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PostPosted: Wed Feb 21, 2018 10:59 am 
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What is your preference for scarf joint design, style 1 or style 2 (alt)? I have been using style 2 (alt) but I wanted to get opinions... I like Style 2 because of the contiguous surface for the fingerboard. On the other hand, it does make a (somewhat) visible line on the side of the headstock...


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PostPosted: Wed Feb 21, 2018 11:09 am 
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Version 2 as well. I would not want the joint visible in the neck.



These users thanked the author meddlingfool for the post: Bryan Bear (Wed Feb 21, 2018 11:17 am)
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PostPosted: Wed Feb 21, 2018 11:20 am 
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I'm with Ed here.

IMHO, the visible joint on the side of the peghead looks better than the joint in the carved area of the neck shaft. If you end up using "ears" for the peghead you only see the grain difference in the endgrain.

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PostPosted: Wed Feb 21, 2018 11:43 am 
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Bryan summed up my thoughts.
In addition, style 1 requires resurfacing the top of the neck. Not in my skill set.
Style 2 requires a bit of planning so the joint ends up (on the back side) near the nut or at a volute to hide it, or a veneer can be applied.
If I have a prominent grain figure that will be visible, I’ll saw the head so it is not flipped in relation to the neck. (Opposite angle).

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PostPosted: Wed Feb 21, 2018 11:52 am 
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I didn't even think about the joint line on the front and back of the peghead because I always veneer both faces. Still, a joint line on the back of the peghead still looks better to my eye than in the neck shaft.

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PostPosted: Wed Feb 21, 2018 11:53 am 
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Brazilian Rosewood
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The scarf joint (alt) looks O.K. where you have a slot head and the tuner plates cover the sides of the peghead and the joint ends on the chin.
I don't care for having the scarf under the fingerboard at all or the short grain of the one piece.
So I'm stuck doing the modified bridle joint for paddle head guitars. [:Y:]



These users thanked the author Clay S. for the post: Bryan Bear (Wed Feb 21, 2018 12:13 pm)
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PostPosted: Wed Feb 21, 2018 11:55 am 
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It seems to be that the stress on the joint is also higher in design 1 though I am no engineer


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PostPosted: Wed Feb 21, 2018 12:20 pm 
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For me it's number 2, the joint on the head stock. Sound hole access to TR mitigates any structural/strenth issue, imo.
Photography can really draw your eye to what is usually an inconspicuous glue line. The second pic shows joint on head.
Ken


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These users thanked the author Ken Lewis for the post: Bryan Bear (Wed Feb 21, 2018 12:32 pm)
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PostPosted: Wed Feb 21, 2018 12:32 pm 
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#2 for me. I did one with the joint on the neck. Interesting look with the half moon across the neck, but not my thing.

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PostPosted: Wed Feb 21, 2018 12:38 pm 
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#1. this way i can nearly finish an entire headstock before glue up.

been thinking about bird's beak and bridle joints recently though.

just noticed that i'm "Cocobolo" -oily and allergenic.


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PostPosted: Wed Feb 21, 2018 12:55 pm 
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Brazilian Rosewood
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I have built all three and my all time favorite is number 1. Here are my thoughts

First, either scarf joint is much more economical of wood. We've all seen the pictures of how to nest several sawn one piece necks in a billet, there is still a lot of waste. And the nesting only works if you make all your necks basically the same size - I make everything from very short scale to very long.

Second, a one piece neck wants to break along the grain lines which Steve so carefully highlighted in his drawings. If you hog out a big area for a truss rod adjusted (again, right where the arrowhead is) you have a very weak area - it is the narrowest part of the neck and almost every break I have seen is right there. I put my adjusters in the sound hole whenever I can, but unfortunately that doesn't work for solid bodies or semi hollows or archtops or any guitar that doesn't have a sound hole. I build all of those and while I try to use a truss rod with the smallest possible adjuster it still ends up in the head.

Version 2 is better than a one piece neck as far as fracturing along grain lines but you still have a very weak area in that truss rod route. Version 1 addresses that - you have cross grain (actually angled grain) in the weakest part of the neck - I'll take that over a minor cosmetic glue line any time.

You can, of course add a volute or backstrap or both to strengthen the joint - I use the Martin dart style volute on necks where I think it looks correct - normally with a scarf joint I add it as a little block of wood that gets carved to shape. Again, there it a glue line but it is hardly noticeable. Remember that the origins of the dart is the "bird's beak" joint that Martin used a long time ago - another one of those elegant wood working joints that got lost.

