Metallics JRM99SLT 1/4-20 x 1/2 in. Round Head Slotted Machine Screws - Steel Zinc - Each

Yes. The Metallics JRM99SLT is a 1/4-20 machine screw, 20 threads per inch, so it mates with any 1/4-20 tapped hole, nut, or threaded insert. Machine screws like this are fully threaded straight-shank fasteners, not tapping screws, so the hole has to be pre-tapped or you need a nut on the back side.

The JRM99SLT is 1/2 inch long under the head, and because the round head sits on top of the surface rather than countersinking, all 1/2 inch is available as grip plus thread engagement. Subtract your panel or bracket thickness to see how much thread is left in the tapped hole. For 1/4-20 you want at least one diameter of engagement, so about 1/4 inch of thread in the tapped part, which means a panel thicker than about 1/4 inch leaves you short.

Tensile strength is 60,000 psi minimum, with a hardness of Rockwell B70 to B100, made from AISI 1006 to 1022 low carbon steel. That is standard commercial-grade machine screw strength, fine for mounting devices, covers, brackets, and panel work. For a structural or high-vibration load you want a graded bolt instead.

Zinc plating on steel is a mild corrosion barrier, suited to dry indoor and protected locations. In wet, washdown, coastal, or buried conditions the plating gives up and the steel rusts. For those openings go to a stainless machine screw of the same 1/4-20 x 1/2 size instead.

The JRM99SLT is flagged compliant for both ARRA and Buy American in Metallics' data, with country of origin listed as China. On a federally funded project, verify which standard your contract invokes, since the compliance flag and the origin are both part of the submittal record.

Round head, which is what the JRM99SLT is, sits on the surface and needs no countersink, so it works on flat drilled plate, strut, and sheet metal brackets. Choose a flat head only when the hole is countersunk and the fastener has to finish flush. A round head also spreads load over a 0.443 to 0.472 inch bearing face, which is useful on thin sheet.

They ship in a jar of 100, and 100 count is the order minimum. That jar weighs 0.99 lbs. For MRO cribs and electrical shops it is a shelf-stable count for a common size; larger quantities and other sizes are available on request from Metallics.

Slotted drive, which is what these carry, is the hardest drive to keep a bit seated in under power. The slot is only 0.064 to 0.075 wide and 0.082 to 0.109 deep, so a powered driver tends to cam out and mar the head. Hand drive them, or run a clutch setting low with firm down pressure. If you are installing by the hundred and want a power-friendly head, specify a Phillips or combo drive version from the Metallics line instead.