Noddy wrote:



What I was wondering is how interchangeable are the top and bottom
halves of Series I & II Bridgeport heads?
Nope, won't work. The spindles are different. Due to the height
of the varispeed drive, the 2J spindle is longer, the splined part
sticks up higher to where the driving spline is. Then, the rest of the
spindle is a lot longer, so the longer drawbar is at the top of the head.
I'm not sure how many other critical differences there are, but this
is the big one.

Oh, this is not a series-I vs. series-II difference, this is 1J vs
2J. Most series-II machines have 3 or 4 Hp motors and are completely
scaled up from the 1J and 2J heads. Series-II heads (3J and 4J)
typically have NMTB 40 taper, never R-8.

Jon