Metric Round Die (M8x1.25)

That gives thread quality a real consequence. An M8 bolt in a load-bearing joint is tightened to a torque figure, and torque is only a proxy for the tension in the bolt. If the thread is torn, corroded or full of paint, a large part of the applied torque is consumed by friction and never becomes clamping force — so a joint tightened correctly through a bad thread is under-clamped and will work loose in service, while everyone believes it was done to specification. Running a die down a bolt before it goes into a structural joint is a short job that makes the torque figure mean something.

Making studs is the other main use. Threading plain M8 rod produces studs of any length, which is how a workshop fabricates a mounting rather than waiting for a part, and how a broken stud is replaced with one cut to the original length.

The 1.25 is the coarse pitch for M8. A fine 1.0 pitch also exists on vehicle and machinery work, and the two are not interchangeable — a fine nut will start on a coarse thread and then jam, so identify the pitch before you cut.

The material is 9CrSi alloy steel, a chromium-silicon tool steel taking a high hardness at the cutting edges while keeping the toughness not to chip.

The buyers are vehicle, commercial vehicle and plant mechanics, engineering and fabrication shops, maintenance fitters, agricultural and machinery workshops, and hardware dealers.

Three habits. Chamfer the rod end before starting, since a square end resists the die and forcing the start cuts a crooked thread. Check squareness after two turns from two directions. And use cutting oil generously, backing off half a turn per turn forward — at M8 there is enough metal being removed that a die packed with swarf will stop cutting and start tearing the thread face. Ask on WhatsApp for a price, or with the matching M8 tap.