[curtisturner]

A little info before I start
Milling on a Chevalier 1418 Mill
7.5 HP up to 10,000 RPM

I have some big chunks of 2" Thick Hot Rolled blank 8" X 18" torch cut from the steel house.
I have started with brand new 1/2" 4 flute End Mill ALTIN and TIALN and FIREX
1 of each of the above ended with dull or chipped end mills

I am trying to true up the blanks and cut a pocket in the blank.

I have tried various speeds and feeds to no avail.
I have tried the slow approach and the fast approach neither worked.
Is it simply that because they were CNC Blow Torched out they are now heat treated and to hard ?

Help

[Eldon_Joh]

did you read this thread?
http://www.cnczone.com/forums/genera...%20Bridgeport=

generally hard surface oxides will quickly dull the cutting tool unless you are taking a big enough bite to reach under the surface every flute, every turn continuously.
climb milling might be easier for the bit to cut through the surface but that depends. is it rust and oxides or is it big globs of super hard metal?
you may need to grind it all away.