Annealed 4140

[PixMan]

(01-21-2013, 07:55 AM)Mayhem Wrote:

(01-20-2013, 12:13 PM)PixMan Wrote: ...the finish you see is usually a result of short chipping in the turning operation. It's a necessary evil with a long cut, otherwise the long stringy chips can get wrapped around the part, the machine and/or the operator!

Ken - can you elaborate on what you mean by "short chipping" - is this the desirable little "9" shaped chips or something different. I get a similar finish in 1040 (feeding by hand). The only difference is I get some full circumference lines from the inevitable pause in hand cranking.

Yes Darren, I do mean that short chipping is to get those short tight 6's & 9's. I can't tell for sure which number they are!

In negative rake insert such as those Greg said he was using, there's a new chipbreaker design from Walter that is just fantastic in the gummy steels that don't like to break chips, such as 1018 and 1026 DOM tubing. It's their "MP3". I'm hoping they develop something like it in the positive rake screw-down inserts because it just kicks a**.



Those bumps just behind the cutting edge are taken from their inserts developed for machining titanium, another material that's really tough when it comes to breaking chips. The material coming off the cutting edge hits the bumps and gets curled, split and broken. Very cool.