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Description
FINISHED THREADM12 × 1.75
VARIANT2×D (24 mm)
MATERIALStainless steel
SYSTEMV-Coil
M12 2xD thread repair insert – V-Coil DIN 8140 helical thread insert
Thread insert technical data table
| V-COIL M12 2×D THREAD REPAIR INSERT | |
|---|---|
| Restored thread | M12 × 1.75 |
| Thread pitch P | 1.75 mm |
| Length variant | 2×D |
| Insert height | 24 mm |
| Repair system | V-Coil |
| Compatible tap | M12 4H V-Coil |
| Pre-drilled hole | Ø12.4 mm |
The V-Coil M12x1.75 thread repair insert is a resilient Helicoil-type stainless steel wire coil. When screwed into a hole tapped with an STI thread repair tap, it creates a fully functional M12 thread for a standard screw. The repair does not require a larger screw or replacement of the entire part. The 2xD version with a height of 24 mm is selected for standard joint loads. Insert dimensions are specified by DIN 8140, form A (free-running).
M12 thread repair step by step – from the hole to the completed joint
Four installation steps in the V-Coil system
Thread repair process M12 × 1.75
1Prepare the hole
diameter: Ø12.4 mm
2Tap the thread
tool: V-Coil 4H
3Screw in the insert
length: 2×D
✓Restore the joint
thread: M12 × 1.75
Screw in the insert using an installation tool — do not stretch it or twist it sideways.
Practical installation checks
After tapping, remove chips and coolant from the hole. Guide the insert with an installation tool without applying pressure — it should screw in easily. The correct depth is 1/4–1/2 of a turn below the material surface. Break off the tang with a punch, and remove the broken piece from a blind hole.
Helicoil-type insert made from diamond-section wire – construction and operating principle
How the insert stays in the hole
The insert wire has a diamond-shaped cross section, so it works on both sides simultaneously: the outer edge engages the thread in the hole, while the inner edge forms a new thread for the screw. Before installation, the coil is slightly larger than the hole. As it is screwed in, the coils compress; when the tool is released, they expand and lock permanently in place — without adhesive. The wire has a minimum tensile strength of 1400 MPa — the new thread is harder and smoother than a thread cut directly into the material.
Why a standard M12 tap will not work here
The insert wire has a thickness of approx. 1.14 mm (calculated from the thread pitch: 0.65 × 1.75 mm).
The thread for the insert must accommodate the wire on both sides of the profile, so its diameter is approx. 14.28 mm — approximately 2.3 mm larger than a standard M12 thread (12 mm).
This enlarged thread can only be cut with a thread repair tap M12 4H V-Coil, after drilling the hole Ø12.4 mm. Once the insert is screwed in, the screw again engages a standard thread M12 × 1.75.
M12 thread repair in steel, stainless steel, cast iron and aluminum
When to choose the 2xD version
The insert restores threads in steel, stainless steel, cast iron, and aluminum, as well as magnesium and plastics. The 2xD version is suitable for typical joints under moderate loads. A shorter insert is selected for a shallow hole and hard steel. A longer one is used in soft material and with screws of property class 8.8 and higher. In practice, M12 is used in machine mountings and steel structures, among other applications. The first thread carries approximately half the force, as shown in the load distribution table below.
Thread strength: how much load each turn carries
| Thread turn | Standard thread (without an insert) | Thread with a V-Coil insert |
|---|---|---|
| 1 (first from the screw head) | 50% | 30% |
| 2 | 25% | 22% |
| 3 | 12% | 17% |
| 4 | 6% | 13% |
| 5 | 3% | 10% |
| 6 | 2% | 8% |
How to read the table: when the screw is tightened, each thread turn carries part of its load. In a standard thread, the first turn carries as much as 50% of the load — and it strips first. With an insert, the same turn carries only 30% because the load is distributed over the entire thread length. Catalog data from wire thread insert manufacturers.
M12 2×D insert compatibility – required V-Coil system tools
Check before purchasing
✓Nominal thread: M12 with a pitch of 1.75 mm.
✓Tap: special M12 4H V-Coil thread repair tap.
✓Tap drill hole: Ø12.4 mm drill bit.
▲Depth: space for an insert 24 mm high and proper seating.
▲
Application limitations
The thread for the insert must be cut with an M12 4H V-Coil STI tap — a nominal M12 thread is too small for the insert to anchor in it. The free-running version does not prevent the bolt from loosening: threadlocker or a screw-locking insert helps under vibration.
After the V-Coil M12 2xD thread repair insert is installed, the screw determines the load limit of the joint, rather than the thread in the part. The hole must accommodate the 24 mm insert (2 × 12 mm), including the correct recess below the surface. In addition to repairs, the insert is suitable for reinforcing threads during manufacture.
Frequently asked questions
The length is determined by the parent material and the screw property class: the weaker the material and the stronger the screw, the longer the insert. The 1.5xD version is suitable for steel, cast iron, and shallow holes, 2xD is standard for aluminum, and 2.5–3xD is selected for soft materials and screws of property class 8.8 and higher. This insert has a length of 2xD (24 mm).
The top turn of the insert should sit 1/4–1/2 of a turn below the material surface. After installation, the tang is broken off with a punch. In a blind hole, the broken fragment must be removed before installing the screw.
Yes, because insert dimensions are specified by the standard DIN 8140 and ASME B18.29.1. This makes Helicoil, V-Coil, Recoil, and BaerCoil products interchangeable. Size, pitch, and length must match.
Yes, the same inserts are factory-installed to reinforce threads in cast iron and aluminum. The thread gains the hardness of wire with a minimum tensile strength of 1400 MPa and uniform load distribution. This improves the fatigue life of the joint.
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| Courier GLS | Przelew24 / Prepayment | 14,76 zł gross | Delivery time 1 working day |
| Courier GLS | Cash on delivery | 17,26 zł gross | Lead time 1 working day |
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