This particular guitar is a Bel Son No. 36 made in Brasil in 1976. I understand it was the highest production line model available at that time. Higher spec’s models were supposedly handmade.
The bridge I believe is a nice piece of Brazilian rosewood and maybe the fretboard as well. Bottom and sides are two ply laminate with the top ply most likely being Brazilian rosewood. The top is a very thinly cut type of hardwood.
The top is unusual for an acoustic guitar and has deformed over the years, ie, it is no longer flat and has ‘sunk’ around the fretboard section and around the bridge. This caused the action at the 12th fret to be around 6mm high and made the guitar unplayable. Look at how low the neck plane ‘sits’ on the bridge.
Click on the photos to enlarge them.

The neck heel and its angled, narrow section within the body suggested this guitar had a so called Spanish heel – the heel being glued in with the sides and not using a dovetail. The latter requires a much wider heel base inside the body. Anyway, it turned out to be neither as the photos below will show.
Here the neck reset calculations:

Assuming it was a Spanish heel, I used a small saw blade of which I had hammered down the ‘set’. So initial saw thickness was 0.6mm but afterwards it was reduced to 0.3mm so as little as possible of the heel was removed.

After cutting through the heel, the fretboard needed to be loosened from the top. I used a large bit of steel from a woodsplitter that had been sitting in boiling water for a while to loosen up the glue.

I did not use the tool shown above but a much better one. No photo sorry. The fretboard came off without too much damage to the top. Notice that it is not a Spanish heel but there is also no dovetail! It is just a rectangular bit of wood that was glued into the heel and into the heel block inside the body.

And in the following photos you see what a crappy heel connection it was… As they say, probably made at 4pm on a Friday afternoon. Didn’t know that attitude existed in Brazil…
Look at that huge gap on the right!

No dovetail! No more than 15mm inserted into the heel block.

I have no photos of the actual reset of the neck heel. Suffice to say that it is very laborious with lots of incremental fitting stages: ie, removing small bits of wood, then trying, etc, etc. Obviously with the neck sawn off, another way of reconnecting it back to the body is required. This neck is going to be reattached with two bolts just like Collins and Taylor guitars do. On top of that, the heel and fretboard will be glued back to the body as well with fish glue.
When a neck is reset, the fretboard bit over the body moves up, so a tapered sliver of wood is required to fill that gap. The one below is cut from a piece of Fijian mahogany.

And below the rough sawn sliver resting on the neck. It needs sanding and shaping for a nice fit before it can be glued onto the bottom of the fretboard. Note the brass insert in the heel for bolting the neck on.

Sadly no photos of the bolting and gluing the neck back on, but below is the finished product. Note that the original plastic saddle has been replaced by a proper bone saddle.


After the neck reset the action at the 12th fret for the high E is 2mm

After the neck reset the action at the 12th fret for the low E is 2.5mm

A couple of photos of the bone saddle I made from scratch.


And here a photo of the headstock with new strings wound on and the finished guitar itself!!



So was this worth it? In my opinion no. The guitar’s construction and hardwood top are not indicative of a high quality guitar and the work involved is ‘huge’.
Was it satisfying to do the neck reset? Yes, if you can do this yourself then there is no ‘financial burden’ if you enjoy doing this kind of work.
The below labour log shows the hours required. I am sure that it can be done a bit faster but this is what it took me:
