From: (DoN. Nichols)
Organization: D & D Data, Vienna, VA
Reply-To: (Donald Nichols)
Newsgroups: rec.crafts.metalworking
Date: 11 Mar 2005 22:26:47 -0500
Subject: Lathe tool post question
In article ,
Daniel A. Mitchell wrote:
ATP* wrote:
"Jaggy Taggy" wrote in message
...
On my recently acquired Reed & Prentice lathe is an old style tool holder
(lamp post style??) which really sucks.
But the alternative, get a modern stable setup, is a bewildering task.
There
are many styles and a large swing in prices.
My lathe is a 12"
[ ... ]
You'll probably be happy with the cheaper Enco kit, which goes on sale at a
substantial savings periodically.
[ ... ]
I've had good luck with the wedge type Phase-II toolpost. The wedge
posts are a bit more expensive than the piston type, and a bit more
rigid, all else being equal. Phase-II makes both types. The toolholders
are the same for either type. That said, many are happy with the piston
posts for occasional or lighter work.
For a 12" lathe you'd likely want the '200' series (aka; "BX' series) size.
I agree with both choices -- as they match the ones which I made
for my 12x24" Clausing -- 200 series Phase-II (same as BXA size for
Aloris and some other brands, whose tool holders you can also use with
the Phase-II toolpost).
My considerations we
1) The AXA/Series 200 size was at its maximum range on a 12" lathe
so I figured that the next size up would be under less stress
on heavy cuts.
2) The Design of the wedge style pulls the holder against the
flats on either side of the dovetail, producing a more rigid
lock-up than the piston style, which pushes the holder *away*
from the body of the toolpost, producing lock-up only on the
angled sides of the dovetail, allowing for a bit more flex.
I later discovered another reason for preferring the wedge
style. That is that the angle through which the locking lever swings on
a wedge style is limited, while it shifts about 90 degrees towards the
chuck when you shift from the turning (side) dovetail to the
boring/facing dovetail (side towards the length of the workpiece). And
when there is no tool holder on the toolpost, it is free to turn a full
360 degrees, which can bring the handle into contact with the spinning
chuck. At least one poster here in the past encountered this very
phenomenon, resulting in the plastic ball grip on the end of the locking
lever turning into shrapnel when hit by the chuck's jaws.
Note that once you have used the quick-change toolpost, you will
not want to go back to the lantern style for most things -- nor will you
want to go to a turret toolpost. The reason for this is that each tool
gets its own toolholder, which has an adjustment nut which can be
locked in position so every time you drop the tool holder onto the
toolpost and lock it, it will be at the same height. Even when you are
not in a hurry, you may be reluctant to change tools to a more
appropriate one if you have to stop the spindle and re-adjust the height
of the tool. (The same reasoning applies to a quick-change gearbox for
threading and turning when contrasted to a change gears style, where you
must get your hands rather messy changing the gear train to get the
proper feed rate. (You *will* have to change to get the proper pitch
for cutting threads, which may make you postpone learning to cut
threads.)
With a lantern style, you have to tweak the height of the
cutting edge each time you replace it.
Yes, this was actually the main reason for me to consider an alternative to
the lamppost style.
As I said I do not do production work and I am not a trained machinist, I
sometimes 'design as I cut' and along with that goes a fair amount of
changing bits, a real pain with the old style holders and a source a great
possible error.
Uwe