Re: [CAD_CAM_EDM_DRO] Re: 60oz. stepper motors!

jepps5 wrote:

> I have a Harbor Frieght mini-mill. So your saying i could cut
> stainless if i take my time? How much do you feel I would be able
> to cut if I use a 1/4 inch endmill and how deep?

Well, not necessarily. Depending on the tool diameter, and the characteristics
of the steel, cutting speeds of 60-80 SFPM are recommended with HSS tools.
With a 1/4" HSS end mill, that comes to 1000 RPM. With a 2-flute end mill,
taking .0007" per tooth, a feed rate of 1.5 inch/minute would be reasonable
for light cuts. So, that sounds reasonable so far. Now, you will almost have
to run flood coolant, and if the workpiece suffers work hardening, the tool
will fail in a few seconds. The difference between overfeeding the tool and
allowing work hardening may be maddeningly narrow with this setup.

Really, you need to use carbide tools and very rigid machines for serious
cutting of bulk stainless workpieces. carbide, however, will triple your
feedrates, and therefor the horsepower required of both the spindle and
axis feeds.

It is usual practice to use no more than 1/2 the diameter of the tool
for width of cut, and no more than the full diameter for depth of cut.
For tough situations like this, you may have to back off of those numbers
significantly, especially where machine rigidity is lacking.

Jon