I chatted with Richard Brune about this topic, and here's what he told me about this neck attachment method. He said it was OK to share it with you folks since he is not on DelCamp:
"My machine is based on the one that was used by the Asturias shop in Japan, and I published an article ('The "Belly Art" of Japanese Lutherie')about this shop in American Lutherie # 15, Fall of 1988, based on my 1988 lecture for the GAL.
Actually I began using this neck system back in the 70's. In the 60's I became aware the Japanese were using something like this because it is much more efficient when in a production mode vs one or two at a time. My first machine was a four roller contraption with the belt running across the neck in line with the grain of the side wood, around the circumference of the guitar body, but only touching the body where the heel needed to be sanded. It was cumbersome, hard to perfectly align the neck and the sanding belt tended to make the heel deflect a small amount in the direction it was running, but it was still a pretty fast system once you knew the pitfalls. I showed it to Bob Ruck who made a similar machine and started doing his this way, too. When I visited Japan back in 1985 to meet the Asturias folks who were making two models for me at that time, and I spent time in their shop which the article I referenced covers. When I saw their neck machine the light went off and I said I've got to make one like that. The 3 roller wheels are from Woodmaster who also made the long stroke sander I use. The secret is having the roller wheels all crowned significantly which helps to keep the belt tracking to the center rather than trying to walk. The rest of the hardware is off the shelf shafts, bearings and such from Grainger, with a plywood frame designed to hold everything in alignment. Its totally trouble free, works even faster than Marshall's demo and is so reliable we never even have to check the centering nor neck angle projection before we glue them up. Never had a neck come loose. We glue them on with hot hide glue, although realistically I never intend the neck to be removed, gracefully or otherwise. We've never had a Japanese guitar in the shop needing a "neck reset" due to neck angle problems, including steel strings. They just don't creep."
There you go... straight from the master himself. I'm very privileged to be able to consider Richard a friend.
I build in a similar method (neck separate from body), but use a very different contraption for the neck joint. I learned from Peter Oberg who learned from Ruck, so I guess I'm a fourth generation builder using this method from Richard. Peter modified his jig to use a sanding drum on a drill press with a neck holding jig that is profiled to put the correct curve on the heel to match the body, and I use that method as well. It requires a few additional minutes of flossing to get the final fit to handle minor body variations. But at our low production rates and tiny shop spaces, it makes sense to save the large area required by this neck jig for something more compact.