The only advantage that I can see to the second variation is that the fretboard surface can be planed perfectly flat (sander, jointer, by hand) and maintained while you are making the joint. Version one requires you to glue the joint, then flatten it. This is a tricky joint to jig up - once glue is on it pieces want to skate around and clamping pressure just makes it worse. That can be even trickier if you are doing a laminated neck and want to carry the theme thru the head.

Version 2 is slightly easier to think about laying out the cut, in version one you need to make the short point the length of the head. In Steve's drawing the heads will be thinned (unless they are slot heads) - that moves the nut back a bit. I guess my answer to that is that every one here should be capable of laying out their cuts before doing it, but if you happen to cut version one too short you can always make a version two out of it.

Here are the cut pieces for a version one neck laid out my plans. The little piece under the joint will be the dart

Image

A neck for a Gibson style guitars, allen head truss rod adjusters, version 1 joints, stacked heels

Image

Here is version 2. It worked fine but I still think 1 is better

Image


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PostPosted: Wed Feb 21, 2018 1:50 pm 
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Freeman wrote:
Version 2 is better than a one piece neck as far as fracturing along grain lines but you still have a very weak area in that truss rod route. Version 1 addresses that - you have cross grain (actually angled grain) in the weakest part of the neck - I'll take that over a minor cosmetic glue line any time.

I've yet to have a scarf joint guitar come in the shop for a failure, much less a failure because of a version 1 design choice.. In my opinion the observation may be technically valid but in practice it is not an issue, as far as I've seen. Sort of akin to the dovetail vs MT neck argument.

Freeman wrote:
You can, of course add a volute or backstrap or both to strengthen the joint

This is really not necessary (same as above) in my experience. Add a volute for the aesthetic, but if a small triangle on the back of the neck is needed because of how one builds a neck, one might wish to rethink one's neck design.

In my experience, and Gibson wins for providing the reference standard, hogging out a big hole at the truss rod adjustment end is the winner winner chicken dinner for messing up a perfectly good neck. As a builder I also have a few other analog pet peeves. First I prefer the truss rod adjustment in the body, versus interfering with the headstock aesthetic, running the truss rod under the nut, etc. Second, I am not a fan of square bottom truss rods - they put a lot of pressure on a grain line point on a neck (think stress riser). I have seen these types of rods cause failures. Round bottom truss rods are much kinder to the neck ... which goes with Three - I prefer round-bottom routs for the necks - leaves more wood and takes the stress riser out of the channel.

Freeman wrote:
I use the Martin dart style volute on necks where I think it looks correct - normally with a scarf joint I add it as a little block of wood that gets carved to shape. Again, there it a glue line but it is hardly noticeable.

Gluing a piece of wood on the back of the neck is not going to increase the necks strength in any way, best as I can tell. Someone may correct me if I'm wrong. Necks crack mostly because they take a hit on the headstock, which is under significant tension. A stress riser often along a weak segment of the wood is the genesis of the crack. In the case of just gluing up a volute on the back, it's not "in play" with the neck and headstock which are under tension.

Freeman wrote:
The only advantage that I can see to the second variation is that the fretboard surface can be planed perfectly flat (sander, jointer, by hand) and maintained while you are making the joint.

Well, and one can place the scarf back in the headstock. Though honestly a well-glued scarf in V1 is not particularly visible.

Freeman wrote:
Version one requires you to glue the joint, then flatten it. This is a tricky joint to jig up - once glue is on it pieces want to skate around and clamping pressure just makes it worse. That can be even trickier if you are doing a laminated neck and want to carry the theme thru the head.

This is an issue of blocking the glue-up and a few other tricks (rub joint, progressive clamping). With a few techniques in play this goes together quite fine.

Andy


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PostPosted: Wed Feb 21, 2018 2:23 pm 
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I've done all 3 methods too and like all 3 methods pretty much just fine. 3rd method is classic. The 2nd gives an interesting look and the 1st is sort of standard. I like to bury the joint line in a valute of some sort when using the 1st method.


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PostPosted: Wed Feb 21, 2018 2:29 pm 
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"Gibson wins for providing the reference standard" i like that. they seem to be the reference standard for steady neck repair -both at the volute and the peghead. admittedly more so with electrics then with acoustics though.

method #1 while apparently ugly, makes the most of the re-enforcing effect of that large slab of hardwood called the fretboard.


