Rich, I wouldn't say that the speeds are totaly inappropriate for the
7x's, but I would use them as a general guide. For most steels, I
generally run at a lower speed, typically between 9:00 and 11:00 on
the dial (in low range), and with aluminium, I run at higher speeds,
typically 10:00 to 1:00 on the dial. The finish is more of a
function of how deep you're cutting and the type of toolbit you're
using. I use predominatly carbide (brazed/cemented & inserts) and
get a pretty decent finish. On the roughing cuts, I'll go anywhere
from about .015 to .020 on steel, as much as .050 on Al. I let the
machine tell me when I'm a little too aggressive, usually groans or
chatters if I'm taking too much (or stalls when it hogs in)... For
my finishing cuts, I generally only go .001 - .002 deep and speed up
the machine (around 11:00 to 01:00 for steel, 01:00 to 05:00 for Al)
and manually advance the carriage. I always use some form of lube,
usually "tapmagic", applied with a small brush to the rotating piece
and I'm usually pretty happy with the result. I keep some strips of
400 grit wet/dry close by to polish a little while rotating also (be
careful it doesn't pull you in). The finish is generally better also
if you use a more blunt or rounded radius on the toolbit with light
cuts rather than a sharp pointed one, in my experience.
Ed
--- In 7x12minilathe@..., Richard Kleinhenz
<woodnpen@o...> wrote:
I understand that cutting speeds published in the books are
generally used for large machines, and that they are totally
inappropriate for our 'toys'. (I have a 7x12). We should go by what
feels right.
I am looking for a little guidance here. Say I machine 3/8" or
1/2" 1018 steel. Where should I be approximately? I have an
inexpensive indexable toolset from LMS. The surfaces I get are
nothing to write home about... Can anyone with some experience steer
me in the right direction? Should I always apply cutting oil? How
much to remove in a pass? What speed? I am on the low range. What
dial setting appr.? It seems easier to take a heftier cut than a
small cut... something seems wrong ;-) Is there something like a
lower limit for a lathe cut?
I get by, because I don't need a good finish on these simple
bushings I make, but I sure would like to do it better eventually.
Thanks for any pointers!
--
Regards,
Rich
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Richard Kleinhenz
mailto:woodnpen@o...
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