Need Boring Help

[ddickey]

Guys,
I have a boring job I offered to do for an old friend. Until I got the piece(s) in my hand I figured it would be straight forward operation. He says the material is Stainless. I'm not sure but these handles are really beautiful and well done, they look chromed to me. The job is to bore out the center bore from 12mm to 14mm. I notice there is a keyway in the bore, that's the first concern, the second is it looks to be a very hard material. The other operation is to drill and tap for a 4mm grub screw, difficulty there is the length of bit required to get past the handle.
Thoughts?

 

[mmcmdl]

Pulley tap . Boring won't be a problem . Edit . They most likely are electro polished and not chromed .

 

[ddickey]

Does that look like stainless to you?
What about the interrupted cut? Any concerns there?

 

[mmcmdl]

Cast stainless , yes . No problem on the interupted cut either . Choke up on your boring bar .

 

[ddickey]

Yep, gotcha.
Thanks

 

[mmcmdl]

Most all we do here is cast stainless and machined . Being they are " food grade " items , they require finishes 16 or below . Electro polishing makes them look like a mirror . For computer manufacturing customers , the finishes go down to 4 or 2 rms .

 

[ddickey]

Well I destroyed an insert (both sides) on the first handle. Detonated on my final cut. had to clean up the mess which cause me to go .4mm over my target of 12mm.

 

[BROCKWOOD]

"Need Boring Help" I'm no expert - but your help was entertaining to me. It isn't often that we see or hear of the oh-o's. Hope you get it figured out.

 

[mikey]

What kind of boring bar and insert are you using? What was the nose radius? Do you have any idea how you wiped out to sides of an insert?

I agree that the interrupted should not be a problem for carbide, brazed or inserted.

 

[ddickey]

A 1/4" Widia-Circle CCBI.
Insert is a CDHB 120605 so a .008" radius. TN7 is the grade.
No I don't. First cut or two went well. After a measurement that was way off I checked the insert and it was chipped. Changed to another insert (same type) that had one good side and that one really detonated, my final cut or .009". All cuts were ~.010 DOC, @~800rpm.