Milling keyways in a long shaft?

[big job]

Common procedure here with long marine shafting. We simply use
a pipe vise. We have machined various jaws. We have two large
"Reed Vises" our tables are 10x52 and fits tee slots perfectly. We
index the vise, call it a tail stock vise. With some blue'en
and some scribe marks and two fixed pointers, thats about it. So
save that ole pipe vise. Then an emergency home owner comes in
to tread a 1inch pipe thread, no problem to thread on the mill
table (we have dies) and you aint going to tip over a 3,000lb
mill. Just one more hold down fixture for the draw.. Not being a
fanatic, but we even put a Cincinnati decal on these two.