Please forgive me if this is a stupid question, but what is a second
operation lathe? I have a nice Circa 1980 South Bend Heavy 10 lathe. Well
tooled, but I a have the bug, and I am always looking for a larger more
rigid lathe. I am always perusing ebay and local ads for lathes. I come
across a lot of Hardinge 2nd operation lathes and I am confused by the term.
Would love to get my hands on a LeBlond, Clausing, Hardinge, Pratt & Whitney
or Monarch to compliment my SB.
Thanks for the insight.
Basically, a second operation lathe is used to perform turning
operations on a workpiece which has already had some work performed on
it in another lathe. Often, the second operation is used to finish the
end by which it was held in the first machine.
A second operation lathe will not be likely to have a tailstock,
(although it may have a bed turret), and it may not have thread-cutting
Before I got my 12x24" Clausing, which could handle the stock
through the spindle (and which has both a bed turret and a tailstock,
and thread-cutting capabilities), what I used to do to produce one
particular part was:
1) Cut workpiece to length from round bar stock (3/4" brass,
FWIW) using a bandsaw with a length stop.
2) Mount that in a chuck with soft jaw turned to fit and to provide
a depth stop, and face the workpiece, followed by center
drilling, through drilling, and tapping. This was done in a
Taig, FWIW, for which *all* 3-jaw chuck jaws are soft jaws -- at
least from the manufacturer. I simply ordered a few extra sets
for special work like this.
3) I then moved the workpiece to a Compact-5/CNC, with a special
arbor fitted with a threaded extension to match the thread in
the workpiece, and a cam to lock the workpiece firmly against
The CNC lathe was programmed to face the now free end, turn the
OD down to 5/8" (except for a flange left at the end), thread it
at 5/8-27, cut a relief groove att he flange, since threading
all the way to the flange was not possible with the existing
The Compact-5/CNC was being used as a second-OP lathe, even
though it was not designed to be one.
As it worked out, the CNC lathe could turn out its more complex
half of the job (without my hands on it) in about the same time that it
took me to perform the simpler first operations on the Taig (the
bandsawing was done for the whole length of rod before the other work
started). Thus, running the two machines at the same time, I was able
to complete a lot more parts in a given time.
Normally, a second operator runs the second-OP lathe, and a
third (lower-paid) person carries the workpieces from one machine to the
As it turns out, I now make that part entirely on the Clausing,
using the bed turret. A box tool turns the diameter down. The
center-drilling, drilling and tapping are done by other tools held in
the turret, and the external threading is done in a single pass with a
Geometric style die head, rather than having to be single-pointed with
more passes on the little CNC lathe. The only thing that the
cross-slide does is cutting a groove to end the threads at the flange,
and parting off the finished object.
Also -- the Clausing even has a station free for a knurling
head, so the edge of the flange is knurled as well. Next batch, I will
be trying out a nice cut-style knurler, which looks kind of like a 3-jaw
So -- essentially, a second-OP lathe is defined by its use --
but its normal use means that there are some features which are
necessary in a toolroom lathe which are not necessary in the second-OP
I consider having the bed turret as an alternative to the
tailstock on the Clausing to be quite useful. I currently don't have
room for a second-OP (by design) lathe. The Compact-5, and the Taig are
both quite small machines -- a maximum swing of 5" on the Compact-5, and
the Taig is a machine which I can run in my lap if I so desire.
If you have production runs which could benefit from having a
second-OP machine -- you can get them for a lot better prices than a
And it may be worth while just for those occasional things which
have to be done while your main lathe is already tied up with another
project -- if you can live without a tailstock. If it has a turret, it
can use Geometric die heads (or other similar designs) and do threading
even without a longitudinal leadscrew. But beware that you know what
you *aren't* getting with a second-OP machine. I've never had a chance
to get my hands on one designed from the ground up as a second-OP
machine, so there are probably features which I don't know about, and
hopefully people who have used them will toss in information -- but at
the moment, I don't see any other replies yet which have reached my news