Subject: South Bend Spindle Bore

From: [email-masked] (Mark Will)
Date: Tue, 27 Sep 1994 17:33:50

I have a 9" South Bend lathe that I would like to be able to do turning
between centers.  What type of bore does the spindle of my lathe have?
Is it a standard taper?  If so is there an adapter available to allow me
to use my #2 morse taper centers in the spindle.  I have the dog plate, dogs,
and a couple of #2 taper dead centers.  The #2 fits the tailstock but the 
spindle bore is much larger.

Mark

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From: [email-masked] (Joe Landau)
Date: Wed, 28 Sep 1994 05:15:28 GMT

>spindle bore is much larger.
Lindsay's reprinted 1934 SB catalog shows #2 morse taper for all the 9"
lathes.  Maybe yours is a #3.  You can buy #3 to #2 adapters--in fact, I
think I have a spare, but if I do it's in poor condition, and of questionable
value.

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From: [email-masked] (James Kirkpatrick)
Date: 28 Sep 94 09:21:09 MDT

|>In article <[email-masked]>,
   Mark Will ([email-masked]) writes:
|>>I have a 9" South Bend lathe that I would like to be able to do turning
|>>between centers.  What type of bore does the spindle of my lathe have?
|>>Is it a standard taper?  If so is there an adapter available to allow me
|>>to use my #2 morse taper centers in the spindle.  I have the dog plate, dogs,
|>>and a couple of #2 taper dead centers.  The #2 fits the tailstock but the 
|>>spindle bore is much larger.

Check out an assumption I've made for no good reason:  The spindle taper
is usually one step larger than the tailstock taper.  For example, if
the tailstock is MT2 then the spindle/headstock is MT3.  Note that there
is no overlap in Morse Taper sizes.  Extracting from the next issue
of the FAQ:

      Morse:  Very common in lathe spindles and tailstocks.  Different
      standard sizes exist, such as MT1, MT2, and so on.  The actual
      taper varies from one size to the next.  Some examples:
         MT0   small=.252 inch, large=.3561 inch, taper=.052050 in/ft
         MT1   small=.369 inch, large=.4750 inch, taper=.049882 in/ft
         MT2   small=.572 inch, large=.7000 inch, taper=.049951 in/ft
         MT3   small=.778 inch, large=.9380 inch, taper=.050196 in/ft
         MT4, MT 4 1/2, MT5-MT7: see references.
      These values are for the "business" part of the taper, and exclude
      whatever the taper is attached to, such as a drill or a center,
      and also excludes the tang, if any.

Maybe with this, and assuming Morse, you can take a quick measurement
and determine the taper.

Jim

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From: [email-masked] (Ed Richley)
Date: 28 Sep 1994 14:57:35 GMT

>think I have a spare, but if I do it's in poor condition, and of questionable

This is interesting....

Evidently on some lathes, its a special "South Bend" taper. Adapters
are available for MT2 and MT3, and they aren't terribly expensive (at
least, the ones I got for my heavy 10 weren't terrible) from SBL.

My copy of "How to Ruin a Lathe" lists the dimensions of this taper. For
a 9 inch lathe:

Opening diameter: .938
Taper per foot:   .602
Spindle ID:       .750

Now, on a different page, they list Morse tapers. Oddly enough, an MT3
is:

Diameter of plug at small end:   .778
Diameter at end of socket:       .938
Taper per foot:                  .6023

In other words, it's the same, and you'e in luck. MT3 to MT2 adapters
are very available, and are really inexpensive. You just want to make
sure that you don't do anything to bung up that spindle. 

It looks as if they provided several options on this spindle. The 10 inch
was available with (apparently) an MT4, or the one that I have. 9 inch
and 10K seem to have the MT3. The larger lathes (13 to 24) have my spindle.
Why they didn't just use MT5 for these, I'll probably never know.

Ed

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From: [email-masked] (Ed Richley)
Date: 29 Sep 1994 01:36:54 GMT

>         MT4, MT 4 1/2, MT5-MT7: see references.

Those "taper" values should be checked.....they just don't look right.
Maybe off by a factor of 12?

Ed

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From: [email-masked] (-F.KERFOOT)
Date: Thu, 29 Sep 1994 12:44:31 GMT

In article <[email-masked]>,
James Kirkpatrick <[email-masked]> wrote:
>...

I don't believe your assumption holds in general, although I believe that
it happens to be correct for the 9" (and 10K) South Bend, which have
#2 Morse tailstocks and #3 Morse spindles. My "heavy" 10" SB, as another
poster with the same lathe noted, still has a #2 tailstock, but a
significantly larger spindle bore. I am reasonably sure it is #5 Morse,
but most work is done with the 5C collet adapter, which has the
appropriate OD taper for the spindle ID. I believe that to use a
head end center, my lathe came with a #5-#3 Morse adapter, and then
a #3-#2 adapter. I have also used other lathes in this size class
(i.e. a 11" Sheldon) with #2 Morse tailstock and a spindle suitable
for 5C collets (which is significantly bigger than #3 Morse). Your
assumption might work for lathes with spindle bores suitable for
various 3 series collets, where the through hole is typically in
the 13/16" range (versus perhaps 1 3/8" for a lathe using 5C collets).

Frank Kerfoot
[email-masked]

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From: [email-masked] (James Kirkpatrick)
Date: 29 Sep 94 09:51:24 MDT

In article <[email-masked]>,
[email-masked] (Ed Richley) writes:

|>[email-masked] (James Kirkpatrick) writes:
|>
|>>         MT0   small=.252 inch, large=.3561 inch, taper=.052050 in/ft
|>>         MT1   small=.369 inch, large=.4750 inch, taper=.049882 in/ft
|>>         MT2   small=.572 inch, large=.7000 inch, taper=.049951 in/ft
|>>         MT3   small=.778 inch, large=.9380 inch, taper=.050196 in/ft
|>>         MT4, MT 4 1/2, MT5-MT7: see references.
|>
|>Those "taper" values should be checked.....they just don't look right.
|>Maybe off by a factor of 12?

Exactly.  Though I wrote in/ft, I copied down the in/in figures from
the Machinists' Ready Reference!  I'll correct these before posting the
next FAQ (hmm, I had better hurry! :-).

Jim