# How Heavy Is Too Heavy For A Sbl 9" Chuck?



## griffin6.5 (Aug 20, 2016)

A bit of a novice question and excuse me if it has already been asked before (I researched and didn't find the info I am looking for).  Anyway I was curious and decided to weigh the 3-Jaw chuck that came with my South Bend 9A and found that it weighs approx. 30lbs. I am worried this may be too heavy for the spindle/spindle bearings. Am I right to worry about using a chuck of that weight. It is also the only chuck I have at the moment.

Thanks for any help


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## DoogieB (Aug 20, 2016)

What's the diameter?


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## griffin6.5 (Aug 20, 2016)

DoogieB said:


> What's the diameter?



It is a 6" chuck 


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## coffmajt (Aug 20, 2016)

I have a small 3 jaw and two different 4 jaws for my SB9 = the large 4 jaw is about 25 lb and has never caused me any issues.  As long as you keep good spindle oil in the cups you will be ok == Jack


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## Tony Wells (Aug 20, 2016)

Considering the cutting forces that are potentially there pushing and pulling on the spindle bearings, I'd say that 30 lbs is nowhere near the limit nor is an area of concern. I briefly looked for a max weight capacity for that machine, but was not successful in finding it. I'd find it hard to believe that the max workpiece weight would be anywhere near that low, and that, coupled with the forces of cutting should tell you that you're plenty safe with that chuck. Naturally, it will take a little longer to coast down without some braking system, but that's the tradeoff. Of course, any time you add to the bearing load, lubrication becomes even more important.


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## DoogieB (Aug 20, 2016)

That's definitely a stout 6" chuck!  I know the 6" Logan 4 Jaw I used on my 10K is noticeably heavily than the 5" Bison but I've never weighed either of them.

I dug around in a PDF of the 1967 South Bend catalog and found that they sold a chuck for the 9a/10K that was marked as weighing 33 pounds so I don't think you have anything to worry about.


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## griffin6.5 (Aug 20, 2016)

Thank you all very much for putting my nerves to rest.  30lbs seemed like a lot for a 6" chuck to me as well. I guess I won't worry about it too much then 


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## Mark_f (Aug 21, 2016)

The 3 jaw 6" chuck on my south bend 9 is the one that came with it when it was new ( in 1945) and it weighs around 34 pounds. It is very thick and heavy duty. The 4 jaw is much lighter.


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## dlane (Aug 21, 2016)

The lathe was designed to use that Chuck,


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