(note: sw-check spec sheet and correct)
S.B spindle nose diameters:
9 inch & 10K = 1.5 x 8tpi. Bore 0.938.
10L = 2.25 x 8tpi. Bore 1.629
11 inch = 1.625 x 8tpi. Bore .8750 Max collet size = 17/32 (last 11 inch "T" series)
13 inch = 1.875 x 8tpi. Bore 1.231 1.629.
14.5 inch = 2.25 x 6tpi. Collet 0.750. Bore 1.325.
14.5 inch = 2.375 x 6tpi. Collet 1.250. Bore 1.629.
16 inch = 2.375 x 6tpi. Bore 1.629.
Bob.
*****************
The last 11 inch lathes made were the T series, 1939-40, the spindle was carburized, hardened and ground
and had a hardness of 51-55 RC. The spindle ran in bronze bearings and was a top oiling headstock.
They had a three step cone pulley with a 1-1/2 inch belt. The hole through the spindle was 7/8 and the nose threads were 1-5/8 x 8 TPI. They used a No. 2 MT in the Headstock and Tailstock.
Steve Wells
***************

The spindle nose threads on the 10K is 1 1/2" x 8, just like the 9"(ABC).
The heavy 10" and 13" both have a small bore option (1 7/8" x 8 thread, 1.231" bore, 2C collets, 11/16" Max. capacity) and a large bore version (2 1/4" x 8 thread, 1.629" bore, 5C collets, 1" (or really 1 1/16") Max. capacity). On the 14 1/2", the collets for the small bore are in fact 3/4" max capacity, and they are 4C. The large bore uses 5C collets, with the same max capacity as above (stated as 1" on early lathes, 1 1/16" on later lathes, but actually the same collet). The 16" lathe collets are also 5C (1" or 1 1/16" max capacity).
Frank
*************

The K of the CLK indicates it shipped with a Taper Key Lock Spindle. My 16" has a CLC and shipped from the factory with a D1-4 Camlock Spindle
***********

The SB 14.5/16.5" lathe with the small spindle bore (3/4" maximum capacity, 1 1/8" hole through the spindle) used a 2 1/4" x 6 spindle thread, according to my literature. However I think this was a relatively rare lathe. I expect that most folks buying that large a swing lathe would pay a few extra bucks for the larger bore spindle supporting 5C collets (which used 2 3/8" x 6).
Frank
*********

The spindle you replace may have slightly different journal diameters, depending on the wear, manufacturing tolerance, etc. to the one you replace it with. This means that the shim packs under the bearing caps will probably need to be adjusted (either adding or subtracting shims as necessary for proper clearance). The Heavy Ten you have should have an "R" suffix in the unit code for your headstock. This is the smaller spindle Heavy Ten (1-7/8" x 8 t.p.i.). The "L" in 10L designates "Large Spindle" Heavy Ten (2-1/4" x 8 t.p.i.). The 10L is also listed for the other spindle types like L00, and 4D-1 Camlock. If your "new" (or should I say replacement) spindle already has its bearings with it, by all means use them. Just make sure that everything is clean and free of burrs. While you have the headstock apart, pull out your wicks and clean out the oil reservoirs, oil cups and the wicks. Use clean, fresh spindle oil when reassembling. I use Mobil Velocite #10 Spindle Oil. Spindle oil you use should comply with South Bend Lathe's recommendations of SUS 100 @ 100Deg. F. or ISO 22. There are several makes to choose from and can be had for about 10 buck a gallon (less shipping). This is about a lifetime supply for the average "hobby" lathe. I hope this information helps.
Webb Wyman
******************

Here's how SBL made the threaded spindles:
The material was a low carbon steel(8620 if I remember right)sawed to length. It was then drilled(trepaned) in a special machine made by South Bend. Then all the diameters turn turned approximatly .020" oversize except for the tread diameters (and the gear diameter on the 9/10K)These were left 1/4" oversize(thread protector). The I.D. taper was also bored with grind stock. The spindle was then carburized about .060" deep(not hardened yet). now the thread protecters were turned off and the recesses and keyways were put in(all the carbon that was added was removed from these areas to prevent them from getting hard). Back to heat treat to be hardened and straightened. Now a rough grind and then the threads were cut. The nose threads were cut with a thread mill and the take-up nut threads were single pointed. Finsh grind the O.D's and grind the I.D. taper,and last, but not least, super finish. Super finishing, kinda like honing, fine stones and lots of oil. The finish on 10,13,14 1/2, and 16" main bearing diameters were 2 to 4 RMS,cone diameters 8 to 10 RMS(I think). 9/10K were 8 to 10 RMS on both.
Ted Pflugner
****************

The South Bend Specs for the 10L "Heavy Ten" spindle is 0.602" Taper per foot as listed in "How To Run A Lathe" by South Bend Lathe. It is actually the same taper as Mores tape No. 3 which is .6023" Taper per foot. South Bend Lathe just rounded the dimensioned to three digits in this book. The large diameter at the opening is 1.629" If you have the 10R "Heavy Ten", the spindle has a Morse Taper No. 4 internal taper (i.e. .623" Taper per foot) and a large diameter at the opening of 1.231" .
Webb Wyman
******************

The small spindle Heavy Ten and 13 inch lathes have a Morse #4 taper (albeit short machine spindle type). You can use a Morse 4 to 3 reducer sleeve (get a soft one) and cut the smaller end off to suit. The larger spindle Heavy Ten and 13 inch lathes used a SBL proprietary taper that doesn't match anything but their sleeves (at least, nothing I have found).
Webb Wyman
******************

I think you'll find the 1 7/8" x 8 t.p.i. spindle (unit code "R") has a Morse Taper No. 4 spindle taper. 9" and 10K's have a Morse taper No. 3 spindle taper. The smaller spindle "Heavy Ten"s were made right along with the more popular 10L but the 10R was later dropped because of the poor sales it had. The "L" designated a "Large Spindle" or the 1" collet capacity (5C collets) and the "R" designated "Regular Spindle" or the 11/16" collet capacity (2S or 2A collets).
Webb Wyman
******************

The 10R has a 1+" bore (1" stock passes through without difficulty) and a 1-7/8" x 8 tpi. The collet size was 2A for these lathes. The 10L came with 2-1/4" x 8 tpi but there were two other possible optional spindle noses. That is, a Camlock D1-4 or a Long Taper L00 spindle noses. The Camlock D1-4 became the "standard" in the latter years of production and the 2-1/4" became an "optional" spindle. All could pass 1-3/8" stock through the spindle and used 5C collets.
Webb Wyman
******************

Not sure about the Jr but the spec in the files section shows the 9" to have a #3MT in the spindle. If the spindle hole is .938" at the end its most likely a #3MT, the following is if you want to nit pick... From the machinery handbook #3MT has socket opening of .938", depth is 3.25" and small end is .778" with a taper of .60235"/ft The #2MT is .700" socket, 2.5" depth (approximate) .572" small end and .59941"/ft taper. Acquire a #3MT dead center. Blue the taper shank and lightly insert it into the spindle with a turning motion. Remove it and look at the contact. The taper in the spindle will be shorter than the shank of the center. It will be around 2" which is the approximate depth of the spindle taper.
JP
********