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PostPosted: Fri May 17, 2019 1:11 pm 
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Koa
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Location: Cowichan Valley, BC, Canada
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I'm working on my second one of these. I'm noticing that my transition from headstock to neck has a pretty sharp angle, and that because of that I'm left with a small gap where the transition happens underneath the bent back strap. Any tricks on easing that transition into more of a gentle curve without creating a little dish at the base of the headstock?

I know you can't really see what I'm talking about from the pictures, but hopefully it helps make my question a little clearer.


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PostPosted: Sat May 18, 2019 5:23 am 
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Contributing Member
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Location: Southeast US
City: Lenoir City
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Looks to me like you need to add some wood to clean up that curve before you put on the backstrap. When I need to build up old headstocks or necks I use mahogany (or maple) veneer. I like the veneer because it will conform well with curved sutfaces. I usually make a caul to fit the shape with some cork facing and glue and clamp the veneer. Just glue several layers of veneer over the area of the dip and then reshape it so the curve is the way you want it for the backstrap. A disadvantage here would be the need to recolor the edges of the headstock if you were wanting to avoid that since the veneer won't be an invisible repair.

Looking at that again I might take a different approach and just ease the curve into the neck with some careful work using a chisel, file, etc and sanding block. Then just make the new backstrap thick enough to make up for any missing wood.

Don't know of any real easy way.

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PostPosted: Sat May 18, 2019 5:56 am 
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Brazilian Rosewood
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I typically never run my back graft so far down the neck. That thin sliver will leave a wide glue line at the edges that will be tough to cover with finish.

I also custom make every graft from solid wood shaped to fit the back of the headstock proper with very little pressure. Like I do here https://howardguitars.blogspot.com/2015/08/the-bondo-cutaway-or-why-i-hate-bondo.html

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PostPosted: Sat May 18, 2019 8:11 am 
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Brian, this post on your blog is awesome.


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PostPosted: Sat May 18, 2019 10:50 am 
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Koa
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Here is one that I did a while back. After gluing the crack I planed about 60 thousands off the back and bent a piece of mahogany to fit. The dark thing is a piece of carbon fiber that I epoxied right over the break as a spline (remember the Guild 12 string has two truss rods) - I don't think it does any good but it made the owner feel better. There is a wedge of mahogany over that to make the curve better for the back strap to be glued to.

Attachment:
IMG_3457.JPG


Attachment:
IMG_3459.JPG


This repair is 3 or 4 years old and shows no sign of opening back up even under the tension of the twelve strings.


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PostPosted: Sat May 18, 2019 1:01 pm 
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Koa
Koa

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Location: Cowichan Valley, BC, Canada
First name: Conor
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State: British Columbia
Zip/Postal Code: V9L 2E5
Country: Canada
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B. Howard wrote:
I typically never run my back graft so far down the neck. That thin sliver will leave a wide glue line at the edges that will be tough to cover with finish.

I also custom make every graft from solid wood shaped to fit the back of the headstock proper with very little pressure. Like I do here https://howardguitars.blogspot.com/2015/08/the-bondo-cutaway-or-why-i-hate-bondo.html


Thanks for reminding me about this post Brian, I've seen it before, but I'll read it again. Just looking at the photos makes me break out in cold sweats. I need to add your blog to my list of bookmarks for when I need to do some reading on different techniques and repairs. The title makes me chuckle though, I remember watching a guy on youtube talk about his process for building guitars, and he was so casual about tear out from a router, his solution, "Oh well just slather it in bondo, and hide it under a solid color, everyone does it."

I used a tutorial on Frets.com as my primary resource, he mentions taking the back graft a little past the first fret, I admit I ended up going further than that. Oops. I'll be more careful next time.

In the tutorial Frank mentions using a safe-t planer to thin the headstock which I did, and then a draw knife to bring the graft a little past the first fret, which I didn't do (I don't have one I used a block plane, chisels, and scraper). Anyway I'm assuming he ended up with a gently curved surface, while I ended up with two flat surfaces that have met together creating not a totally sharp transition but too sharp for a piece of bent wood. I assume wood doesn't bend well to a specific angle but must be a curve. Am I wrong in that? Anyway I can see how a draw knife might be a better tool for this job, but in lieu of that I think I'll try building up that transition a little bit, and then a little patience and a chisel, and scraper I should be good to go.


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PostPosted: Sun May 19, 2019 5:22 am 
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Brazilian Rosewood
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I use a safety plane to rough off the material needed and then finish with a 2.2" sanding drum to give ma a nice glue surface. This also forms a perfect radius where I stop it on the neck shaft making mating a new piece seamlessly very easy. I typically try to go no farther than the first fret. Preferring to stop in the middle of the nut and 1st if the break will allow. But every break is unique and so must every repair be.

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These users thanked the author B. Howard for the post: Conor_Searl (Sun May 19, 2019 7:00 pm)
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PostPosted: Sun May 19, 2019 7:03 pm 
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Koa
Koa

Joined: Fri Feb 10, 2017 11:09 pm
Posts: 585
Location: Cowichan Valley, BC, Canada
First name: Conor
Last Name: Searl
City: Duncan
State: British Columbia
Zip/Postal Code: V9L 2E5
Country: Canada
Status: Semi-pro
B. Howard wrote:
I use a safety plane to rough off the material needed and then finish with a 2.2" sanding drum to give ma a nice glue surface. This also forms a perfect radius where I stop it on the neck shaft making mating a new piece seamlessly very easy. I typically try to go no farther than the first fret. Preferring to stop in the middle of the nut and 1st if the break will allow. But every break is unique and so must every repair be.


Brilliant on the sanding drum Brian. I sure appreciate you (and so many others on this site) who are quick to help with such thorough responses, and who never make me feel stupid. I don't think I've felt talked down to once on here.


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