South Bend 9 " Lathes A,B,C

What is the differance in 9" South Bend Lathes Model A, B, C ?

Hi There,

In the 9 inch lathes the three models are A, B, and C and are as follows:

The Model A has:

Quick Change Gear Box,
Power Cross Feed,
Friction Clutch and Half Nuts Apron.

The Model B has:

Separate Change Gears,
Power Cross Feed,
Friction Clutch and Half Nuts Apron.

The Model C has:

Separate Change Gears,
Half Nuts Apron.

The Model A is the most desirable and usually brings the higher prices.

I hope this helps. Good Luck!

-Blue Chips-
Webb

Thank You Webb

I have the Model A with a 4 1/2 foot bed.
I have seen posts about the models B&C and didn't know what the differance was from my model A.
So when looking for used parts for my model A I should stay away from model B&C models...Correct?

Jesse

9" South Bends also came as a Toolroom model. This was Model A with the following additions:

precision lead screw
handwheel collet closer
collet rack
taper attachment
thread dial
thread stop
micrometer carriage stop
large face plate.

Interesting note. When I got my 10L last year, I called LeBlond and got a copy of the serial card. It was listed as a toolroom model less a taper attachment. I didn't realize you could pick and choose like that.
Bob

Hi There,

Most of the parts for on a particular series lathe (like the 9 inch horizontal drive) are the same between the models A, B and C. Just the parts pertaining to the Gear Box, Apron and Cross Feed are different. For example, The Model A Gear Box and Lead Screw are unique to that model. The Friction Clutch Apron is the same on models A and B and so is the CDross Feed Screw, but the Lead Screw on the Model B is unique. The Change Gears are the same between models B and C but their Aprons, Cross Feed and Lead Screws are not.

If you haven't picked up a parts manual for your lathe, get one. You can get them from Leblond Lathe (owners of South Bend Lathe) and copies are sold on eBay. Also, there are copies on-line. Check out the link below:

http://www.zetagraphics.com/shop/sbparts/sbparts.html

As to accessories for your lathe, they are the same for all models within a particular series. When looking for parts or accessories for your lathe, check the unit code. All sub-assemblies and most accessories will have a unit code stamped on them. For example, your compound will have a unit code stamped in the T-slot under the tool post. It will look something like "C 100 N." Your apron will have a unit code something like "A 100 N" or "A 101 NK" on the front.

The unit code is made up of three parts: The prefix letter or letters identify the subassembly (C - Compound, A - Apron, etc.). The body number of the code identifies the version of the subassembly. The first number is the major design version and the last two numbers are minor version changes. (e.g. 100 - first design, 101 - first design, first version change, etc.). The suffix letter or letters identify what lathe series the subassembly will fit. This is the most important information to remember! The suffixes are as follows:

N - 9 Inch,
K - 10 K,
R - Heavy Ten,
L - Heavy Ten (Large Spindle),
T - Thirteen Inch,
F - 14.5 Inch,
H - 16 Inch.

Now, some subassemblies and accessories are used on more than one series lathe. The 9 inch and the 10K lathes share many of the same parts and assemblies. Therefore, the apron (on later models made after the introduction of the 10K) will be marked with a two letter suffix code (i.e. "A 101 NK"). These suffix codes are used in part numbers also (except "general hardware" parts) . For example, the cover plate used on the micrometer carriage stop is part number: PT1209NT1. This breaks down to: "PT" - Part (Assemblies start "AS"), "1209" - The Number, "NT" - Fits lathes 9 inch Through 13 inch, "1" - First version. Sometimes, you can see similar numbers cast into some parts as well. These suffix codes are very useful when checking used parts for compatibility with you lathe.

I hope this information is helpful, Good Luck!
-Blue Chips-
Webb

WOW !!!!!...6 lathes & no south bend ,so far ,.... but that post was pure GOLD ...already printed out & in the binder

tnx Webb

best wishes
docn8as

Bob-O mentioned a "precision lead screw" as one of the upgrades that turned a Model A into a "Toolroom model".

Anyone know what it is that makes a precision lead screw different than the normal USA 8 tpi acme threaded leadscrew?

I've read implications in a few places that it was a different pitch thread on the leadscrew, but it's always sketchy info at best.

I've never seen a different pitch leadscrew for sale either in person or on ebay. I've never seen matching half nuts either for that matter. I figure that if there were other pitch lead screws in use out there, SOMEONE would be talking about how to fix or replace them.

The reason I ask is that I've got a leadscrew in the workshop that is the right size and shape for a SB model A, but the thread pitch is way tighter than 8 tpi. I don't know if it was a one-off shop made piece, an unusual factory option, or not South Bend at all!

