Hi!
Parting off should not be a hazardous procedure if all the factors of failure are know.
Most incidences are down to the parting tool not having enough side clearance for the swarf to go; two objects of mass cannot occupy the same space at the same time. A trick here is to whittle away a slot by removing the edges leaving space either side and then going straight down the middle for the parting action.
If a clean square cut is your goal then two important factors must be obtained, the cutting tool should be totally square with the longitudinal axis of the work and tool height should be dead center, assuming your ground profile on the parting tool are correct this should not be a hard procedure, again its down to clearance.
Another main culprit is backlash!. Yep hidden slack or lack of it will snatch your cross-slide forward digging the tool in which in turn sets off a sequence of events and ends up ugly quicker than a 50lb fat naked chicken running away from KFC. Limit this menace
But adjusting saddle cross-slide jib screws and don’t forget the top compound slide, plus another fiend could be the thrust feed screw bearing.
A parting tool should always be working meaning the feed of the tool should not lose contact with the work. The length of the parting tool should be kept to a minimum and should be as close to the chuck/collet as possible. chatter will be the evidence.
Another trick is if you want to part off anything over an inch slip it in back gear and take side cuts as I mentioned previously. If the material has a harsh scale on the surface remove this first giving the parting tool a chance to seat its self without damage.
All in all it is one of the most dangerous of machining set ups but its apart of our machining experience and should be mastered. When you are going to part off think through in detail your moves, how you will stand and how to lubricate while manually making the cut and if something screws up you what your actions will be.
Adhering to all of the above will limit your exposure to something drastically going wrong. don’t fear parting off be in control of it.
Hope this helps. Anthony.
