On Aug 11, 8:56 am, John Martin wrote:
On Aug 10, 11:06 am, Metalcutter wrote:





On Aug 10, 4:41 am, "Lloyd E. Sponenburgh"
wrote:

"Metalcutter" wrote in message

oups.com...
"You can't get a better finish on your part than what's ground into
your end mill."

.... heh! Where'd I hear something like THAT before ? G

He also said climb accross, conventional back. One: this gives you an
automatic finish pass.

.... yup... but there's a "yeahbut" in there. Yeah, but a lot of the cheap
machines built of grey-colored jello (and old, worn machines) have so much
flex and slop that conventional won't allow you to hold a dimension. So,
many rec. machinists end up climbing on all cuts, lest they over cut or
chatter the hell out of the surface.

Gotta have near-perfect rigidity to do it right.

LLoyd

I've always had good luck with it LLoyd.

But then my experience is fairly narrow and limited to Blue Hurcos and
an Index mill. :-)
I've never run BIG stuff.

The theory was: The climb cut would stress the tool and machine away
from the part and then when coming back on the same setting the tool
and machine would relax; and that small movement would allow for a
finish cut. Hand mill stuff.

As for CNC-ing I usually just run the same path again after the
roughing cut. That usually puts me within .001-.002 of where I want
to be.

Regards,

Stan-- Hide quoted text -

- Show quoted text -

You sure of that sequence? I've found that the reverse is usually
preferable.

You typically get better finishes from a light climb cut than from a
light conventional cut. With a conventional cut, the chip goes from
thin to thick, and the cutter may skid on the surface until there is
enough pressure and depth to get it to start taking a chip. With a
climb cut, the chip goes from thick to thin, and the cutter is cutting
from the start.

The problem with climb cutting is that it requires more machine
rigidity and less slop in the feed screws. And tight gibs. On my
horizontal mill, I can take a heavy conventional cut, but anything
more than a very light climb cut will try to pull the table along.
Not good.

So, for me, it's a heavy conventional cut followed by a light climb
cut.

Same thing with woodworking, but for somewhat different reasons. A
conventional cut tends to pull fibers up out of the surface, a climb
cut does not. But you don't want to try one with a router or shaper
unless it is a very light cut, unless the work is controlled by a
stock feeder.

Just my $.02 worth. Anyone else?

John Martin- Hide quoted text -

- Show quoted text -

It's worked for me John.

No my work if the table starts running ahead I just tighten the table
brake to just eliminate it.

Most of my equipment isn't all that worn though.

Thanks for the reply,

Stan-