6-string questions

finkdaddy

finkdaddy

Well-known member
Joined
Jan 8, 2011
Messages
411
Reaction score
0
Location
Waterford, WI
I have a customer who is asking for a 6-string tenor. She wants the
1st and 3rd strings doubled.

Is there anything that I need to consider in my build?
I've never built one before, so I don't know if you should widen the width of the fretboard, nut, and saddle?

Is there anything I should do in designing the top to compensate for the extra string tension, or is it not enough to worry about?

Also, what are the guidelines on string spacing for a 6 or 8 string uke?

Any advice would be greatly appreciated.
Thank you!

~Fred
 
Approximately 20 pounds of extra string tension is certainly enough to worry about so make sure you modify your bracing and/or soundboard thickness.
When I've built 6 string ukes I've used a 1 1/2" nut width and spaced the paired strings 2mm apart from each other.
 
Moore Bettah Ukuleles said:
Approximately 20 pounds of extra string tension is certainly enough to worry about so make sure you modify your bracing and/or soundboard thickness.
When I've built 6 string ukes I've used a 1 1/2" nut width and spaced the paired strings 2mm apart from each other.
Click to expand...

Thank you, Chuck, that is very helpful!
 
Oh my.
I've now been informed that she wants a long scale, 6 string tenor.
I understand that the two extra strings will add some tension, so I will beef up the sound board and probably the bridge patch as well to support the new strings.

But can anyone give me advice on pushing the neck out an extra 2 or 3 frets?
If I'm thinking of this correctly, I can't actually make the distance between the nut and saddle any longer, so I would have to change where the neck attatches to the body, right? But then would I have to change where the sound hole is? And then would I have enough room at the front of the body for attatching the neck?

I know I sound silly, but I just can't wrap my brain around the geometry. :eek:

Here is a video, just for reference: https://www.youtube.com/watch?v=Z-YwV1Vek94#t=56

Thank you, everyone!

~Fred
 
I would draw up a plan of what I want to produce, getting all the dimensions right. Then measure the final nut-saddle distance and use a fret calculator such as that provided by StewMac to give the positions for cutting the frets. Remember to include the compensation bit.
 
There are two possible scenarios going on here as far as I can determine from your description.

A long scale tenor means that you are talking about a scale length longer than the standard 17". That's not a problem as long as you are able to cut a fret board to that scale length.

The other is just that they want a 17" scale length but have the neck/body join at a higher fret than what you are using. Commonly at the 14th instead of the 12th.

With the long scale option, you are able to keep the bridge in a similar spot on the sound board to your usual build, and the extra length of the scale pushes the nut further from the body. Giving you an opportunity to join the neck to at a higher fret. Say 14 instead of 12.

The other option where you keep the same scale length but move the neck to body join from say the 12 to 14th means that the saddle has to move towards the sound hole by the distance of those 2 frets.

Now it depends on you body shape if this is an acceptable option. On my instruments I have very little leeway to do this. Mine are designed to have a 12th to body join, so if the client wants longer then I need to increase the scale length in order to keep that bridge in the spot I've designed it for.

My advice is that you get a big piece of paper out and start sketching in actual size the relationships so you don't get a nasty surprise 1/2 way through the build.

I do this regularly on custom builds where clients want something out of the norm. Far too easy to get confused on a dimension when you are use to doing something one way but have to deviate from the norm.
 
Thanks guys.

She wants a longer scale so that more frets are exposed above the body. I usually make mine join at the 14th fret, but from the examples she showed me, she want's it to join at the 16th fret. I don't want to have to move the bridge though, so I will just recalculate the new scale length.
I'm assuming I'll have to build this one pretty hefty to accomodate for the longer neck and the extra two strings.

Thanks again for the advice. I don't know why that question threw me off so much! :eek:

~Fred
 
Great advice, Allen. Get the client to sign the drawing, too. Nothing worse than to hear, "That's not what I wanted and I'm not paying!"
 
I have a custom 6-string tenor myself, and the luthier asked me if I wanted to make it a "super tenor" and use a baritone-length neck on it, but I wanted it to fit in a regular Tenor case so I just got a standard Tenor neck, and it joins the body at the 14th fret.liliu3.jpg
 
Pueo said:
I have a custom 6-string tenor myself, and the luthier asked me if I wanted to make it a "super tenor" and use a baritone-length neck on it, but I wanted it to fit in a regular Tenor case so I just got a standard Tenor neck, and it joins the body at the 14th fret.View attachment 63796
Click to expand...

