I recently bought a Super Chuck model 14N for a floor drill press. This
chuck has a capacity of 0" to 1/2 ". I have been checking the TIR using
jobber length drill bits in the 1/8" to 1/4" diameter range. I noticed
the TIR seems to depend on how hard I tighten a drill bit in the chuck.
For example, if I tighten it just using my hands without the key, the
TIR is under 0.001, but if I fully tighten it using the chuck key the
TIR climbs up to 0.004 or so. If use a #1 drill+countersink bit instead
of a jobber drill bit, the TIR change is even more dramatic with a
shift from under 0.001" to about 0.008". These measurements are all at
the top end of the bit, just under the chuck jaws. Is this normal
behavior for these chucks, or perhaps I got a lemon?