Well, that would make some sort of sense, as the long part of the jaw would be toward the Inside or the Outside of the chuck (i.e., referring to the chuck and not to the workpiece).

I never saw a reversible jaw 3-jaw chuck.  Whan do the teeth on the back of the jaw look like?

Robert Downs - Houston


In a message dated 02/04/2013 11:36:35 AM Central Standard Time, machineshop@... writes:

Robert,
I agree that, taken literally, they're misleading. However, I think that they originated with reversible-jaws chucks (i.e. chucks that can be flipped around and mounted the other way - generally swapping #2 and #3). When they are reversed, the inside will be out, therefore the name "outside jaws).

This is my hypothesis, no rigorous fact-checking behind it.

Paolo
Damascus, MD

On 02/04/2013 12:18 PM, wa5cab@... wrote:

  Does anyone have any idea why the two sets of jaws normally supplied with solid-jaw 3-jaw chucks are commonly called "Inside" and "Outside"?  Both sets are used for both functions, depending primarily on the OD or ID of the workpiece.  I don't know what else one might call them but those names would seem to be misleading.

Robert Downs - Houston