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I was recently told, by a luthier supplier, that the new approach to the spanish heel neck joint was to curve the receiving slots in the neck-block to match the outer profile. Meaning that the sides would be cut on a curve to fit the slots. I have never seen, read or heard anything like that - so please, have I just been missing something or are my legs being pulled out from under me?

I'm not sure I understand what you are getting at. Are you saying that the slots have a curve that follows the curvature of the upper bout of the plantilla as it approaches the neck? I can't see adjusting for this as having much of an effect. Sort of the same think as compensating for the front-to-back twist on the sides, and resulting slight skewing of the box geometry, implied by adjusting the neck set angle - you can do it, but the distortion isn't really enough to notice if you don't.

Oh, wait (he edits) ... Are you saying that the sides are tapered to more or less follow the taper of the heel from fretboard to heel cap?
This is more or less standard - you want to keep as much meat in the joint as you can, so you slot the heel block leaving more unsawn width under the fretboard than at the other end.

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Jim Kirby
kirby@udel.edu

The slots are cut at an angle that equals about a 4* slant to the cernterline of the neck. This angle accommodates the angle of the sides as they enter the neck. The slot, however, is cut perpendicular to the top of the neck. All of this is pretty standard. I don't know anyone who cuts slots that curve, though there may be someone.

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Waddy

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I guess if you want a difinitive comment, you would have to ask your luthier supplier to give you a sketch of what he means. As the others noted, following the curve could mean following the shape of the neck, or following the shape of the side, or maybe following the shape of something that I cannot picture. The only instances I know of where the "slot" follows the shape of the sides is not really a "slot". Many makers assemble the box separately from the neck. The neck is then shaped to fit the box and attached with a spline.

Waddy, are you saying you leave the connection between the internal heel block and the external heel of equal thickness from top to back? Nah, I don't do that. I definitely leave a connector that is wider under the fingerboard than at the back. (I'm just doing a 2mm slot, though, not a full cutout for a double wedge.) The cut has a straight bottom though - it doesn't follow the curvature of the external heel.

I'm looking at the neck for a project I'm working on now, a Greg Byers' style guitar with elevated fretboard. This is cut for a double wedge, and the spine or connector between the inside and outside is triangular - about 15mm wide at the top tapering down to nothing at the back. So even with a double wedge I'd definitely have a wedge-shaped taper to the sides as they join the neck.

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Jim Kirby
kirby@udel.edu

Well, not necessarily curving slots, but slots that leave a wider 'connector' at the fingerboard end of the neck than at the heelcap are pretty common with a Spanish heel.
I can't turn up my copy of Sloane just now, but that's my recollection of the method I used when I built my first guitar to his instructions in 1976. Just to be clear- what I think Jim Kirby and I are talking about is a slot that requires the ends of the sides to be cut at an angle, not square, where they join to the neck. This has nothing to do with the curvature around the upper bout.

I had a quick check on my bookshelf, and found that Natelson (Cumpiano & Natelson) recommends a non-tapered (& narrow) 'connector' in the Spanish heel. Authors who specify a wider 'connector' at the fingerboard end:
Courtnall
Bogdanovich
Overholtzer
Bouchet

Probably either way is strong enough....

Cheers
John

Im not sure if im barking up the same tree here
The last neck I got from LMI the slots were curved inside neck block.
I put it down to the manufacturing process as the curve was exactly that of a 10" tablesaw blade.
I used a blade as a template to cut the sides and ge a good fit.

That's the way Overholtzer cut the slots, though I think he used a smaller blade- in his book, his slots were straight for a way, then curved up toward the fingerboard. He shaped the heel in the same way, then raised the blade to cut the slot.
Though he was pretty far from the 'mainstream' there are some interesting ideas in his book.

I was thinking curve, as curve of the sides as they entered the neck/heel joint, as they are not square, not curve where the neck buts into the spline of the joint left in the neck. I definitely leave my spline wider at the top of the neck vs the bottom of the heel. I also use the wide slots and wedges, and if you cut the slot with a table saw, or RA saw, and it was curved in there, it would be a pain to match up to the sides for mating. I actually cut mine with a table saw, but it's a through cut, not a cut to the apex of the saw blade.

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Waddy

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Sound Clips of most of my guitars

I would need to see this curve to properly understand what, exactly, is being curved. I can't see any advantage except to justify a production process. Leaving the connector wider under the fingerboard than at the base of the heel is standard and just good common sense.

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I think these responses vary, which is probably cause I can't express it well. What I've seen in all the books I've looked at is the width of the neck that passes thru to the block is the same under the fretboard and at the heel cap. That was pretty much what I was taught years ago. Based on responses it sounds as though that has changed so that the neck/block slot varies in width (curved or straight)?
thanks

Ed-
I'm not sure that this is a 'modern' thing at all.
Which books have you looked at, that call for an untapered 'connector' between the 'neck' and the 'block' sections? (Aside from Cumpiano&Natelson if that is on your list...)

Cheers
John

OK, glad someone mentioned Cumpiano, I've got the paperback 1993 Chronicle version, pp 51-53, he uses the term "web" to describe the area I'm confused about. He leaves a width of 7/16 for the web, at the heel cap point and at the fretboard. That's the area I've been told is now curved - someone said they had received a kit with the web curved to match a 10' saw blade.
So my question is whether or not that is the "new" way or if folks are using the constant width of the web? (Did I describe that better?)
thanks
ed

No, almost everyone uses a web (thanks for coming up with the terminology) that is wider under the fretboard, with or without curvature to the cut in between.

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Jim Kirby
kirby@udel.edu