The Acoustic Guitar Forum

The Acoustic Guitar Forum (https://www.acousticguitarforum.com/forums/index.php)
-   Build and Repair (https://www.acousticguitarforum.com/forums/forumdisplay.php?f=44)
-   -   1973 Sigma DR-7 neck reset (https://www.acousticguitarforum.com/forums/showthread.php?t=563701)

Sperry 11-14-2019 02:49 AM

1973 Sigma DR-7 neck reset
 
Greetings!

Is this neck attached with a mortise tenon joint, with string tension countered with a single lag and nut?

Standard fix is to pull a couple of frets and steam the joint?

I knew I would not get to the project for a couple of years and the guitar required both a complete fret job and neck reset, so I sold it cheap to a guy looking for a decent winter project, along with two far more hopeless instruments. But as always, inquiring minds want to know. :)

Beautiful wood. The headstock overlay was grimy and dusty but not scratched. After removing the tuners, I have a feeling it'll clean up like fine furniture. So flipping the guitar is a feel-good moment. The inside resembled a D-28.

https://avatarhost.files.wordpress.c...-end-block.jpg

ChrisN 11-14-2019 10:10 AM

I had a nut like that on my Conn (from Matsumoku) from the '70s. The joint on mine is a sliding vertical dovetail under a glued-down fretboard. I believe some Sigmas came from the same factory during this period, and yours could well have the same joint. The nut/bolt hold the neck in place during gluing.

I reset mine - here's my thread on that - https://www.acousticguitarforum.com/...d.php?t=484657 In it, there's a link to my photo gallery of the joint from various angles.

I love my Conn, and future resets will be a breeze, as there's no need to re-glue the fretboard with the vertical joint (no fret buzz up high, either, even with 4/64 on E), and I kept my intonation because I didn't shorten the neck with a cut. I did add another bolt/nut (via the insert shown) to the existing bolt/nut just to keep things tight.

Also, I didn't steam it apart - I used a clothes iron (mostly on the fretboard extension) and [CAUTION ALERT] a heat gun. I made a foil-covered cardboard surround so I could keep heat off the wood and binding, but it would be very easy to burn and/or melt guitar parts. It took a lot of time and finesse to do, with lots of pulling/heating/pulling/heating, but I love the result.

Sperry 11-14-2019 11:42 AM

Wow, I've really got to keep an open mind when disassembling these instruments. I could imagine myself prying one way when it is supposed to go the other. The one I pictured is now 40 miles away, but the next one I get might stay for a few years.

Thanks for linking your old post. I'd have thanked you there, but hate being the one to "bring up" an older post. :D

Edgar Poe 11-14-2019 12:45 PM

That is a modification I make to ALL dovetail neck reset I do. I heard all kinds of remarks about how it ruins the tone. If anything in my opinion, it makes for a much more solid neck joint.

Ed

https://previews.dropbox.com/p/thumb...00&size_mode=3

ChrisN 11-14-2019 12:45 PM

Quote:

Originally Posted by Sperry (Post 6211488)
Wow, I've really got to keep an open mind when disassembling these instruments. I could imagine myself prying one way when it is supposed to go the other. The one I pictured is now 40 miles away, but the next one I get might stay for a few years.

Thanks for linking your old post. I'd have thanked you there, but hate being the one to "bring up" an older post. :D

I can't take credit for figuring it out - I ran into an old picture posted by Jeff Suits (he is a member here) on another forum long ago that gave me the guidance on what not to do. I think I asked Jeff about it later and he didn't remember the job, so I was on my own!

If you run into another '70s Japanese laminated guitar, do consider hanging onto it. My Conn is very lightly constructed - every strum gets the whole body and neck vibrating. Due in part to that light construction, however, mine had a small belly between the bridge and soundhole, and a growing hump between the bridge and tail, but a Bridge Doctor put that right, and added some extra tone, as well. Sounds great, plays great. I wouldn't change a thing, and I expect to have it for the foreseeable future, something I can't say about most of the (way too many) other guitars I have.

