Collet & Chuck Capacity Calculator

Because a collet collapses as a single continuous slotted sleeve that closes evenly around the entire circumference of the part, distributing the clamping force symmetrically. A three-jaw chuck grips at only three discrete contact points, and any small difference between the jaws' actual positions (from wear, backlash, or manufacturing tolerance) shows up directly as runout at the part. That's why collets typically hold around 0.0005 in TIR versus a chuck's 0.002-0.005 in -- several times looser -- even though a chuck can grip a far wider range of diameters.

Because a collet or jaw set is designed to develop its full rated clamping force when properly seated at its nominal diameter -- that's the geometry the manufacturer engineered the clamping mechanism around. As the actual part diameter deviates from nominal, the collet or jaws are collapsed either less or more than their optimal position, and less of the actuating force converts into effective clamping pressure on the part. This calculator models that falloff as scaling with how far the deviation is toward the edge of the collapse range or jaw stroke.

Not necessarily. Falling inside the diameter range only confirms the workholding can physically close on the part; Effective Grip Force still tells you how much of the device's rated clamping force is actually available at that specific diameter, which directly affects how much cutting force (and therefore how aggressive a cut) the setup can safely resist before the part slips. A part near the edge of the range can fit geometrically while still being held with meaningfully reduced force.

It depends on the tradeoff between precision and range you need. Collets suit production runs of a known, consistent diameter where concentricity matters most, since their narrow collapse range is matched to one nominal size. Jaw chucks suit one-off or varied-diameter work, or larger stock, since their wide jaw stroke accommodates far more diameters without changing tooling -- at the cost of looser concentricity than a properly sized collet would deliver.