Bridge height, anyone?

Replies to This Discussion

Permalink Reply by Mortimer Snerd on August 26, 2009 at 3:12am

Nobody here talks much about neck angles, it is ignored because of the "home made" idea of slapping things together. Neck angles play a very important part for high brigdges. Check this link out.
http://www.tundraman.com/Guitars/NeckAngle/NeckAngle.JPG

Permalink Reply by Wichita Sam on August 26, 2009 at 7:15am

Tres,

Bridge height is a function of: 1) initial height of fretboard where it joins the box , 2) neck angle , 3) nut height and 4) desired action. Increase any of these and the bridge height required increases..... Although many/most use neck thru construction, don't assume a "0" degree neck angle. I have seen badly warped necks that mimiced 3-4 degrees neck angle... The more sophositicated the build (I'm thinking about bolt on necks such as reso's) you have to consider neck angle. A 3/4 high bridge on a neck thru design would probably be useless, unless you would intentionally building a Dobro... lol....

The issue of bridge placement is really a function of sound production (volume and quality) Toward the middle of the box will get the most volume accoustically and will get a more "banjo-y" sound. Up to 3/4 toward the tail will reduce the volume a little, but will get a more guitarish sound. Beyond that (I've seen CBGs with the bridge on the tailpiece, not even on the box) you start to loose a lot of volume. Now, if you're amping it, not problem, you just treat it like a solid body guitar and go on. But if you want a "guitar sounding" CBG and want decent volume, I would suggest staying between 2.3s and 3.4 of the way toward the tail end of the box.

hope that helps...

the best,

Wichita Sam

Permalink Reply by Wichita Sam on August 26, 2009 at 7:18am

morning Mort,

The reason few talk about neck angles here is that most are building with neck thru and that assumes a "0" degree neck angle. That being said, a lot of builders make their bread and butter building some form of "bolt on" neck which assumes that they are considering neck angle. They're not talking about it 'cus no ones asking.

Thanks for the link,
the best,

Wichita Sam

Mortimer Snerd said:

Nobody here talks much about neck angles, it is ignored because of the "home made" idea of slapping things together. Neck angles play a very important part for high brigdges. Check this link out.
http://www.tundraman.com/Guitars/NeckAngle/NeckAngle.JPG

Permalink Reply by Mortimer Snerd on August 26, 2009 at 9:16am

"They're not talking about it 'cus no ones asking"
Sam, no one starting out here knows anything about guitar building. Thats another site altogether. A through neck can be shaved down on the top side inside the box to tip the neck downward. This will give him what he wants.
[IMG]http://i95.photobucket.com/albums/l133/1eyecrooked/neckthrough.jpg[/IMG]

Permalink Reply by Tres Seaver on August 26, 2009 at 10:02am

Wichita Sam said:

Tres,

Bridge height is a function of: 1) initial height of fretboard where it joins the box , 2) neck angle , 3) nut height and 4) desired action. Increase any of these and the bridge height required increases..... Although many/most use neck thru construction, don't assume a "0" degree neck angle. I have seen badly warped necks that mimiced 3-4 degrees neck angle... The more sophositicated the build (I'm thinking about bolt on necks such as reso's) you have to consider neck angle. A 3/4 high bridge on a neck thru design would probably be useless, unless you would intentionally building a Dobro... lol....

Yep, that is what I have been thinking. I wonder if lowering the notch in the "top" of the box to get neck angle is a resonable choice. I realize that I would need to shim the fingerboard somehow to get it back flush with the top.

Wichita Sam said:

The issue of bridge placement is really a function of sound production (volume and quality) Toward the middle of the box will get the most volume accoustically and will get a more "banjo-y" sound. Up to 3/4 toward the tail will reduce the volume a little, but will get a more guitarish sound. Beyond that (I've seen CBGs with the bridge on the tailpiece, not even on the box) you start to loose a lot of volume. Now, if you're amping it, not problem, you just treat it like a solid body guitar and go on. But if you want a "guitar sounding" CBG and want decent volume, I would suggest staying between 2.3s and 3.4 of the way toward the tail end of the box.

hope that helps...

Thanks very much. That is just the kind of information I was looking for.

Permalink Reply by Tres Seaver on August 26, 2009 at 10:05am

Mortimer Snerd said:

Nobody here talks much about neck angles, it is ignored because of the "home made" idea of slapping things together. Neck angles play a very important part for high brigdges. Check this link out.
http://www.tundraman.com/Guitars/NeckAngle/NeckAngle.JPG

Thanks for that image and the one before. I hadn't thought of shaping the neck inside the box, although I did contemplate lowering where it came out at the top.

