Boring Head Shank Mounting ???

[JoeLee]

I was cleaning up the R8 shank on a 3" boring head the other day. I had the head mounted in the lathe so I could polish some of the imperfections out of the taper and shank. I noticed right off as I was spinning it that the arbor was out of center and the end of the arbor was turning eccentrically. Almost like the arbor wasn't mounted square to the head. I know these arbors screw into the head but I'm wondering will this have any effect on the accuracy of a hole that is bored??? or doesn't it matter??
Will it cut an eccentric or tapered hole???

JL................

[Baz]

Big problem for a boring and facing head but insignificant I think for a plain borer.

[JoeLee]

I'm trying to visualize the positioning of the cutting insert in relation to the head as it turns. My guess is since it's stationary it's not going to matter.

JL...........

[Toolguy]

A single point cutter will run as true as the spindle bearings if held securely. Regardless of the connection between spindle and cutting edge, the cutting edge will turn in a perfect circle. The same thing applies to swinging a dial indicator in the spindle. The holder between spindle and indicator can be fairly convoluted, but the indicator will still swing a circle.

[JoeLee]

A single point cutter will run as true as the spindle bearings if held securely. Regardless of the connection between spindle and cutting edge, the cutting edge will turn in a perfect circle. The same thing applies to swinging a dial indicator in the spindle. The holder between spindle and indicator can be fairly convoluted, but the indicator will still swing a circle.

This is what I thought, thanks for the verification.

JL..............