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PostPosted: Wed Feb 21, 2018 3:36 pm 
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There is another method I've been thinking about that could be used to join the peghead and neck shaft that would be a cross between the scarf and bridle joint - kind of a hidden scarf joint. It would waste less wood and could be quickly cut on a tablesaw and with a router and simple jig but could be cut by hand too. It might work particularly well for paddleheads but could be used for slotheads too. if I get a chance I will make it and post some pictures.


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PostPosted: Wed Feb 21, 2018 4:48 pm 
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I had not seen method #1 until I started doing repairs in imported solid body electrics for a local store. As far as I knew, your 'alt' was the standard. A lot of those guitars ended up with a hump in the freboard over the end of the scarf, and some of them were also very hard to adjust the truss rod on, due to the difference in the way the two pieces of wood reacted. This may have all be more of a manufacturer's issue than inherent in the design, of course: those guitars were flashy but not well made. Still, I've never seen that particular suite of problems with the older layout, which you call alt'.

The truss rod adjustment inside the box is a real improvement, but there are times when you can't do it.

I have used a back strap on guitars from time to time, usually on one-piece necks where I wanted to reinforce the nut area. A veneer .1" or so thick on the back surface that runs up the neck for a way, say ending at about the third fret, helps to strengthen that short grain section where the fretboard ends. You bend it to go around the curve.



These users thanked the author Alan Carruth for the post: Bryan Bear (Wed Feb 21, 2018 4:57 pm)
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PostPosted: Wed Feb 21, 2018 9:43 pm 
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Glad I’m not the only one thinking through this right now.
All good comments and food for thought:)


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PostPosted: Wed Feb 21, 2018 10:49 pm 
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I agree with everything Andy said about my post but I'd like to clarify a few things.

- Yes, volutes are mostly cosmetic, I use them when they seem to fit the neck. Backstraps too, but are often used, along with or instead of, splines to reinforce broken heads. Here is one on a 12 string - obviously we don't have as much control over the preparation of the joint in a repair and that dozen strings are trying to pull the "joint" back open

Image

(the break in that neck is about where the joint would be on variation 2)

Again, I agree with Andy and several others who said that with an adjuster in the sound hole you don't need to weaken the head. I do that whenever I can, but I build Les Pauls and 335's and archtops and a bunch of other things where it simple doesn't work. I think this is where any scarf joint shines, and if you notice that Taylor, who puts the adjuster at the nut, uses one.

There could be a whole new thread about different truss rods and their effects on necks. There was a recent article in AL comparing different rods (it was about basses but should apply to guitars) - the authors conclusion was that the old bent compression rod really was best. Of course you have to hog out a big recess for the washer right at the weakest part of the neck.....

My version 1 joints usually have a little semicircle line that to me is not at all objectionable. My necks also have glue lines in the stacked heel - doesn't bother me a bit. Many of my guitars get color or shading in the finish - you can't see the joint at all.

My comment about the difficulty of jigging up the joint for gluing is intended at the several relative newbies who have been asking about it. A wedge is a wonderful mechanical system and with a little lubrication between surfaces and clamping pressure it really wants to slide. I've actually built a simple version of David Collins repair jig that I can use for both necks and headstock repairs.


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PostPosted: Thu Feb 22, 2018 12:05 am 
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I thought it might be interesting to look at how and where heads fail. Most of the time they fail because they get knocked off a stand (I hate stands but they bring me a lot of business). Sometimes they break all the way off (and sometimes the adjuster is at the nut, sometimes not)

Image

Image

Image

They don't necessarily break at the truss rod cavity or the tuner holes

Image

Some times its right at the start of the angle

Image

Slot heads break

Image

Sometimes the head plate holds everything together

Image

Mexican instruments break

Image

Banjos break

Image

And somewhere I have a picture of a three string Japanese instrument with a broken head. Happens to the best of them, how can we make ours better?



These users thanked the author Freeman for the post: TimAllen (Wed Apr 25, 2018 2:21 pm)
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PostPosted: Thu Feb 22, 2018 9:16 am 
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Freeman, Can you illustrate how you do the "volute" treatment you did on that 12 string? I like the look of that design and might want to use it on one of my instruments...

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PostPosted: Thu Feb 22, 2018 10:27 am 
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I don't have art work handy, but backstraps such as that one on the 12 are fairly straightforward.