As for the "zombie thread" issue, I've never understood why it's an issue. The things we're talking about come up time and time again. Nothing wrong with adding to an old thread to avoid that loss of collected knowledge. If I hadn't found Jeff Suits old thread, I'd not have known how to proceed on my Conn. Old threads, like most old people, have value.

ChrisN 11-14-2019 12:51 PM

Quote:

Originally Posted by Edgar Poe (Post 6211544)
That is a modification I make to ALL dovetail neck reset I do. I heard all kinds of remarks about how it ruins the tone. If anything in my opinion, it makes for a much more solid neck joint.

Ed

Ed, so I'm clear on what you're saying, what is the modification you're thinking of here? Are you saying you convert dovetails to bolt-ons? If so, and you cut through the neck to do your conversion, what do you do about the slight loss of scale/intonation?

I ask because I've got a RK (dovetail joint) that I like and may, one day, want to reset (it's great for now). I would prefer to do something that allowed me to do future resets more easily, rather than re-do the dovetail.

Edgar Poe 11-14-2019 02:26 PM

Quote:

Originally Posted by ChrisN (Post 6211556)
Ed, so I'm clear on what you're saying, what is the modification you're thinking of here? Are you saying you convert dovetails to bolt-ons? If so, and you cut through the neck to do your conversion, what do you do about the slight loss of scale/intonation?

I ask because I've got a RK (dovetail joint) that I like and may, one day, want to reset (it's great for now). I would prefer to do something that allowed me to do future resets more easily, rather than re-do the dovetail.

Chris, No I add the stud and acorn nut to the existing dovetail joint. The reason I started in the first place. I reset a neck for a friend, and being one of the first I did, I made some simple errors. After about a month of the neck being under string tension, and apparently I had not made the joint tight enough, possibly not allowing the joint to cure long enough, the joint opened up slightly. When I fixed it, I wanted to make sure it would hold. The stud and acorn nut make that possibly.

HOWEVER, YOU have given me an idea. I am going to take apart a cheap guitar with a dovetail joint. Make the repairs and install 2 or maybe 3 studs, and install the neck without Glue. That would be basically a bolt on neck.
Of course make the repair as if the neck would be set WITH glue, to make sure all angles are proper. If at a future time it needs further repair, the disassembly would be rather rapid.

Ed

ChrisN 11-14-2019 04:28 PM

Quote:

Originally Posted by Edgar Poe (Post 6211642)
Chris, No I add the stud and acorn nut to the existing dovetail joint. The reason I started in the first place. I reset a neck for a friend, and being one of the first I did, I made some simple errors. After about a month of the neck being under string tension, and apparently I had not made the joint tight enough, possibly not allowing the joint to cure long enough, the joint opened up slightly. When I fixed it, I wanted to make sure it would hold. The stud and acorn nut make that possibly.

HOWEVER, YOU have given me an idea. I am going to take apart a cheap guitar with a dovetail joint. Make the repairs and install 2 or maybe 3 studs, and install the neck without Glue. That would be basically a bolt on neck.
Of course make the repair as if the neck would be set WITH glue, to make sure all angles are proper. If at a future time it needs further repair, the disassembly would be rather rapid.

Ed

Re: Not gluing the fretboard extension on a dovetail - Keep in mind that the dovetail doesn't have the vertical mortise/tenon's ability to keep the fretboard extension from rising too much (creating fret buzz) against the tension added by shaving the heel base (to achieve the reset). Also, it may be the case that the glued fretboard extension may act as a structural support by transferring string tension to the soundboard, rather than letting the joint take the entire tension load. Don't know if that makes sense to someone who knows, but to me . . . . :D

Re: Not gluing the dovetail joint - I think if you had a really good fit, there'd be no loss of tone, and maybe on a cheaper guitar it wouldn't matter, but I'm sure those in the know may consider the joint incomplete without glue, resulting in loss of tone. I don't know. Just throwing it out there. Can't hurt to try it and see.


All times are GMT -6. The time now is 12:22 PM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Copyright ©2000 - 2020, The Acoustic Guitar Forum

vB Ad Management by =RedTyger=