Metallics JQK20 10 x 1/2 in. 1/4 Hex Head Slotted Sharp Point Self-Piercing & Tapping Screws - Steel Zinc - Each

Either works. The JQK20 has a hex head measuring 0.244 to 0.25 inch across, so a 1/4 inch hex driver or nut setter seats on it, and the head is also slotted (slot width 0.045 to 0.054 inch, depth 0.052 to 0.074 inch) for a flat blade when you cannot get a driver square on the work. Most installers run the hex and keep the slot for tight corners or final snugging.

No. It is a sharp point self-piercing and tapping screw, so the point punches its own hole in thin sheet and the thread forms the mating thread as it goes. That is the whole reason to use this type over a standard tapping screw, which needs a drilled or punched hole first. Twin lead threads keep the driving torque down so the point does not walk before it bites.

They do not. Metallics states head dimensions on self-piercing screws differ from standard tapping screws, and there is no single industry standard for self-piercing screw dimensions, so the published figures are a guide and deviations can occur. Worth knowing if your drawing calls out a tapping screw head by dimension. Note also that the JQK20 is neither ARRA nor Buy American compliant, with origin listed as multiple countries, so it will not satisfy domestic-content requirements on a federally funded project.

It is a #10 diameter by 1/2 inch long screw with 12 threads per inch. The 1/2 inch length is short on purpose: it is meant for sheet metal duct, boxes, straps and channel where you only need enough thread to pass through the sheet and engage, not for fastening into thick stock.

The JQK20 is case hardened to Rockwell C28-38 from AISI 1018-1022 steel, which is what lets the sharp point pierce sheet steel without rolling over. Metallics lists it for the electrical, plumbing, heating and air conditioning trades, which is exactly duct seams, box and strap mounting, and channel work.

Yes, the head carries an integral washer with a 0.384 to 0.414 inch outside diameter and 0.019 to 0.031 inch thickness, with head height running 0.096 to 0.11 inch. That washer face spreads the clamp load so the head does not pull through thin sheet, and it covers a slightly oversized pierced hole. There is also an undercut below the head so more thread length engages the material.

The JQK20 is steel with a zinc finish, which is a general purpose coating for dry indoor service, interior duct runs and panel work. For sustained exterior exposure, washdown areas or anywhere corrosive, step up to a stainless or a heavier coated fastener instead of relying on plain zinc.

They ship in a jar of 100, and 100 is the order minimum, so one jar is the smallest buy. The packed jar weighs 0.53 lbs. Other sizes and quantities in the series are available by request.