Metallics JMHTB1055 Bolts M10 x 55 C8.8 Hx Tap Blt St-zn (Jar 50)

The JMHTB1055 is an M10 bolt with a 1.5 mm thread pitch, right hand, so it threads into a standard M10 x 1.5 coarse tapped hole or nut. Shank length under the head is 55 mm. Because it is a tap bolt, the thread runs all the way up to the head, which is what you want when you are pulling into a blind tapped hole and need thread engagement right at the surface.

Grade 8.8 is the medium carbon, heat treated class, rated at 120,350 psi minimum tensile and 95,700 psi minimum yield, with a hardness of Rockwell C23-34. That is the usual class specified for motor mounting and equipment anchoring into tapped holes, and mounting a motor to machinery is exactly what Metallics lists this bolt for. For a loaded mount, torque to the Class 8.8 value for M10 rather than to a grade 5 figure, since the two are not the same.

No. The JMHTB1055 is not Buy American compliant and not ARRA compliant, with country of origin listed as multiple. If your specification carries a domestic sourcing requirement, you need a bolt with a stated domestic origin instead.

The bolt is medium carbon steel with a zinc finish. Zinc plating handles indoor mechanical rooms, equipment skids, and sheltered work well. For sustained wet exposure, rooftop curbs, or coastal air, zinc plated carbon steel will eventually corrode, so hot dip galvanized or stainless is the better call there. Metallics lists this one for electrical, plumbing, heating, and air conditioning work.

It is a hex head bolt. An M10 Class 8.8 hex bolt to metric standard takes a 17 mm wrench or socket across the flats, which matches the head width Metallics publishes for it. There is a washer face under the head, so it seats flat without a separate flat washer, though a washer is still worth using on soft or painted surfaces.

Fifty bolts per jar, and 50 each is the order minimum. The jar pack is the reason for the JMHTB prefix in the series (MHTB and JMHTB) rather than bulk boxing, which is handy for a service van or a shop bin. The full jar weighs 1,982 g.

A tap bolt is threaded the full length of the shank right up under the head, while a standard hex cap screw has a plain unthreaded grip section below the head. Full thread, as on this M10 x 55 Class 8.8, lets you use whatever engagement depth the tapped hole gives you and makes one length work across several different clamp thicknesses. The plain grip version is preferred where a shear load bears on the unthreaded body rather than on threads.