SOUTHbend 9 inch spindle bore ?

[754]

I don't have my SB9 nearby, I know they are considered 3/4 bore.,
Anyone know , closer than that ?
I have 20mm shafting I wanted to work on the ends of, if it fits in the chuck and spindle.
Probably wont, but figure someone may know.

[Mcruff]

I think mine measured .767, which is 1/64" larger than 3/4".

[Paul Alciatore]

I don't think that SB guaranteed anything other than the 3/4" advertised number. So, the actual diameter may easily have varied from one SB9 to another, particularly if they were made at different points in time.

I suggest that you try your 20mm shaft in the bore of your SB9.

[danlb]

The spindle bore is often associated with the taper that is used with it. Since the 9 inch uses an MT3 taper, the small end is likely to be 0.7780 as specified by that standard. 20mm is a touch larger.

We all understand that you can still use an MT3 taper that is shorter. This applies since a shorter taper will have a wider "small end".

For a while, it was common to use a reamer to enlarge the Seig C2 lathe bore. There was even a reamer being loaned via one of the online groups.

Without a reamer, you might be able to make the bore a touch larger via the judicious use of a boring bar.

Dan

[thaiguzzi]

My '69 Boxford (English version of the SB 9) is 13/16".