# About South Bend 9 Spindles Sizes



## graham-xrf (Feb 8, 2021)

We are putting on the new belt, fitting up the underneath drive, and changing the wicks, so there is excuse to get a look at the spindle.
The condition looks OK, with no serious scoring, and the MT3 taper seems smooth and unhurt.




I tried measuring the bearing surface diameters, and the values seem unrelated to any of the fractions in inches one expects.
As carefully as I could using micrometer good to 0.001mm, I get..
Larger bearing   46.201mm => 1.8188 inches
Smaller bearing 35.200mm => 1.3858 inches

I tried checking against fractional inches. 0.8188" compares to 13/16" at 0.8125 which is 6.3 thousands too small.
Next nearest is 27/64" at 0.8438", which is closer, but I still think 0.025" is more than might be accounted for wear on something that has been on a film of oil all its life.
So I check 53/64" at 0.828125" , which is a whole 9 thousandths away.
The story is the same with the rear bearing. the fractional part 0.3858 comes closest to 25/64" at 0.390625" which is nearly 0.005" larger.

There seems no likely "nominal" size. Maybe they were just ground  and finished to within a range, and the headstock shimmed to suit, but this has me asking..
How much does an oil-film spindle "wear down", if at all?


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## benmychree (Feb 8, 2021)

What has not been said is how is the fit in the bearings; in the absence of any visable scoring on the bearing surfaces and a good fit, it would not seem to be a problem.


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## graham-xrf (Feb 8, 2021)

I am sure it is a good fit, and I was not saying there was a (function) problem. It is just that the fractional part of the measured dimension does not reconcile with any reasonable fraction of an inch that I could find.

To get a better idea of what this was about, I went after the spindle of the South Bend 9A, for a "comparison" to the 9C
The larger bearing measures very close to 1.8125", within a tenth or two, which is 1+13/16", and that is a fraction that makes sense.
The smaller bearing measures very close to 1.375", which would be 1+3/8", and that is a fraction that also makes sense.

The strange, oversized measures on the SB9C are not a problem, just surprisingly different. This lathe also happens to be the one without the serial number. I am totally pleased that the spindle is found in such good condition, and I have purchased a correct sized needle roller thrust bearing to replace the fibre washer at the back gear clamp nut.

This is as per the suggested modification by _*Halligan142*_ on YouTube with title "*South Bend Needle Bearing Mod*". He did this to limit the oil loss at the red fibre washer.


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## Manual Mac (Feb 8, 2021)

I’m trying to understand why a C spindle would not be the same as an A or B?
I understand other differences, but not the spindle.
Or are these differences  just on your own C&A models.
I did the fibre washer to needle bearing Mod to my 9C yrs ago, good mod IMO.


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## graham-xrf (Feb 8, 2021)

You ask exactly what I was after. Actually measuring the spindle bearning surfaces on one's lathe is something hardly anybody would do, even if they have taken the lathe apart to the extent of removing the spindle. Why would they?

My SB9C is very definitely a 9C, complete with the riveted on South Bend label, but it is a strange one, without a serial number. As I understand it, only lathes shipped to customers were given serial numbers. The lathes used at the South Bend Lathe Works were not given numbers, they might have been put together from any production stock handy at the time, and they were eventually sold off into the second hand market, or scrapped.

The SB9C is almost the lathe version of "One Piece at a Time", the Johnny Cash version of putting together a Cadillac! It's hard to set out exactly, but there are these "differences". The diameters of the tailstock quills are also different. They are not interchangeable. One can move the entire tailstock of the 9A to the 9C, and vice-versa, but you can't swap the quills. The springs around the headstock oiler felts are also "different".

I keep in mind that the lathe is in the UK, but I don't know it's exact history. How it came to be here, or whether it was manufactured here under licence for wartime production - who knows? The provenance of the 9A is more certain. It has a serial number, and was once used by the Royal Aircraft Establishment at Farnborough, Hampshire, because their brass asset number plaque is still on it. I just have to be very careful when I have two lathes, one in tiny bits, so I don't mix up stuff that will never fit!


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## benmychree (Feb 8, 2021)

Possibly in UK as a result of the "Lend Lease" program.


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## Manual Mac (Feb 8, 2021)

Is this the riveted tag u were referring to?
My (C?) ser#84029 left SB, April 8 1938. I know this because when I called South Bend Lathe Works around 1984 to inquire about change gears & a book, the fellow in customer service (Mr. R. Dieski) wanted my serial # and told me this.
I could be wrong but I think mine was before the 9A B or C designation  and simply called “workshop” or “toolmaker”
The guy I bought it from said it had come out of a high school, and he hauled it around with his tools as a mechanic on a race car crew.


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## graham-xrf (Feb 8, 2021)

Manual Mac said:


> Is this the riveted tag u were referring to?
> My (C?) ser#84029 left SB, April 8 1938. I know this because when I called South Bend Lathe Works around 1984 to inquire about change gears & a book, the fellow in customer service (Mr. R. Dieski) wanted my serial # and told me this.
> I could be wrong but I think mine was before the 9A B or C designation  and simply called “workshop” or “toolmaker”
> The guy I bought it from said it had come out of a high school, and he hauled it around with his tools as a mechanic on a race car crew.


That's interesting. Yes indeed, the riveted tag is exactly like that one in your picture!
There is a picture of it as acquired (for a song steal) $147.


It has the gears cover, tailstock shape, apron design, and other features that place it later than the Series "R" and 9" lathes shown in the 1938 catalog. The pictures in the 1947 and 1952 catalogs look much more like it. I date Catalog  9-F to *1947* because the first paragraph text says "The South Bend Lathe Works was established in 1906, and for 41 years has manufactured .. etc."



It shows the correct shape swing-out gears cover, and correct shape mounting foot at the tail end. Also, the style and mounting point of the on-off switch. The lathe, being underneath-driven, has a different shaped foot under the head end. The shiny spherical knob is to lift up the entire cone pulleys cover in one go, hinged at the back. The four screw holes below the knob were to fix the on-off switch box.

The previous owner had concocted a strange modified arrangement for the underneath drive. The long yoke is supposed to hang from the underside. Instead, he screwed it down onto a piece of wood on the floor, then turned the whole countershaft around to put the wheel on the "other" side. At first, I couldn't figure why the small end of the cone pulley was facing towards the wheel, until I found the correct pictures of the underneath drive

At some stage, they had "Workshop", Toolroom", and "Precision" lathes, differing only in equipment levels. The "Workshop" term was considered downmarket, and dropped by the end of WW2. They used the terms "Precision" and "Toolroom" interchangeably in the catalogs for the same lathes.

My lathe has got the "elbow" spindle oilers, which feed oil from underside by capillary spring-loaded dense wicks. This feature was introduced in 1938, which might date my lathe around 1938 - 1942 .

I think you are probably right, that this lathe was made just before the "A, B, C" designations were used.
Parts of Green Monster no longer look like when I first got it


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