Spindle Turning Calculator — Blank Dimensions

Add at least 25mm to each end (50mm total) for the drive centre and live centre to grip. If you are turning a piece that needs a tenon or specific detail at the very end, add more accordingly. The extra length is cut off after turning.

The blank should be square with each side at least 10% larger than the finished diameter. This accounts for the corners of the square being rounded off first. For a 40mm finished spindle, start with a 45mm square blank.

Start at lower speeds while the blank is still square (corners spinning). For initial roughing, stay below the calculated max RPM. Once the blank is round, you can increase speed for finer cuts. Thin spindles can run at high speeds; heavy or long ones should run slower.

For spindles longer than about 10x the diameter, use a steady rest to prevent whip (vibration). Alternatively, rough the spindle to near finished size at the steady rest end first, then move the steady and finish the other end. Keep cuts light on long spindles.