[tom bryant]

I'm running a job and just found out that my boring head will not go large enough. I have a narex boring head but it needs a kwik switch 200 arbor to fit my machine. Does anyone know of such an animal. If that is not possible can anyone tell me the best way to bore a brg. dia. with an end mill on a cnc supermax mill? .0004 is my tolerance 0n a 3.146 bore? Thanks!

[RICHARD ZASTROW]

I could be wrong but I don't think I'd want to attempt to circular interpolate a .0004" bearing bore tolerance. Think about roundness, size and bore taper due to cutter deflection. If this job has any volume to it, you should get a holder. If low volume or low repeat, I'd make up a boring bar that's adjustable with a screw and set it with a high accuracy (.00005") dial indicator.

Or get a relatively inexpensive Critereon boring head that will hold tolerance.

[RICHARD ZASTROW]

Tom, Does your narex have a 7/8 thread where the shank screws into the body? If so, there are some kwick switch 20 adaptors on the internet.

[tom bryant]

Richard,
The narex has a (4) four bolt pattern on the shank for a morse taper adapter. I've looked in the narex book and don't see a listing for the kwik switch shank but I thought I might not be the only one out there trying to do this. You think the circular interpolation is out because of roundness? I'm working with 6061-T6 al. and the bores are at the top of the peice only about .551 dp. There is only a dozen peices (this was a test run of 200) and this was to be my last operation. Bummer. I quess I'll have to indicate them in my lathe and bore them.

[HuFlungDung]

Tom,

Maybe you can get a quickswitch facemill holder, and make an adapter plate to bolt the narex to the facemill holder.

[RICHARD ZASTROW]

Tom, Assuming there is enough room between your spindle nose and the workpiece, I'd still make up an adaptor. How about a 4-bolt face to fit narex w/straight shank to fit collet chuck/kwick switch 200? If thats too much, how about a small indexable lathe tool attached like an adjustable fly cutter? I've done that buko times. Especialy for a 200 pc. job.

[tom bryant]

Thanks guys for the Ideas. In my befuddlement over the boring head not working I really lost sight of "getting the job done". Your right; there are many ways to accomplish the objective. I'm usually the guy saying "if you don't have what you need, use what you got"! Thanks for the reality check!
TOM