On 2011-04-15, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
Ignoramus1116 fired this volley in
:

I would use something like 5/8" drill, drilling a 1/2" mild steel bar.

Oh... I thought at first you meant "high metal removal rate". You mean
"low BAR removal rate". Ig, the drill's bigger than the bar.

I meant, a 1/2" thick bar.

But that's just little stuff! G

The heaviest "drill hogging" work I've seen done on steel wasn't with
carbide, but with HSS with through-the-spindle cooling.

Dont have that.

Then there was some really heavy turning in Vallejo, with the lathe
taking out about a 3/8" deep chip at about 3/8" feed per revolution. Of
course, it wasn't really "big" work... just 12" or 16" prop shafts, but
I'll bet they get even heavier cuts on the _really_big_ shipyard lathes.

This is fun, I remember those 10 kW Russian lathes, with trepidation.



I saw one guy in Vietnam drill about .062" per revolution with a 3/4"
bit. He got away with it with no damage, but even with coolant, the
chips came out of the hole smokin' and blue. It was spectacular and
smelly, too, because he was using heavy sulfured oil for the
coolant/lubricant.

High tooth loads on carbide can be tricky, because it's so brittle. And
of course, it depends upon whether or not it's an indexable insert bit or
solid carbide (though I don't want to pay for new solid carbide in that
size).

I didn't check my tables, but I think 2500 RPM is a little slow for that
"small" a carbide bit at high feed rates. You'll have to talk to the
carbide guys... I use mostly HSS with a few indexable bits for boring and
finish work.

I just want to make a stunt video of a lot of chips being made.

For a short time, my mill can go up to 3000 RPM.

i