Pen Mandrel Shaft B.

A mandrel is a round steel rod that you slide the wood blank with the brass tube inserted onto. Unlike most other companies who offer only one size mandrel we sell two sizes. The A mandrel (sometimes called a "7mm" mandrel) which is 0.247 +0 -0.002 inches in diameter and and other mandrel which has a larger diameter, the B mandrel. This is 0.291 +0 -0.002 inches in diameter. We use the B mandrel on some kits because the thicker diameter helps prevent whip while turning and allows for a much better result.