Boring Bar Use on 9x20 with CNC

[Cartierusm]

I've never used a CNC lathe, but from my previous posts you can guess I'm converting my HF 9x20. I'll need to bore out a Piece of aluminum to an ID of 1.5". I'll do a drilling operation up to 1". Then when I program to do the boring do I let the boring bar sit the full 7" I need to bore it? I mean do I let the full length of the bar hang out or is it not rigid enough and I should program stops to lengthen the bar as I go? Thanks.

[acondit]

The problem that you face is that if the bar isn't rigid enough to handle the full 7" extension, you will have problems with the bore changing size if you extend out in steps.

One solution might be to set up the piece to be bored on the cross-slide, then use a long boring bar chucked in the spindle and the other end supported by a live center in the tailstock. You would need to have the cutting tool at least 7" away from one end. Move the piece along with the saddle to bore it out. If you leave enough material on the outside, you can then set up the finished bore on centers and finish the outside to size. Dave Gingery used a similar method for boring the headstock on the Gingery lathe.

Alan

[Cartierusm]

It's a 3/4" boring bar with insert. I'll try it the regular way first. I'm going to build a steady rest that can handle 4" round stock to help with this.

[Runner4404spd]

if you take light enough cuts you should be fine. definitely make sure your using the Ak chip breaker inserts in whatever metal your cutting.

[Cartierusm]

The only inserts for it are triangle TPGB or TPGC which says it is a chip breaker. I'll look into it. thanks.