Permalink Reply by Wichita Sam on August 26, 2009 at 7:12pm

"A through neck can be shaved down"..... Mortimer,

Of course it can be done, but I would guess that less than 1 % of all neck thru construction is intentionally anything other than 0% neck angle. I was talking about how it's normally done. The great majority of CBGs with neck angles are bolt on designs. By the way, your pic suggests a fairly elegant solution to achieve neck angle on a neck thru design... mIght be extremely useful on CBFiddles......

thanks,
the best,

Sam


Mortimer Snerd said:

"They're not talking about it 'cus no ones asking"
Sam, no one starting out here knows anything about guitar building. Thats another site altogether. A through neck can be shaved down on the top side inside the box to tip the neck downward. This will give him what he wants.
[IMG]http://i95.photobucket.com/albums/l133/1eyecrooked/neckthrough.jpg[/IMG]

Permalink Reply by Mark Werner on August 26, 2009 at 8:38pm

I did a lot of research on neck angle before I started building my mandola; most all the references said 5% for an instrument of this type. I really took pains measuring and really sweated making that cut!

Worked well, though; I ended up with a bridge height of about 3/4" and a nice, loud, ringing instrument.

Permalink Reply by Tres Seaver on August 26, 2009 at 10:00pm

Mark Werner said:

I did a lot of research on neck angle before I started building my mandola; most all the references said 5% for an instrument of this type. I really took pains measuring and really sweated making that cut!
Worked well, though; I ended up with a bridge height of about 3/4" and a nice, loud, ringing instrument.

Thanks for the feedback. I've done a little calculating myself (see if I can get this to work in this silly editor):

Neck Angles
	Inches	1/32 inch
Scale Length	24.5	784
Box Length	9	288
Bridge from Top	6.5	208
Fingerboard Length	18	576
Neck Depth	0.75	24
Fingerboard Depth	0.25	8
Bridge Height	0.75	24
Nut Height	0.13	4
		Height	at bridge			Extra Action
Angle (degrees)	Tail Thinning	Neck	Fingerboard	Relief @ nut	@ bridge	@ FB tip	@ octave
0	0	0	8	0	12	8.82	6
0.5	2.51	1.82	9.82	5.03	10.18	7.48	5.09
1	5.03	3.63	11.63	10.05	8.37	6.15	4.18
1.5	7.54	5.44	13.44	15.08	6.56	4.82	3.28
2	10.06	7.26	15.26	20.1	4.74	3.48	2.37
2.5	12.57	9.07	17.07	25.12	2.93	2.15	1.46
Columns (all lengths in 1/32”)
Tail thinning	How much thinner will the neck be at the “bottom” of the box?
Neck @ bridge	How high would the “notional” neck be if extended the bridge?
FB @ bridge	How high would the “notional” fingerboard be if extended to the bridge?
Relief @ nut	How much relief is generated at the nut?
Action @ bridge	How much extra action is present at the bridge?
Action @ FB tip	How much extra action is present at the top of the box / end of the fingerboard?
Action @ octave	How much extra action is present at the octave point?

So, with one degree of neck angle, it looks as though I trade away 5/32" of the tailpiece in exchange for getting the extra action at the octave down to just over 1/8", which seems OK for my playing style. Your 5% looks to be closer to 3% (if my trig is right), which would have about half a 1/32" extra action at the octave (for my scale, fretboard, etc.) I would have to thin off 15/32" of the tailpiece to get there, which is too much for the load bearing bit: I'd be left with just over a 1/4" to anchor the strings.

Permalink Reply by Tres Seaver on August 26, 2009 at 10:05pm

Tres Seaver said:

Thanks for the feedback. I've done a little calculating myself...

I'm attaching the spreadsheet I used to do this noodling, in case it would be helpful to anybody else (or somebody wants to tell me what a bonehead I am :)

Attachments:

• neck_angle.xls, 111 KB

Permalink Reply by Tres Seaver on September 1, 2009 at 12:50pm

I went ahead and tried the "angled slot under the top" method Mortimer suggested, and do have something between a half a degree and a degree of relief on the neck. Between that and a fretboard, I think the action is going to be low enough to fret at the end of the fretboard.

Now if only I had done a better job fretting it. ;(

Pictures up tonight.