Newbie has some dumb (for anyone who knows about boring) questions. I am using an off-set boring head (APT) with "spoon type" cutters on a vertical mill to drill a number of odd size holes (eg .342", .543", etc), all between .3" and .75"; some shallow, some 1.3" deep, in carbon steel FS 1141 (heat treatment: normalize @1200F air cooled, hardened @ 1525F, oil quenched & drawn @ 700F) w/ Rockwell hardness @ A60-70. 1) Do these boring cutters plunge into the steel like a center-cutter?..., or do they need a pilot hole to enlarge?...would it be good practice to run a slightly smaller endmill down through the center anyways? 2) Would you suggest boring these holes out in one pass?...or more than one pass with increasing diameters? If so, what is a good incremental increase per pass? 3) The surface where the hole will go is irregular, ie. not flat: within the hole I want to bore the surface probably has up to three different levels, and I have parallel holes partly within the target hole. Does this present a problem for these standard boring cutters I am using? 4) Does anyone have any suggestions re: rpm and quill feed rates for what I'm describing? Without knowing any better, I would tend to use 300-400 rpm and feed by feel. 5) My mill (Bridgeport Series 1) has an auto quill feed which I have not used nor know much about. Should I be using that mechanism either automatically or manually?...or is the standard quill feed lever handle just as good?
As you can tell, I only know enough to be dangerous. Any advice would help me lower the danger factor. Thanks for looking!
BTW if any of you have helped me out in the set-up phase two weeks ago, I got this 25 year old machine up and running great! Shimming with steel plates and a rubber anti-vibration pad under each corner did the trick...and the VFD phase converter from that outfit in Brooklyn, NY for my single phase source seems just perfect; and Harold the tech was above and beyond: we got it running at 6:30 Friday nite over the cell phone while Harold was stuck in NYC traffic.
I am missing one of the 6 copper electric contacts in the motor reversing switch, just a ~3/8"x1+" piece of copper, no tools needed to remove or install. What's a good source for parts?