# Spindle Bore specification question

When spindle bore is specified as (say) 1", does that mean I can pass a typical piece of 1" stock through it?
The tolerance on standard stock is, say +/-0.002" so the actual hole would have to be a few thou bigger than nominal. Is it that way or is the bore size usually just the nominal size?
I'm talking bout Griz import lathes if it makes any difference.
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That depends on the machine. Usually it is slightly oversized with US made (or European made) machines -- except that the nominal diameter on the European machines will likely be a metric dimension, not inch.
If the dimension is too close, you could hit problems with runout in a 3-jaw chuck causing interference.

It probably does. Those were probably actually made to metric dimensions (Chinese and Taiwanese machines). The closest integer dimension to an inch is 25mm (lacking 0.4mm of full inch size), so it depends on just how oversized the spindle bore really is.
I have heard stories of spindles which were the nominal dimension at the ends, but which necked down in the middle. This would call for a gun drill driven by the carriage to open it up full length, letting the to-size part at the chuck end act as a pilot for the drill.
If the spindle won't quite clear your workpiece diameter and the workpiece is the nominal size of the spindle bore, I would just make a gun drill and take off those extra few thousandths. (Ask here if you don't know what a gun drill is.) However, I would *not* consider taking it up to the next size up. :-)
And, of course, this would almost certainly void your warranty.
And, BTW, what would be nicer is a bore of 1-3/8" 34.9mm, which means that 35mm would be the nearest integer size). The reason for this being a particularly desirable bore is that this will pass the drawbar for 5C collets, the most common (and thus the most affordable) size of collets.
So -- you have my thoughts on the matter.
Good Luck,         DoN.
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...
Looks like the 1" spindle bore is the 11" lathe for \$1700 and the next larger one with a 1-7/16" bore costs \$1000 more.
I like 5C a lot but perhaps not THAT much. Most of what I make from ground drill rod is 1/2" or less and a 3C collet would be enough. A collet isn't as useful for non-precision rolled stock, even if it fits. Out-of-round pieces can wobble.
Right now the lathe has a 4 jaw Sherline chuck on a 5C mount in it, holding a 6mm replacement choke shaft for my string trimmer that needed a rectangular cut for the lever on one end. The 5C chuck also fits in a spin index on the mill.
jsw
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[ ... ]

Ouch!
I was lucky that my 12x24" Clausing came with a lever style drawbar and nosepiece for 5C collets. (I actually just received a 5mm collet today -- ordered from MSC yesterday for a current project.)

Those Sherline chucks on 5C collet mount are nice. I've got one which Sherline put on eBay to boost the number of people who know about them.
I also got a small 3-jaw chuck on a similar mount -- but from a different maker, and the 5C drawbar threads are a bit oversized, making it a pain to get on and off the lathe. (Maybe I should try skimming the threads a bit in the lathe.)
Enjoy,         DoN.
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wrote:

Ive got an older, but rather good condition Hardinge TFB that Id let go for hummmm \$1800, give or take a little here and there Cuts VERY nicely, but doesnt do threading.
Cuts very nicely to .0002 <G>
Gunner
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