Metallics JMHTB1270 Bolts M12 X 70 C8.8 Hx Tap Blt St-zn (Jar 50)

Fully threaded. The JMHTB1270 is a metric hex tap bolt, meaning the thread runs all the way up the shank to directly beneath the head, with a washer face under the head. That matters when you are clamping a thick assembly and need thread engagement anywhere along the 70mm length, rather than a partially threaded cap screw that only grips near the tip.

It is an M12 x 1.75 right hand thread, which is the coarse metric pitch, so it mates with any standard coarse M12 nut or tapped M12 hole. If your tapped hole is fine pitch M12 x 1.25 or x 1.5, this bolt will not start in it.

Class 8.8 is the medium carbon steel, heat treated grade that covers most structural and machinery bolting in metric. On the JMHTB1270 that works out to 120,350 psi minimum tensile and 95,700 psi minimum yield, with a hardness of Rockwell C23-34. The bolt is sold for mounting motors to machinery and is common in automotive and truck repair. For higher clamp loads you would step up to Class 10.9 or 12.9.

It is metric. JMHTB1270 decodes as M12 diameter by 70mm long, Class 8.8, hex head tap bolt, steel with zinc. It is not a 1/2 inch bolt, and while 1/2-13 is dimensionally close, the threads are not interchangeable with M12 x 1.75.

They ship 50 to a jar, and 50 is the order minimum, so a jar is the smallest buy. Metallics does offer other sizes and quantities in the MHTB and JMHTB tap bolt series on request if M12 x 70 is not the length you need.

The JMHTB1270 is steel with a zinc plated finish. Zinc plating is a light corrosion coating meant for dry or protected indoor service, machinery rooms, equipment skids and vehicle work. For sustained exposure to weather, washdown or coastal air, go to hot dip galvanized or stainless.

The bolt has a washer face formed under the hex head, which gives a clean bearing surface against the joint. That is not the same as a flat washer, though. On soft materials, oversized or slotted holes, or where you want to spread the clamp load, you should still add a hardened flat washer. Nuts and washers are not included with the jar of 50.