[FAMOUSX1]

Can anyone recommend some techniques on cutting this stuff on a lathe. it take forever to get this stuff to look somewhat decent on the finishing pass. thanks

[HuFlungDung]

What kind of tooling are you using currently?

[Pxsi]

I have been struggling with 4130 too; I think my problem is that my machine is not rigid enough. This stuff needs a really stiff lathe.

[ajl6549]

One problem with 4130 is it is not very consistant, chemicaly that is. By that I mean the chemical tolerences are fairly wide open. This means that what works once may not work every time. That having been said, what are you trying to do, finish wise? Somtimes a finish may look...bad, but may actually be ok. Like it may have visual inconsistencies but may fit a given finish tol. zone (i.e. a 125)

[SeaSchell]

Alot of the finish looking bad is not a heavy enough finish pass. Also look into cermet inserts these things will take a .001 finish pas & make it look beautiful. I have a small selection of Kyrocera inserts from yearts ago that I still hoard like gold for their finish capabilities.

[FAMOUSX1]

well mainly im having problems with the porting on a lathe. and i beleive im using iscar inserts for the groves and threads. the boring bars just arent doing a good job of finishing. if i go any slower i will be going backwards

[tobyaxis]

well mainly im having problems with the porting on a lathe. and i beleive im using iscar inserts for the groves and threads. the boring bars just arent doing a good job of finishing. if i go any slower i will be going backwards

Try Trigon Style inserts with a "Circle Tool" Boring bar. The largest tool nose radius your part geometry will allow. MSC sells Circle Brand boring bars with a Solid Carbide Shank with a through Coolant hole. I use Cermit inserts at 700 to 900 SFPM .005 IPR in 4140 and the parts came out with a mirror finish with no visable tears.

www.mscdirect.com

[FAMOUSX1]

for the ports i dont use an insert. i use a solid boring bar for a -6 and down anyway. if im doing a -8 or up i use inserts and it come out fine. but at the moment im doing a 6, so i manually sharpen the boring bar to the radius needed usually a 12. if i use inserts on smaller part they seem to chip easily

[tobyaxis]

The chipping could be happening for a few reasons. Chips at the bottom, feeds and speeds, wrong grade of Cermit insert, incorrect boring bar or insert geometry.

That material is gummy and hard. It is difficult to get the chips to break without the correct tool or cutting geometry.

Can you post some part and boring bar geometry?