DIN 938 Double End Studs

DIN 938 double end studs are the shortest-engagement option in the DIN double-end stud family, with a tap-end thread length of 1d. This 1d screw-in length is intended for tapped holes in steel or hardened materials that can develop full thread load within one nominal diameter. When the base material is softer—aluminum, cast iron, or similar—the 1d engagement may strip, and a longer standard such as DIN 835 (2d) or DIN 939 (1.25d) should be used instead.

The tap-end thread is produced to tolerance class Sk6, a tight fit that resists loosening once installed. The nut-end thread uses class 6g. A dimensional convention unique to this standard is that the nominal length (l) excludes the tap-end thread (b₁). An M10×75 stud, for example, has a 10 mm tap-end thread and an overall length of 85 mm. DIN 938 covers metric coarse threads from M3 to M52 and fine threads from M8×1 to M52×3, in product grade A. Property classes include 5.6, 8.8, and 10.9 for steel, and A2-70, A4-70, and A4-80 for stainless steel.

These studs are used where a component must be clamped and later removed without disturbing the stud’s fixed end. Valve bodies, pump housings, engine and transmission mounts, gearbox covers, and piping flanges are common installations. In catalogues, they may be listed as double ended studs, double end stud bolts, or tap-end studs. The critical selection check is whether the base material can sustain the 1d engagement; if not, a longer-engagement stud is required.