Once you have the headstock glued on you have to level out the back surface. I use a drill press planer for that, taking it down to about 1/2" thick. Normally you'll want to finish to 5/8" for the tuners, so that gives a 1/8" thick back strap. Thin and level it as far down as the bottom end of the tuners, so that they'll have a nice flat surface to mount to.

The taper on the neck is also a flat. You're going to take no more than than 1/8" of thickness off the back of the neck at the nut, and taper that up nice and flat so that it feathers out to nothing somewhere down the neck shaft. How long to make this is something of a matter of judgement. IIRC, scarf joints in plywood for aircraft construction use something like a 20:1 taper: for 1/8" thick material you'd have a 2-1/2" scarf. This keeps the grain angle in the joint down so that it will hold under tension. This would run the taper on the back of the neck down to about the third fret.

So now you have two flats, on the neck and on the back of the head, with a space aboout 1-1/2" long between them. If you've been a good repair person and eaten all of your vegetables, they will be parallel to each other (you did check with winding sticks, right?), so that a cylindrical area will join them together nicely. I make that carefullly with files, although one could see doing it with a sanding drum. Just make sure the cylindar is really smooth and tangent to both flats; you don't want any dips or humps.

Once you've got that you can bend a piece of material to glue on. I tend to slightly over bend the curve. I like to make up a caul to match the cylindric section, a flat for the headstock, and a wedge for the neck part. Don't forget the backing cauls as well. If you did all the prep right it should just go together nicely. Use plenty of clamps.

Don't ignore the decorative possibilities in this. They used this on a lot of old banjos with 'V' neck profiles. The neck would be a 5-piece lam, say a maple center stripe, walnut veneers, and maple for the bulk. Using a maple backstrap with a walnut veneer ties in nicely.

I actually think that a back strap on a one-piece neck is stronger than the usual head plate.



These users thanked the author Alan Carruth for the post: Bryan Bear (Thu Feb 22, 2018 11:08 am)
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PostPosted: Thu Feb 22, 2018 12:31 pm 
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sdsollod wrote:
Freeman, Can you illustrate how you do the "volute" treatment you did on that 12 string? I like the look of that design and might want to use it on one of my instruments...


I did a "backstrap" on the 12 string, pictures in the next post. I did a dart volute on the slothead 00. Here is the neck shown on the drawing with the pieces all glued together. The "volute" is just a little piece of scrap mahogany glued across the joint

Image

Starting to carve

Image

Image

Image

Image

Image

If you squint really hard you can see the half circle glue line that everyone is objecting to - yeah, thats what I thought LOL


Last edited by Freeman on Thu Feb 22, 2018 12:51 pm, edited 1 time in total.

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PostPosted: Thu Feb 22, 2018 12:44 pm 
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Alan Carruth wrote:
I don't have art work handy, but backstraps such as that one on the 12 are fairly straightforward.



The worst part of this was trying to balance a 12 string guitar while I fed the head under my Safe-T-Planer - my advice is to do this before the neck is on the guitar.

Image

It probably wasn't necessary but I did put a little piece of carbon fiber across the break (with epoxy), then there is a filler piece of wood to help make the curve onto the neck. Took some scrap mahogany and put a little bend in the end and sandwiched the whole mess together. FWIW this is a Guild with two truss rods.

Image

Often backstraps are a decorative touch but I wanted to hide the repair. As usual the hardest part was matching color and repairing the poly finish

Image

Image

I'll just add that the repair is probably three years oid and I saw the guitar not to long ago. It is holding up fine under 250 pounds of string tension and the owner is just playing the heck out of it.

Here is the same idea done as decoration (and maybe a tiny bit of structure). Done the same as the 12, ran the neck under the Safe-T-Plane, worked the curve into the neck shaft by hand, glued a contrasting veneer on (veneer matches all the rosewood trim used on the rest of the guitar). There is no volute

Image



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PostPosted: Thu Feb 22, 2018 1:37 pm 
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Great posts! I learned a lot going through them. I have been doing 2 and 3. I always do 2 for a classical I mostly do three for my steel string. I have no wisdom for why.

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PostPosted: Thu Feb 22, 2018 2:42 pm 
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If I scarf then 2), But normally I use one piece necks, 15 degree slope with a volute and backstrap.
Truss rod adjustment is at the headstock, (6mm x 8mm deep slot), plenty meat in the area.


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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.


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