Dowel Pin

Zylinderstift is the German word for a dowel pin (parallel pin). It appears on German drawings and bills of material, usually followed by a DIN or ISO number, a diameter with tolerance, a length and a material — for example DIN 7 - 6 m6 x 20 - A2.

DIN 7 was replaced by ISO 2338: unhardened parallel pins in steel or stainless steel. DIN 6325 was replaced by ISO 8734: hardened and ground dowel pins with an m6 diameter tolerance. The old DIN numbers are still widely used on drawings.

Diameter × length in millimetres, with the diameter tolerance in brackets: 6(m6)*20 is a 6 mm pin, m6 tolerance, 20 mm long. Sizes written without a tolerance are our standard slip-fit pins.

An m6 pin is slightly over nominal (a 6 mm m6 pin is +0.004 to +0.012 mm) and presses into an H7 hole to stay put. An h7 pin is at or slightly under nominal (0 to -0.012 mm) and slips into an H7 hole so it can be removed.