Mick, the only one where I went bolted was a couple years ago on this interesting, but strange brace-less, mahogany top thing, where obviously making a serious mistake was inconsequential. I did detail it here, but not with process photos. Basically, the neck is sawn off, not out of necessity, but because I needed to raise the entire fretboard in order to get some good breakover angle at the bridge, the soundboard being completely flat.
Internally, I measured and made a fairly thick plywood bulkhead to completely cover the back of the neck block, which was cracked and probably too weak. Then, making a long alignment tool with drill inserted from the tail end, located a clearance hole for a bolt in the new wood and through to the still detached neck. A furniture-type brass threaded insert went into the neck as low as reasonable, with epoxy on the external thread. A slight angle correction is sanded on the end of the neck by inspection.An allen bolt and large washer went inside the bowl, and since there’s an oval hole, tightening and adjusting was easy. The fretboard extension, raised with a shim about 1/4” is then clamped in best alignment and glued. Note that the board itself didn’t have to be removed at all, none of the staves was disturbed and the top stayed on. Once adjusted, it was taken apart and the flared part of the neck glued in for added stability. A brace was added to the mahogany top. I wouldn’t call this a high-skill repair, just an experiment. Plenty strong at a guess, and no acoustic implications. It is a different sounding thing, but aren’t they all?
For a more ‘normal’ bowlback where visible surgery would be ugly, I’d definitely remove the fretboard first and analyze the neck connection, but still saw it off forward of the stave ends and bolt through from the inside.
Wildwood even bolts from the outside and plugs the hole, which is easier, and very likely a coarse wood screw could be strong enough if the neck block was sturdy, but using a nut and bolt plus a bulkhead is both adjustable and stronger.
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