Thanks for the space!! Itemsonsale

Itemsonsale,
Regarding South Bends precision lead screw, the parts manual shows different part numbers for regular versus precision lead screws. IMO, it was probably processing and tolerancing differences that made them unique. If the pitch was different, the gearing would need to be different too, requiring separate gear boxes. Just my opinion after looking at the parts lists.
Bob

Hi Bob,

Thanks for checking. They don't happen to list any different versions of the half nuts do they?

I don't remember offhand where I heard that they used different pitches on the leadscrews. I'll try to see if I can dig that up again.

Anyone else heard of such a thing?

Anyone ever seen 16 tpi half nuts to go along with???

Hi There,

Generally, the "precision" lead screws were hardened and ground as opposed to just machined. This makes the part smoother functioning and longer lasting! They used the same half nuts.

-Blue Chips-
Webb

Itemsonsale,

Is your lead screw perhaps metric? My 1941 catalog shows a metric lead screw available along with metric cross feed and compound screws with metric collars.

Stu Miller

Metric? Now that's an option that I hadn't considered... Thanks for the idea Stu. I'll take some measurements tomorrow when I get a chance and see what I come up with.

Your parts list wouldn't happen to mention the thread pitches of the metric options? How about metric half nuts to go along with the metric lead screw?

Itemsonsale

Itemsonsale,

According to my 1941 catalog, the metric lead screw pitch is 3.0mm. I also checked my parts list. It is undated, but it does give the price of an exchange headstock for a SB9 as $57, so that should give you some idea as to age. It shows the metric cross and compound screws and collars, but doesn't mention metric lead screws and half nuts. Incidently, the price for half nuts was $4.90.

Just for general interest, the cross and compound screw pitch is 2.5mm.

On the subject of precision lead screws raised earlier, the parts list shows them as available only for the model A.

Stu Miller

Thanks again Stu. I measured the mystery leadscrew and it's 16 tpi, so the metric thing unfortunately didn't pan out.

I have absolutely no idea what this thing is for... It's the size and shape of a SB 9" Model A leadscrew for a 3 or 3 1/2 foot bed, but it's got 16 tpi acme threads.

It sure doesn't look like a one-off that someone gnawed acme threads into. It looks very well made.

Anyone seen any other lathe that uses a 3/4" diameter leadscrew with 16 tpi?

Itemsonsale

<edit> PS - BTW, the priced in your book are excellent. I'll take a whole bunch of half nuts at that price!!

Hi Web, I have a 9" Model A and am needing a tool post ring and tool post wedge. Have any ideas where I could find something like that. Restoration is almost complete but can't play without it.

Excellent information...I should print myself.

It might be worth mentioning that Model B 9" lathes can be upgraded to Model A by adding a QCGB
and correct length lead screw. Most Model B's (that I've seen) already have 3 holes in the bed to
accompany such a change. (I am currently upgrading a B to an A, and currently working on a bench).

The Model C's generally do not have a third hole, and must be drilled, along with a change of the banjo and apron for starters.

But you prob already know this.

PMc

View attachment 317936

Gary Rummery said:

Hi Web, I have a 9" Model A and am needing a tool post ring and tool post wedge. Have any ideas where I could find something like that. Restoration is almost complete but can't play without it.

Click to expand...

Grizzly has them brand new. They own the rights to the SB name nowadays. Link: Rocker Type Tool Post For Lathe at Grizzly.com

pavt said:

Grizzly has them brand new. They own the rights to the SB name nowadays. Link: Rocker Type Tool Post For Lathe at Grizzly.com

Click to expand...

i got to tell you ya it would probably work but yuk the old stuff had lines to it all this new stuff all looks like a rectangular box the new south bend would be better off calling themself mama dumpling lathe works the only good thing is they are a source of some replacement parts that mite work

why would you want the old rocker system. just get a quick change AXA tool post. Or a MULTI FIX.

Woodchuck does bring up a valid point IF you think you are inclined to switch to a QCTP at some
point in time. I personally have not taken that step, but I do like the ENCO style tool holders.
Since I prefer to grind my own HSS bits, I tend to use my rocker style on occasions. (As nice
as the Enco's are, you can only shim on the bottom to raise the bit.)

Having a rocker style is a good "go to" holder when all else fails. Quick to set and adjust, that's for sure.
I don't particularly have a problem with the new fangled holder on Grizzley site; I'm sure it will work
fine. I am surprised that there aren't more originals on that auction site. Guess people are holding onto them.
In the end, no one that visits your shop will know that the rocker is not "original", and I wouldn't let that
keep me from making chips. And besides, who cares?! You can always sell it if you find what you are looking for
down the road.

Like 1yesca would do, just throw in in your tool box and shake vigorously; it will look authentic in short time.
(Just kidding )

PMc

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