Withdraw the spindle from the anvil by unscrewing the knurled thimble.
Insert the round stock between the faces of the anvil and the spindle.
Close the spindle against the round stock by turning the ratchet stop then screwing the thimble to moderate tightness.
Tighten the lock nut to fix the spindle and prevent slippage.
Read the digital display to find out the round stock measurement.