"I have a part that requires internal gripping. What are my options?"
"There are two options--the "Master Expanding Collet" and the "Sure-Grip Collet-Style Expanding Collet". Both of these can be used in a 5C or 16C spindle. The Master Expanding Collet uses interchangeable pads which can be removed and stored. This unit is opened with a draw plug that actuates the collet in the front. It is mainly for light duty machining.
The Sure-Grip Collet-Style Expanding Collet system will also work. The collets are parallel opening and have a range of .125" to 4". This system, in larger sizes, can handle heavy duty machining operations." What is the operating range of a Quick-Change collet? The operating range is ± 1/64" (.393mm) when used on multi-spindle automatics for bar stock work. The operating range of the collets when used on CNC lathes is -1/64" (.393) to +.008" (.20 mm). Note that the best grip is with a full bearing, which is at the rated size of the collet. As the stock gets larger, the collet will grip at the edges of the slots; as the stock gets smaller, gripping will be at the center of the gripping surface.