proper height at the bridge. My bridge thickness is usually around .34" or so. Depending on how accurately you do this there may or may not be some tweaking of the neck set angle at the end.

This is about the same way I do it. What may not be obvious to a lot of folks dashing out to build a guitar is that the angle is very dependent on the radius of the top and how that is handled. Some newbees build the box not thinking about the neck until the box is completed. By then they are in trouble and need a way to fix the problem. The main concern is to transition from the neck to the top in the same plane for the fingerboard extension and have the correct height of that plane at the bridge position.
Tim has given one solution that works.
Tom

[pops]

I usually lay a straight edge on the body and extend toward the nut, the neck without a fingerboard should be 1/8" below the straight edge up at the nut. This can vary if your fingerboard is extremely thick or thin, but is a good reference and starting point. I also use this when resetting a neck as a reference point.

[tjp]

I use a 28 ft radius on everything, sometimes I leave the middle few inches of the UTB flat. Then I sand/plane an accurate 1.5ish degree angle into the head block. It's usually very close after the radius dish. Note: I center the radius dish just in front of the bridge location.

I use a butt joint neck, which makes the next part easier. I rough it to 1.5 degrees to match the head block, then I tape a 1/8 drill bit to the top at the bridge location. Mock the neck up to the body w/o fingerboard, and fiddle with the angle til a straightedge just touches the drill bit when laid on the neck. Works just about right with a .375 inch bridge.

[li2ljay]

Perfect , I just found a video by blues creek guitars and he uses the same radius , 28 ' and a 1 1/2 ° angle fir the neck . Thanks everyone for the great info .....love this forum !

[tjp]

I just noticed that I used "accurate, 1.5 ish" in a sentence. I kind of like that!

John's videos are a huge help for demystifying this stuff.

Last point - the approach I have recently settled on is to get the angle very close, then modify the bridge height a few thou if necessary. Saves a lot of time and headaches. My last few, the bridge has varied between .350 and .375.

[li2ljay]

That's " perfectish " ...lol
But really , thanks . I'll be using this technique for now !