Metallics DS172M 12 x 1-1/4 in. 5/16 Indented Hex Head Slotted Sharp Point Tapping Screws - Steel Zinc - Each

The DS172M #12 x 1-1/4 in. tapping screw ships as a box of 1,000, which is also the order minimum. Pack type is Box, and the shipping box runs 11.7 lbs. If you need a smaller count or a different length, Metallics notes other sizes and quantities are available by request.

A Type A screw is for thin sheet metal and it needs a pilot hole sized to the material, not no hole at all. The DS172M uses a gimlet (sharp) point with 11 threads per inch, a coarse spacing that cuts its own thread as it drives. In thin gauge steel or in wood it will start readily; in heavier gauge you drill first. It is not a self-drilling screw.

Metallics lists the DS172M as both ARRA compliant and Buy American compliant. Country of origin is recorded as multiple. For federally funded work, procurement will want the compliance flag documented on the submittal, and that flag is carried on the part.

Two options, which is the point of the head. The DS172M has a 5/16 in. indented hex washer head (head width 0.305 to 0.312 in., 0.34 in. across corners), so a 5/16 nut driver or socket seats it. It is also slotted, slot width 0.056 to 0.067 in. and depth 0.077 to 0.093 in., so a medium flat blade works in tight spots where a driver will not fit.

Head dimensions follow ASME B18.6.3-2010 and the thread form follows ASME B18.6.4. Material is AISI 1016 to 1024 carbon steel with a zinc finish, case hardness Rockwell C28-38, and minimum torsional strength of 83 lb-in. One caveat Metallics states: dimensions for #9 diameter screws fall outside ASME B18.6.4.

Minimum torsional strength on the DS172M is 83 lb-in, and the case is hardened to Rockwell C28-38. That is the limit the screw body will take before twisting off, and most cordless impacts exceed it easily, so run them on a clutch or a low setting and finish by feel. The 5/16 hex head itself will not cam out the way a slot can.

Yes, it is a hex washer head. The integral washer measures 0.398 to 0.432 in. outside diameter with a washer thickness of 0.022 to 0.039 in., and overall head height runs 0.139 to 0.155 in. That flange spreads the load over sheet metal or a strap so the head does not pull through, and it means no separate washer in the kit.

The DS172M is carbon steel with a zinc finish, which is a dry-interior plating. It suits boxes, enclosures, straps and strut work indoors. For exterior, wet, or corrosive locations, specify a stainless or hot dip galvanized tapping screw instead rather than relying on zinc plate.

Order Metallics DS172M, a #12 diameter by 1-1/4 in. long Type A tapping screw from the JDS series, indented hex slotted head with a 5/16 in. hex, steel zinc. Quantity is per thousand.