Metric Round Die (M12x1.75)

The volume of metal being removed at this diameter is considerable, and the force required is correspondingly high. Three things follow. Cutting oil must be applied generously and continuously, not once at the start — dry cutting tears the thread flanks, blunts the die and multiplies the effort. The die must be backed off half a turn for every turn forward to break and clear the chip, because at M12 a die packed with swarf simply stops cutting and starts tearing. And the die stock must be turned with both hands evenly, since uneven force tilts the die and a thread cut at an angle cannot be corrected.

The rod also needs a proper chamfer on the end. At this size a square-cut end is genuinely difficult to start a die on, and forcing the start is how crooked threads begin.

The uses are structural. Making studs from plain M12 rod for chassis, engine and heavy machinery mountings. Replacing a sheared stud with one cut to the original length. Restoring the leading threads on large mounting and suspension bolts. And chasing structural threads before assembly — which is worth doing, because a torque figure assumes a clean thread, and torque consumed by friction in a corroded or damaged thread never becomes clamping force in the bolt. A structural joint tightened to specification through a fouled thread is under-clamped and nobody knows.

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

The buyers are commercial vehicle, truck and plant workshops, structural and heavy fabrication, engineering shops, agricultural and plantation engineering, industrial maintenance, and hardware dealers supplying heavy trades.

Cut the rod slightly over length, since the final thread or two a die produces are always incomplete and are best trimmed off with a hacksaw and dressed with a file. Ask us on WhatsApp for a price, or with the matching M12 tap.