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 Post subject: Neck Set Story
PostPosted: Sun Dec 10, 2017 8:43 pm 
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Joined: Sun Jun 25, 2017 3:58 pm
Posts: 290
Location: St. Louis area
Hi everyone. I've been working this neck for weeks now. Had a "targeting" error and when I thought I was done, I did not calculate correctly. Then, Neck was offset 1/4 inch from centerline at bottom of body. Now the neck angle is correct, the yaw, or centerline is dead on but I need .080 thick shims at the heels to pull it into the body. End opposite the heel ( maybe I'll call it the hell) does not need so much, so in essence I need a monster wedge to pull the neck in.

So I have no idea how to proceed. Is the wood type of the wedge important? I could stack up laminate three or four layer of the .025 walnut veneer I have. I could tablesaw a piece of ash to .080 or so, with no wedge and just use the chalk method to fit it.

Also, the final cheek fit is not perfect, I can slide a thin paper under the joint in places. How perfect must it be? I've included a picture. I've got to stop sawing on this neck joint while I have some neck left.


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Last edited by Kbore on Tue Jan 09, 2018 11:25 pm, edited 1 time in total.

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 Post subject: Re: Neck Set Issues
PostPosted: Sun Dec 10, 2017 9:01 pm 
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Joined: Wed Aug 13, 2014 12:14 pm
Posts: 1340
Just add shims to the sides of the dovetail joint until it pulls up properly. I have always had to shim the joint on the guitars I've built. It's not a big deal.

I'm currently doing a neck reset on an old Harmony Sovereign. When I took it apart, the joint was tight, with no shims. After I sanded down the contact faces of the heel to adjust the neck angle, the joint became "a rattling good fit." Totally loose. Not a problem. I'll just add a shim or two until it pull up tight. When I find eh right combination of shim thicknesses, I'll glue the neck and the shims all together, at once.

Oh -- type of wood for the shims. Not particularly important. Just something solid that glues well.

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Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion


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 Post subject: Re: Neck Set Issues
PostPosted: Mon Dec 11, 2017 7:26 am 
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Joined: Fri Mar 03, 2006 7:09 pm
Posts: 6237
Location: Hegins, Pa
don't worry so much on the cheeks as the finish will lay on the surface and you will have to scribe that in later.
as Maingeeser said anything that glues well will make a good shim

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John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com


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 Post subject: Re: Neck Set Issues
PostPosted: Mon Dec 11, 2017 9:50 am 
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Joined: Sun Jun 25, 2017 3:58 pm
Posts: 290
Location: St. Louis area
Thanks guys.
John, what does “scribe it in later” mean?
Should pulling the neck at the headstock ( pretty hard) cause a .003 gap at heal? Does the cheek need a little more work?

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 Post subject: Re: Neck Set Issues
PostPosted: Mon Dec 11, 2017 10:53 am 
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Joined: Thu May 24, 2012 8:03 am
Posts: 1430
Location: Chestertown Maryland
KBore

Something to think about is that when the strings pull on the head of the neck, it stretches open the bottom of the joint but it pushes closed the top of the joint - so a tight fit is most important at the bottom.

So get the joint as tight as you can make it against the body - floss, try, floss, try.

Then use chalk on the surfaces of the dovetail, work it down into the joint, wiggle it, pull it out, and you will see where contact is made on the surfaces of the mortice. You have to have the contact at the bottom of the joint to jeep it from pulling open, but full contact at the top is less important. Once the joint is tight, do final floss - as little as possible to keep from needing another shim.

And violin makers will only use willow for shims - tradition is a mighty force.

Ed

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 Post subject: Re: Neck Set Issues
PostPosted: Mon Dec 11, 2017 11:29 am 
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Joined: Sun Mar 09, 2014 8:13 pm
Posts: 2322
Any wood works for shims. I have a package of maple veneer that I bought for something else. I just cut it with scissors and stick it in the joint. You will want to make sure that the heel is pulled down tight. Shims are the answer. I don't glue my shims until I glue the joint. I just lay them in there while fitting. The joint changes, sometimes necessitating changes in shimming.

Scribe sanding is the last step. It will make your neck conform to the shoulders of the guitar. You use strips of sandpaper, which you'll pull through the overhang of the neck, between the overhang and shoulders, with the sand side up toward the neck.

Here is John's video. In fact, he has a series of 5 videos on neck setting, which are invaluable.

Scribe sanding is at 35 seconds into this video:

https://youtu.be/dJYegLrcqA4


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 Post subject: Re: Neck Set Issues
PostPosted: Mon Dec 11, 2017 11:47 am 
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Joined: Wed Aug 13, 2014 12:14 pm
Posts: 1340
If you aren't already doing so, try putting a clamp on the joint and pressing it together before you test for movement. I find that it's difficult to keep keep the dry-fit joint really tight without a clamp. Even if there is no obvious movement, it may still have opened slightly, which could lead to the 3 thou movement you're seeing.

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Don't believe everything you know.
Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion


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 Post subject: Re: Neck Set Issues
PostPosted: Mon Dec 11, 2017 9:04 pm 
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Joined: Fri Mar 03, 2006 7:09 pm
Posts: 6237
Location: Hegins, Pa
check out this link
https://www.youtube.com/watch?v=FNcbA1P95KE

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John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com


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 Post subject: Re: Neck Set Issues
PostPosted: Mon Dec 11, 2017 9:49 pm 
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Joined: Sun Jun 25, 2017 3:58 pm
Posts: 290
Location: St. Louis area
tippie53 wrote:


Ahh, the addendum... I’ve viewed that many times. The only thing missing was my mistakes! Ha.

I really feel it necessary to glue then remove shim material Since I have a tapered fit, and it is large and complex. I want to glue shims first, then remove material with 80 grit. I’ve done the “A” and “C”.. moving on to “E” elevation. Attach shims to tenon or mortise ( there seems to be differing views of this)?

Thanks for the replys!

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Karl B


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 Post subject: Re: Neck Set Issues
PostPosted: Mon Dec 11, 2017 9:57 pm 
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Joined: Fri Mar 03, 2006 7:09 pm
Posts: 6237
Location: Hegins, Pa
feel free to call me

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John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com


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