Ron,
As far as I know, the carriage auto feed stop was only available on the
B-6. If there were any later models produced, I would imagine they
would have had it also. The B-4s didn't have a second shaft to drive a
worm gear. Although Rob Libby's B-5 has a second shaft, I don't see
the drum and collar for the auto feed stop.
The way it works is that the slotted shaft that drives the worm gear is
spring loaded toward the tail stock end. The spring is located in a
drum at the headstock end of the shaft. The collar can be locked with
a set screw anywhere along the shaft. When the carriage contacts the
collar, the collar moves the shaft toward the head stock end until it
disengages with it's drive gear. Naturally, when the shaft stops
turning, the worm gear stops turning and the carriage stops. I was
surprised how well it works.
Jim
