Cold finish and Precision ground Tolerances
Cold finish and centerless ground bar have the same diameter tolerances, depending on size and standard commercial straightness tolerance.
Screw Machine Quality (SMQ) bar have tight diameter tolerances usually .0002" ---.0005" with, sometimes ovality tolerances as well. Commercial straightness apply.
Precision Ground bar is always a +/-.0005 diameter tolerance and a standard commercial straightness tolerance.
Turn, Ground and Polish bar (T,G&P) have a plus zero, minus something tolerance depending on size, with standard commercial straightness tolerances.
Bearing Shaft Quality bar (BSQ) have a plus zero minus one-half thousand to minus three thousands tolerance depending on customer needs and a standard commercial straightness tolerance.
Pump Shaft Quality bar (PSQ) usually will have a plus zero minus tolerance on the diameter. This will vary from customer to customer. The big difference between PSQ bar and all others is straightness requirements. PSQ bar will have a precision straightness call out. This will also vary between customers. Normal tolerances range between .0005/ft ---.003/ft.