On May 9, 1:59*pm, Ignoramus11970 ignoramus11...@NOSPAM.
11970.invalid wrote:
Wild Bill, I tried cutting identical 12L14 steel rods with and without
coolant. The finish quality was much better with coolant.
...
i

Does "without coolant" mean completely dry?

I like to experiment with things like this. The biggest difference I
see is between absolutely no cutting lube and a little bit brushed on.
I'll start roughing down without any and see what the finish is.
Sometimes it's OK depending on the tool sharpness and geometry, feed,
speed and the material (often unknown scrap or hardware-store bolts
and rods). If the finish is rough I brush on a little cutting oil and
then watch. It may need more for each pass, or last a few before the
finish roughens. I think the best indicator is to add more when the
smoke fades out.

Decent HSS has never overheated on me without cutting oil. The
cheapest Enco blue-tube end mills dull quickly on steel at normal
cutting speed with or without oil, so I use my remaining stock of them
for aluminum while they're fresh, and then for questionable scrap
steel at a lower speed.

At work I generally machine plastic dry and aluminum either dry or
with whatever cutting oil is in the squirt bottle. The machinists and
engineers have their own preferences, some cut faster with flood
coolant and others don't to save cleanup time. The Bridgeport I've
been using doesn't have it and cleans up quickly with a shop vac. The
sticky CNC machines take a lot longer.

jsw