Any Ideas About This Lathe?

What does mt3 mean then. Does it have to match exact specs? According to Littlemachinshop, an mt3 is supposed to be 3.19 inches long. If it is only 2.75 is it still an mt3? Of course that would throw off the .9380 major diameter. I think what I am asking is are the MT numbers accepted standards in all regards?
 
PaPa_Jack said:
What does mt3 mean then. Does it have to match exact specs? According to Littlemachinshop, an mt3 is supposed to be 3.19 inches long. If it is only 2.75 is it still an mt3? Of course that would throw off the .9380 major diameter. I think what I am asking is are the MT numbers accepted standards in all regards?
Click to expand...
The angle is of critical importance. The other dimensions can be approximate.
 
OK, I admit I may not be the sharpest knife in the drawer, but somebody is going to have to explain this to me.

Every bit of info I can find on a 9A says it is a 12 speed lathe. I can only figure out 6 speeds in forward and 6 in reverse, but that is not what the literature shows. How do I get 12 speeds out of this thing?
 
Hi Jack,

I suspect that maybe you have not found how to engage the backgear mechanism.

Some more pictures of your lathe drive system would help.
How many steps do you have in the head-stock pulleys?
How is it being driven? (ie. how many pulley steps in your drive train?)

From the manual I posted in post #19 of this thread:
upload_2016-9-5_8-42-13.png

upload_2016-9-5_8-42-13.png

(Sorry about the image sizes something wrong and it will not let me post full-size images!!!!)
(The second one is a "thumbnail view" that you should be able to click on to open bigger!)

It lists 6 direct speeds and 6 "back-gear" speeds.

Typically, backgear uses a shaft behind the headstock main shaft (thus the term "backgear"). When engaged it adds two more spur-gear speed reductions into the drive.
Typically need to do two things to enable it:
  1. dis-engage a small lock on the headstock pulleys that lock them to the headstock shaft
  2. move a lever that drives a cam that bring the gears on the back-gear shaft into mate with the headstock gears

I will try to locate some info for your specific lathe and post back with some pictures.

-brino

upload_2016-9-5_8-42-43.png
 
brino said:
Hi Jack,

Some more pictures of your lathe drive system would help.
How many steps do you have in the head-stock pulleys?
How is it being driven? (ie. how many pulley steps in your drive train?)

I suspect that maybe you have not found the back-gear mechanism?!?!?

From the manual I posted in post #19 of this thread:
View attachment 135299

View attachment 135299

(Sorry about the image sizes something wrong and it will not let me post full-size images!!!!)
(The second one is a "thumbnail view" that you should be able to click on to open bigger!)

It lists 6 direct speeds and 6 "back-gear" speeds.

Typically, it uses a shaft the site behind the headstock main shaft (thus the term "backgear").
You need to do two things to enable it:
  1. dis-engage a small lock on the headstock pulley that locks it to the headstock shaft
  2. move a lever that drives a cam that bring the gears on the back-gear shaft into mate with the headstock gears

I will try to locate some info for your specific lathe and post back with some pictures.

-brino
Click to expand...
It has a 3 step pulley. That gives 3 speeds plus 3 more with the back gear. That is only 6. Where are the other 6?
 
You have 3 speeds off the flat belt pulley.

With back gears, you have a low range for each of the flat belt pulley settings so 6 speeds.

Off the motor there is a two-setting pulley (HI-LO), so 2x the speeds mentioned above for a total of 12 speeds, although in the later years South Bend only recommend using back gears in the lowest flat belt setting while using High speed.

If you didn't get one with the lathe, it might be a good time to pickup a copy of "How to Run a Lathe" by South Bend. PDF scans are available on the internet and hard copies are cheap to find as they printed a LOT. I have the last version, the 56th edition, which was printed in 1968 onward and was the version that was available for my lathe. Also checkout the videos on Youtube from mrpete222. He has many, many shop videos online and goes over this basic stuff quite well.
 
Ahhh.....okay...you have found back-gear....that helps.

I have never seen one of these in person, but is there a way to shift belts on pulleys in the cabinet?

-brino
 
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There is a two step pulley on the motor, but the smaller of the two "V"s doesn't line up with the single pulley of the driven pulley. I would think it would wear badly, but I may be mistaken.

I do have a copy of the book you mention.
 
Post a clear picture of both pulleys. Perhaps someone changed the OEM pulleys.
 
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