Metallics JRM105SLT 1/4-20 x 2-1/2 in. Round Head Slotted Machine Screws - Steel Zinc - Each

The Metallics JRM105SLT is a 1/4-20 thread, 20 threads per inch, which is a coarse UNC machine thread. It mates with any 1/4-20 tapped hole or 1/4-20 nut. It is not the 8-32 or 10-32 thread used for device yokes and cover plates in standard outlet boxes, so for those openings you need a smaller machine screw. Use the 1/4-20 where the tapped hole or threaded insert is 1/4-20, such as strut fittings, channel nuts, and equipment frames.

Tensile strength is 60,000 psi minimum with a hardness of Rockwell B70-B100, made from low carbon steel in the AISI 1006 to 1022 range. That is standard low carbon machine screw material, suitable for general mounting, bracketry, and equipment fastening. It is not a graded structural bolt, so if a drawing calls out a grade such as SAE Grade 5 or Grade 8 or an ASTM structural bolt, this screw is not the substitute.

No. The JRM105SLT is the screw only, 100 to a jar. A machine screw has a blunt end and a full machine thread, so it needs either a tapped hole in the part or a matching 1/4-20 nut, and usually a flat washer, ordered separately. It will not cut its own thread in sheet metal the way a self-tapping screw does.

At 2-1/2 inches of overall screw length under the round head, the JRM105SLT gives you grip for assemblies up to roughly 2 inches thick once you allow for a nut and a washer. Machine screw length is measured from under the head on a round head, so the full 2-1/2 inches is usable through the joint. For thinner stock the same 1/4-20 is sold in shorter lengths in the Metallics JRM series.

Head width runs 0.443 to 0.472 in. and head height 0.16 to 0.175 in. That domed round head sits proud of the surface rather than flush, so it needs clearance above the material. If the application calls for a flush face you want a flat head screw with a countersunk hole instead.

Zinc plated low carbon steel is a mild corrosion finish meant for dry interior service. In wet, washdown, coastal, or exterior conditions the plating sacrifices itself and the steel underneath will rust, so a stainless machine screw is the better call there. Keep the zinc plated JRM105SLT to indoor panels, boxes, and equipment mounting.

The JRM105SLT is flagged compliant for both ARRA and Buy American, with country of origin China. On a federally funded job, confirm which standard your specification invokes, since those two flags and the origin need to be read together by whoever is certifying the submittal.

They ship in a jar, with a minimum order of 100 count. That makes it a shop or truck stock item rather than a single-piece buy, which is how most MRO and electrical crews want a common 1/4-20 length stocked.

A jar of 100 weighs 3.01 lbs, and the container measures 3.5 in. by 3.5 in. by 5.75 in. Useful if you are working out box count or truck stock space across several sizes.