Machining 4140

[Cross Slide]

(07-04-2020, 08:42 PM)Dr Stan Wrote: You're probably not going to be able to take anymore than .050" DOC (Depth of Cut) and possibly only about half that amount.  Do you have access to another lathe that can take a deeper DOC?  If so rough it out there.  BTW, you'll want to finish it mounted on your spindle to make it as true as possible to your machine.  Also use a center punch to show its mounting position.  I always make 4 little center punch marks to show alignment/location on the spindle nose.

Definitely can’t pull off .050 with my lathe. But I was able to do .030. I’m very happy with the finish I got. I will definitely be finishing it up attached to the spindle. I currently have one side faced and the bore done so it will fit snug on the spindle register. Last weekend I made a gauge that is the exact size as the spindle register, so I had something to test fit without needing to pull my 4 jaw chuck off to test fit it. Next I will fit Put it on my mill and set my DRO for a bolt circle and drill and tap the holes. Then bolt it to the spindle an machine the second side to fit the collet chuck. I will definitely mark it’s location to the spindle. My 3 jaw chuck has a 0 on the chuck and the backing plate that correspond to a 0 on the spindle. 
Trevor