StewMac tools

7 string specs

Please put your pickup/wiring discussions in the Electronics section; and put discussions about repair issues, including fixing errors in new instruments, in the Repairs section.

7 string specs

Postby John Morton » Tue May 02, 2017 8:52 pm

I plan to build a 7 string guitar this year. I would be interested to know if string spacing and fingerboard radius specs are generally the same as for 6 strings.
thanks
John Morton
 
Posts: 5
Joined: Tue May 02, 2017 11:19 am

Re: 7 string specs

Postby Gordon Bellerose » Wed May 03, 2017 6:37 pm

I have the specs from a Carvin 7 string at home.
It will be a couple of days before I can get them to you.
I need your help. I can't possibly make all the mistakes myself!
Gordon Bellerose
 
Posts: 926
Joined: Wed May 30, 2012 11:47 pm
Location: Edmonton AB. Canada

Re: 7 string specs

Postby Gordon Bellerose » Thu May 04, 2017 11:51 pm

OK. These are the measurements I took from a Carvin 7 string that came into the shop for a set up.
I thought that while I had it in my hands, I would measure it in case I ever wanted to build one.
This guitar is a 27 inch scale, so if you are building a shorter scale some of the measurements will have to be adjusted slightly.
Also, if you are thinking of building a 7 string, or any guitar, you should have your bridge in hand when you do your full sized plan drawing.
Bridge width, scale length, and nut width, are all factors in how wide the base of the neck must be.
Bridge height, neck thickness, finger board thickness, and fret height are all determining factors for neck pocket angle, if any.

Nut width = 1+29/32
Neck width at base = 2+19/32
Neck thickness at 1st fret = 25/32 or .780
Neck thickness at 12th fret = 27/32 or .847
I need your help. I can't possibly make all the mistakes myself!
Gordon Bellerose
 
Posts: 926
Joined: Wed May 30, 2012 11:47 pm
Location: Edmonton AB. Canada

Re: 7 string specs

Postby Gordon Bellerose » Fri May 05, 2017 9:31 am

I should add that the fret board radius on this guitar was 16 inch.
I need your help. I can't possibly make all the mistakes myself!
Gordon Bellerose
 
Posts: 926
Joined: Wed May 30, 2012 11:47 pm
Location: Edmonton AB. Canada

Re: 7 string specs

Postby John Morton » Fri May 05, 2017 1:53 pm

Thanks Gordon. This is interesting. 27" is an extraordinary scale for steel strings, more like for a nylon classical. But the 16" radius is pretty tight for that wide fingerboard.

This project is for a Brazilian player whose usual 7 string has a flat fingerboard and wide string spacing (though not as wide as classical, I think). I should mention that this will be a steel resonator instrument, which unfortunately doesn't work at all with nylon. The player is highly accomplished and very interested in my work, so I am looking for a compromise that will tempt him to adopt to a flatpick while preserving qualities that matter to him.
John Morton
 
Posts: 5
Joined: Tue May 02, 2017 11:19 am

Re: 7 string specs

Postby Freeman Keller » Fri May 05, 2017 9:43 pm

John Morton wrote:... I should mention that this will be a steel resonator instrument, which unfortunately doesn't work at all with nylon. The player is highly accomplished and very interested in my work, so I am looking for a compromise that will tempt him to adopt to a flatpick while preserving qualities that matter to him....


That got my attention. I'm a big resonator fan (however just six strings and pretty normal scale lengths) - I'll be interested in seeing what you decide to build.
Freeman Keller
 
Posts: 224
Joined: Mon Feb 27, 2012 11:34 am

Re: 7 string specs

Postby John Morton » Fri May 05, 2017 10:48 pm

Freeman Keller wrote:
John Morton wrote:... I should mention that this will be a steel resonator instrument, which unfortunately doesn't work at all with nylon. The player is highly accomplished and very interested in my work, so I am looking for a compromise that will tempt him to adopt to a flatpick while preserving qualities that matter to him....


That got my attention. I'm a big resonator fan (however just six strings and pretty normal scale lengths) - I'll be interested in seeing what you decide to build.


I had a crack at this a couple years ago, and made a 7 string that turned out to be a little off the mark. It was brass, because my guy was captivated by the beauty of the sound. But I think he started to want the decay and separation you get when there is less sustain. So this time it's stainless steel, and I won't defer to his customary flat and wide fingerboard. Maybe a 20" radius, and narrower like I would do for a flatpick player. Steel strings are a must, and since those eat up his fingernails he will simply have to use a flatpick. I trust that it will sound so good and so different that he will learn what he has to, to play it.

here is the brass one:
Attachments
7 string2.jpg
John Morton
 
Posts: 5
Joined: Tue May 02, 2017 11:19 am

Re: 7 string specs

Postby Freeman Keller » Sat May 06, 2017 11:26 am

Nice, John. A few years back I was thinking of building a metal resonator and because I worked in a fab shop and one of my friends is among the best titanium welders in the world (he worked at Moots cycles building ti framed bikes) I was planning to make it out of ti (would that be a TiCone?). Anyway, for various reasons the metal turned to wood and I built this one

Image

Since I play mostly fingerstyle blues and lots of slide I prefer a wide flat fretboard - 20 inch radius is about ideal.

Please pictures of yours, including if you would like to share, some of the construction and internal details.
Freeman Keller
 
Posts: 224
Joined: Mon Feb 27, 2012 11:34 am

Re: 7 string specs

Postby Clay Schaeffer » Sat May 06, 2017 6:00 pm

Don't some players use finger picks and thumb picks on those things?
Clay Schaeffer
 
Posts: 1039
Joined: Fri Jan 06, 2012 12:04 pm

Re: 7 string specs

Postby Freeman Keller » Sat May 06, 2017 7:33 pm

Clay Schaeffer wrote:Don't some players use finger picks and thumb picks on those things?


I own three different resonators, a spider, a biscuit and this tri. I play all of them fingerstyle, use finger and thumb picks when I want more bite, flesh and nails for a little mellower sound. The wooden tricone is interesting - played with picks its got that reso bark, played with fingers its almost acoustic sounding.
Freeman Keller
 
Posts: 224
Joined: Mon Feb 27, 2012 11:34 am

Re: 7 string specs

Postby John Morton » Sun May 07, 2017 11:53 am

That wood tricone is nice, Freeman. I was shown a similar prototype maybe 15 yrs. ago at National's shop, and thought it sounded better than anything they made. I wouldn't know where to begin with photos, but there's a gallery here if you're interested: http://www.jmorton.us/

Internal details: I just copied what I saw inside some early Nationals that I took apart to repair in 1992: soft soldered seams, banjo-style neck stick (except on the ukuleles), spun cones and cone tray (on the singles). I have made maybe 6 different cone sizes and styles, according to the requirements of the different designs.

Titanium: I got to know an Irish panel beater in Oakland who does coachwork for antique and original race cars. His stuff is miles beyond anything I could ever do. But he did like the guitars, and asked me how he should design a resophonic violin for his niece. I discouraged him from the reso scheme, but he wound up making a perfect violin body, TIG welded from .020" titanium. He said it had to be Ti so it would weigh the same as a wood violin!
John Morton
 
Posts: 5
Joined: Tue May 02, 2017 11:19 am


Return to Flat-Top Acoustic Guitars and Bass Guitars

Who is online

Users browsing this forum: No registered users and 3 guests

Your purchase from these sites helps support the MIMForum, but only if you start at the links below!!!
Amazon music     Amazon books     Amazon tools     Rockler tools     Office Depot    

The MIMF is a member-supported forum, please consider supporting us with a donation, thanks!
 • Book store • Tool store • Links •