I'm with Grant on this,

Is your tool post 'ROCK SOLID'.. If your cross slide has a compound on it
and you are not making threads.. get rid of it... make or buy a tool post
that mounts directly on the cross slide and is as big and massive as
possible.

I have an import 9x20 and the compound was a joke and was next to useless
for regular work, let alone cutting threads...
I replaced it with a pretty massive 4-way (about twice the size you'd expect
on a machine this small) and it works GREAT!
I can make better threads just plungeing in parallel on the cross slid than
I could with it.

--.- Dave

"Grant Erwin" wrote in message
...
manytoys wrote:

I am new to metalworking, and am struggling with my new lathe (9x20?)to
achieve decent surface finishes on steel parts. Currently I am working
with bright mild steel, but have just ordered some EN8, EN19 and SS304
to do comparative tests.
I do not have the ability to flood cool the job, I am considering
adapting to flood coolant system for use with soluble oil. Is this
worthwhile?

I am cutting with a Korloy insert tool, 50 m/min speed and 0.1 mm/rev
feed, which is conservative.

Any suggestions ??


I use a little lathe a lot too. Sometimes the parts come out like chrome,
sometimes they look like they'd been sandblasted. The difference is
usually the steel. You are obviously using British terminology -- in the
US we call BMS "drill rod" and it actually makes quite a difference what
kind of drill rod I turn. To get a good finish, I mean.

I really doubt it's your coolant.

I have never heard of Korloy. I'm not going to bother converting your
units to make sense to me. I'm assuming you've looked up the right speeds
and feeds. You can try sharpening a HSS bit and using that. Do your
roughing cuts first, and when you've gotten down to where your machine can
handle a rounder nose, use a tool with its actual tip stoned to about
1/32" radius (that's 0.79375 mm radius) and use a fine feed. Coolant IMO
mostly has two functions: it lengthens the amount of time a cutter stays
sharp, and it lowers the friction path for chips leaving the cut zone.
Both of these can affect finish somewhat, but not nearly as much as cutter
topology and correct speeds and feeds.

One more thing. Are you positive you aren't getting chatter? The modern
9x20 lathes are very light machines, and it's got to be tough controlling
chatter on them. If you look very closely at the turned surface under a
strong light, do you see what look like facets on a gemstone? If so, your
machine is chattering and you can work on trying to control that.

GWE