Metric Tap (M12x1.75)

Cutting an M12 thread by hand is real work, and it is worth being realistic about it. There is a great deal of metal to remove, the forces are high, and the tap is being twisted hard. That makes three things matter more than at any smaller size.

First, the tapping drill size has to be right. Too small a hole means the tap has more metal to remove than it can handle, and an M12 tap breaking under that load is a serious problem — the tap is harder than the component and cannot be drilled out, so a broken tap usually means a scrapped part. Too large and the thread has insufficient depth and strips under load, which on a structural fastener matters.

Second, chip clearance is critical. Back the tap off half a turn for every turn forward, without exception. A tap that jams on its own swarf is a tap about to break, and at M12 the torque available to you through a bar wrench is more than enough to snap it.

Third, cutting oil, generously and continuously. Dry cutting tears the thread face, blunts the tap and multiplies the force required.

Threads at this size are almost always structural, and that gives chasing a real purpose beyond tidiness. A torque figure assumes a clean thread — torque consumed by friction in a corroded or painted thread never becomes clamping force in the bolt, so a joint tightened to specification through a fouled thread is under-clamped without anyone knowing. Running a tap through first makes the torque wrench mean what it reads.

The material is 9CrSi alloy steel: a chromium-silicon tool steel taking a high hardness at the cutting edges while keeping the toughness to resist snapping.

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. Ask us on WhatsApp for a price.