That's it exactly!
 
Aloha finkdaddy,
One possible resource you might want to take a look at is David Hurd’s book. Here is a link to google books http://books.google.com/books?id=l5uInDconwAC&pg=PA6&lpg=PA6&dq=string+tension+vs+lower+bout+area&source=bl&ots=SkdxN7FUK8&sig=jx7bCgb_b8SJ9oTTYMxyejELBPQ&hl=en&sa=X&ei=sn39UpDJH5HhoASIoIGgDA&ved=0CCQQ6AEwAA#v=onepage&q=string%20tension%20vs%20lower%20bout%20area&f=false

On page 5 he discusses String tension and gives the formula: T = 4 * L*L * F*F * m (where L = scale length, F = frequency of the individual string and m = mass). He also has a visual (figure 1) where he shows the relationship between total string pull vs. lower bout area. The graph should suggest that the proposed design (longer scale length and 2 additional strings) will increase the tension considerably. You would have to do the math to confirm, but I would not be surprised if the longer scale length and 6 total strings takes you into the realm of the 8 string tenor (with a 17” scale length). Slide your eyes across and to the right of figure 1 and you will see that an 8 string tenor and guitar have nearly the same amount of string tension but a Tenor body has a much smaller area to distribute that force. As everyone else suggested you will have to brace accordingly.

The proposed design is probably close to having guitar string tension on a tenor sized body. David would use a “Bridge Doctor” on his 6 and 8 string designs and it might be worth looking into. The customer proposed design seems to be pushing the limits of the tenor sized body. I am not suggesting you do not try it or that it is not possible but just realize the boundaries are being pushed to the extreme. Make sure you and the client are clear on any potential warranty issues (ie: bellying in front of the bridge). Search the forum, there are threads discussing warranty issues involving “longer scale” instruments. Both buyer and builder should be aware of the physics involved. Hope that helped.
 
Last edited:
Kōāpa‘a;1477915 said:
Aloha finkdaddy,
One possible resource you might want to take a look at is David Hurd’s book. Here is a link to google books http://books.google.com/books?id=l5uInDconwAC&pg=PA6&lpg=PA6&dq=string+tension+vs+lower+bout+area&source=bl&ots=SkdxN7FUK8&sig=jx7bCgb_b8SJ9oTTYMxyejELBPQ&hl=en&sa=X&ei=sn39UpDJH5HhoASIoIGgDA&ved=0CCQQ6AEwAA#v=onepage&q=string%20tension%20vs%20lower%20bout%20area&f=false

On page 5 he discusses String tension and gives the formula: T = 4 * L*L * F*F * m (where L = scale length, F = frequency of the individual string and m = mass). He also has a visual (figure 1) where he shows the relationship between total string pull vs. lower bout area. The graph should suggest that the proposed design (longer scale length and 2 additional strings) will increase the tension considerably. You would have to do the math to confirm, but I would not be surprised if the longer scale length and 6 total strings takes you into the realm of the 8 string tenor (with a 17” scale length). Slide your eyes across and to the right of figure 1 and you will see that an 8 string tenor and guitar have nearly the same amount of string tension but a Tenor body has a much smaller area to distribute that force. As everyone else suggested you will have to brace accordingly.

The proposed design is probably close to having guitar string tension on a tenor sized body. David would use a “Bridge Doctor” on his 6 and 8 string designs and it might be worth looking into. The customer proposed design seems to be pushing the limits of the tenor sized body. I am not suggesting you do not try it or that it is not possible but just realize the boundaries are being pushed to the extreme. Make sure you and the client are clear on any potential warranty issues (ie: bellying in front of the bridge). Search the forum, there are threads discussing warranty issues involving “longer scale” instruments. Both buyer and builder should be aware of the physics involved. Hope that helped.
Click to expand...

It does help. Thank you very much!
 
You must log in or register to reply here.

Similar threads

S
Strings String questions
Replies
10
Views
382
bbkobabe
bbkobabe
Adomaru
8-String Baritone Owners- strings recommendations and more questions.
Replies
3
Views
434
bbkobabe
bbkobabe
Coast_Ukulele
5-String (or more) questions.
Replies
10
Views
637
Coast_Ukulele
Coast_Ukulele
M
2 String Questions
Replies
4
Views
497
Cadia
Cadia
M
5 string set up questions
Replies
6
Views
380
merlin666
M
Top Bottom