16C and 3J Collet Chucks are very similar. The 3J Collet Chuck has a through hole capacity up to 1.750”, versus the 1.625” for a 16C Collet Chuck. The real difference lies in the oversize collets; what Hardinge calls “Step Chucks.”
Hardinge manufactures 16C step chucks that can be purchased from 2” – 6” in diameter by 1” increments. They offer them in two different lengths, ½” and 1-1/4”. The catch is that you have to use a closing ring in order for these to work on your machine. These closing rings are designed to be bolted up onto a spindle that has an (A5) mount. This means that you will need to purchase a 16C collet chuck that has the (A5) configuration on the front face, as shown to the right.
You then will have the capability of using all the step chucks that are available by Hardinge. If you wish to use a 3J Collet Chuck, Hardinge does offer 3J Step Chucks that do not require the closing rings. The 3J Step chucks are available in 2”- 5” with ½” of max bore depth. For more information give us at call: 800-423-5145