kneenut wrote:
I am interested in machining and read this ng everyday but... being ingorent
about machining, what is the difference between types of lathes,
mills...ie., gap, engine, turrent, knee etc.
A gap-bed lathe has a section of bed ways near the
headstock that is removable, for turning large
discs that would hit the bed otherwise.

An engine lathe is as opposed to a bench lathe,
where the bed is just bolted to the bench. The
engine lathe has some sort of a pedestal as part
of the machine, sometimes two completely separate
pedestals at either end of the bed. Or, it may
imply a geared headstock.

A turret lathe has a tool turret on the
carriage/cross slide, and generally has no
tailstock, as the turret is often tall and wide
enough to block material from passing over it.
There is usually some system like a turret stop on
each axis as well.
It is used for production work on relatively short
parts.

A knee mill would refer to machines like the
classic Bridgeport.
It has a "knee" that elevates the entire X-Y table
and the work.
The Bridgeport is called a "turret mill" by the
maker, due to the swivel arrangement at the top of
the main base casting. That swivel is not used
much at all in most cases, but can get you out of
a jam on a huge workpiece. So, the turret there
is totally different than the turret on a lathe.

Some other machines elevate the head by a variety
of means to compensate for fixture and workpiece
height, and tool length. There are benchtop knee
mills, like the one of the Burkes, I think. Many
benchtop mills elevate the head to adjust height.

Jon