Model A Chuck Size?

So what's the objection? Legions of people use 6" chucks on South bend 9" lathe, in fact I don't think I've seen one with a 5" chuck before. The jaws clear the ways when they're at their maximum diameter, the weight is trivial relative to the size of work piece the lathe can work and then only downside I can think of is that you'll lose a wee bit of bend length relative to a smaller chuck.

Saying an 8" chuck would fit is asinine, it clearly wouldn't as the jaws won't clear. Are you simply being dogmatic due to a short passage in HTRAL?
 
Here is a SB9 with a 5” 3 jaw chuck (as SB recommends), now you’ve seen one.
 

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Well that's a sucky response. If you have an objection to my reasoning, point it out. It's not "my way", it's the way of nearly everyone that has an SB9. Besides the OP can stick whatever they like in their lathe, no skin off my back. They can put one of those miniature 2" chucks on if they want..
 
Wow, that's the first. Here's one with a 6", now you've seen one
IMG20221217222825.jpg
And with the jaws about to fall off the scroll
IMG20221217222910.jpg
 
So I'm guessing your reasoning against 6" chucks on an sb9 is that you have a 5" and the law says you have to have a 5" so a 5" is all you can have? Did I get that right?
 
A sucky response? Please…
a 6” 3jaw weighs 20yrs.
A 5” 3jaw weighs 11 lbs.
do the math.
do you want an extra 9 lbs on a plain bearing cast iron spindle boss all the time?
Clearly SB doesn’t, so they recommend 5” for a 3 jaw chuck.
possibly you know better.
BTW I have a 2” 3jaw off my DB200 that I sometimes use on my SB9.
Cheers
 
Ah there you go, a reasoned response at last. Fair enough, though I think your grasp of the load bearing capacity of a 1-1/2 to 2" by 1-1/2" plain bearing is a little lacking. A reasonably sized piece of cold rolled steel would easily exceed the difference in chuck weight between the two sizes, yet is well within the turning capacity of the lathe.

Good reasons for a smaller chuck are quicker acceleration, ability to hold really small stock and ability to extend over the cross slide (though that would take an odd set up to be useful). Also hoofing it on and off would be easier. Wearing out the bearings is not.
 
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