Subject: Re: South Bend Spindles

From: [email-masked] (-F.KERFOOT)
Date: Mon, 6 Feb 1995 16:12:36 GMT

In article <[email-masked]>,
John Angus <[email-masked]> wrote:
>J. Kimberlin ([email-masked]) wrote:
>: In article <[email-masked]> [email-masked] (GAshmore) writes:
>: >Boy! Am I confused.  I have a 10K built in 1955.  A MT#3 fits perfectly in
>: >the spindle.   There is no adaptor in the spindle.  It is just a plain old
>: >MT#3 with a flaired end to fit the collets.   But I looked it up in all my
>: >SB liturature and it says MT#2 spindle????  My lathe came with a full set
>: >of collets but I have no idea whether they are C5 or C3.  I need to order
>: >some soft collets but now I don't know what to order.  
>
>Because of all the confusion in this thread, I got out my exploded view
>parts list of South Bend spindles. It turns out that there were both
>#2 morse for 11/16 collets and #3 morse for 1-1/16 collets sleeves to
>fit the spindles.
>
>I think this means that there IS an adapter in your spindle.
>...
>I hope this subtracts from rather than adds to the confusion.

Mea culpa. I think I got a lot of the mis-information started, with
my comment that the 9" SB had a different taper dimension than that
listed in Machinery's Handbook for a #3 Morse. Imagine my surprise
when I looked again over the weekend, and the taper dimension for a
#3 Morse taper had mysteriously changed to 0.602", the same as SB
specifies for the spindle taper of a 9" lathe. So, I obviously
screwed up when I looked it up last week. I am therefore now convinced
that the 9" SB (and BTW, the 10K) have a #3 Morse taper directly
on the inside of the spindle. The sometimes specified #2 Morse is
with the addition of an adaptor. A 3C collet will in fact fit in
a #3 Morse taper, with room for the addition of a suitable collet
closing sleeve. In response to Jerry's other question, his 9" SB
almost certianly uses 3C collets. The hole is not big enough for a 5C.
The collets you have should say "3" or "3C" on them, depending on
their age, as well as a manufacturer and a size.

The other SB lathes which hold larger collets are more interesting.
They also have the same specified spindle taper dimension of 0.602"
(with 1 exception), even though the larger Morse tapers have a different
specified taper. It looks like SB chose to use the same taper on
everything, while the Morse standard went to different taper dimensions
for each size. I wonder who came first. As noted by another poster, 
I'm not surprised that other suppliers than South Bend chose a standard
Morse taper like #5 as the basic spindle taper, rather than SB's
non-standard taper.

In response to John's comments, it sounds like your literature is for
a 13" SB, and in fact refers to the size of the taper of the center
to be used in the headstock with the addition of an adapter. For the
10" SB, (not the 10K, which is a variation on the 9" SB), there were
two collet options. Most were purchased with 5C (i.e. 1 1/16") collets,
but they could be had with 11/16" max. collets as a special order
(I think they were 4C collets). In the 10", both of these 2 options
called for a #2 Morse center in the headstock, although they required
different adapters to do this, since the basic spindle tapers were
different. Most of this also applies to the 13". Most had 5C (1 1/16")
collets, but 11/16" max. collets could be ordered as an option.
My literature says that the 13" with 5C collets used a #3 Morse center
in the headstock (with an adapter). I'm not sure about the 13" with
11/16" collets, but from your literature it sounds like it must have
used a #2 Morse, again with an adapter.

Is everyone confused enough yet?

Frank Kerfoot
[email-masked]