I have a SB 10K that I am shopping for collets for. The machine was designed to use 6K collets but I have been told 3c will work. 3c tend to be less expensive and more plentiful (at lease on e-pay)
What's the difference? Would there be a particular benefit to springing for the 6K? Can I use both with the same closer?
No - 3C will not just work. The 3C are a different diameter and length. I'd say the person that told you this was confused about the 9" and 10K, and thought they were the same in collet respects. They are the same in many ways, but not with collets. The 10K lathe was designed to be a cheaper 10" lathe for school use, part the the cost-down design was an integrated 6K collet cup in the nose of the lathe. The 6K was larger than the 3C, 5/8" max round vs 1/2" max round.
I'd say dump the 6K collet closer on eBay. Take the cash & get a Bison 5C nose collets closer, a series 50 Jacobs Rubberflex collet closer or a Bison adjust true chuck. They will all work out to about $300 to $500 in total cost.
The 10K has a special secondary taper machined into
the spindle. This allows the 10K to use 6K collets
directly in the spindle without an adapter. These
collets are unique and are not interchangable with
the 3C collets.
The 3C's are smaller and have smaller threads on
the end. Therefore, the draw bars do not
The smaller 9" lathes have a Morse Taper #3 spindle
taper. They use an adapter in the spindle to allow
the 3C collets to be used.
But, it is possible to use 3C collets in the 10K.
The 10K spindle taper is a modified Morse Taper
#3 and will accept Morse Taper #3 tooling. So,
If you get the same set-up the 9" lathe used
(draw bar, adapter and collets), you can use it
in the 10K.
As mentioned, 3C collets are restricted on size.
SBL only offered 3C collets up to 1/2" (except pot
collets). Some after market makers offer them up
to 9/16". SBL offered 6K collets up to 5/8" and
some other makers offered them up to 11/16" (I
If you want more capacity, then a collet chuck would
be the way to go. Bison chucks are good. Jacobson
chucks are nice too but both are pricey. Another
possibility would be to make one from a kit. Metal
Lathe Accessories offer such a kit but it is a bit
advanced as projects go:
Metal Lathe Accessories
Just someting to think about. Good Luck!