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Description
FINISHED THREADM3 × 0.5
VARIANT2×D (6 mm)
MATERIALStainless steel
SYSTEMV-Coil
M3x0.5 2xD thread repair insert – V-Coil DIN 8140 helical thread insert
Thread insert technical data table
| V-COIL M3x0.5 2×D THREAD REPAIR INSERT | |
|---|---|
| Restored thread | M3 × 0.5 |
| Thread pitch P | 0.5 mm |
| Length variant | 2×D |
| Insert height | 6 mm |
| Repair system | V-Coil |
| Compatible tap | M3 4H V-Coil |
| Pre-drilled hole | Ø3.1 mm |
The M3x0.5 V-Coil thread repair insert is a resilient coil made from Helicoil-type stainless steel wire. When installed in a hole tapped with a thread repair tap, it creates a fully functional M3x0.5 thread for a standard screw. The hole is repaired without a larger screw or replacement of the entire component. Select the 2xD version with a height of 6 mm for standard joints in aluminum. Dimensions are specified by DIN 8140, form A (free-running).
M3x0.5 thread repair step by step – from the hole to the completed joint
Four installation steps in the V-Coil system
Thread repair process M3 × 0.5
1Prepare the hole
diameter: Ø3.1 mm
2Tap the thread
tool: V-Coil 4H
3Screw in the insert
length: 2×D
✓Restore the joint
thread: M3 × 0.5
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 M3x0.5 tap cannot prepare the hole
A pitch of 0.5 mm means a wire thickness of approx. 0.33 mm (the 0.65 × P rule).
The installation thread for the insert is therefore approx. 3.65 mm in diameter — approximately 0.6 mm larger than the nominal 3 mm of the M3x0.5 thread.
It can only be prepared with a tap M3 4H V-Coil after drilling Ø3.1 mm; after repair, the screw engages a standard thread M3 × 0.5.
M3x0.5 thread repair in steel, stainless steel, cast iron and aluminum
When to choose the 2xD version
The coil restores M3x0.5 threads in steel, stainless steel, cast iron, and aluminum, as well as magnesium and plastics. Select the length according to the parent material and screw property class. The 2xD (6 mm) version is standard for aluminum. Choose the shorter 1.5xD insert for a shallow hole in steel. Use the longer 2.5–3xD insert in soft materials and with screws of property class 8.8 or higher. The repaired thread is suitable for applications such as electronics and precision instruments. The force distribution is shown in the table — the first thread turn carries approximately half the load.
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.
M3x0.5 2×D insert compatibility – required V-Coil system tools
Check before purchasing
✓Nominal thread: M3x0.5 with a pitch of 0.5 mm.
✓Tap: special M3 4H V-Coil thread repair tap.
✓Tap drill hole: Ø3.1 mm drill bit.
▲Depth: space for an insert 6 mm high and proper seating.
▲
What to remember before repair
The insert requires an STI thread cut with a V-Coil system thread repair tap — a standard M3x0.5 tap cuts a smaller thread in which the insert will not seat. The free-running version does not lock the screw: use threadlocker or a screw-locking insert for joints exposed to vibration.
A correctly installed V-Coil M3x0.5 2xD thread repair insert carries loads so that the screw shank fails before the thread in the material. Plan the hole depth: the insert occupies 6 mm, or twice the thread diameter (2 × 3 mm). In series production, the same insert serves as preventive reinforcement.
Frequently asked questions
The length depends on the parent material and screw property class — the weaker the material and the stronger the screw, the longer the insert. For aluminum, 2xD is standard; for steel, cast iron, and shallow holes, 1.5xD is sufficient; and soft materials and screws of property class 8.8+ require 2.5–3xD. This insert has a length of 2×D (6 mm).
No. The coil is larger than the thread in the hole and locks itself permanently in place. Use threadlocker only under severe vibration, or choose a DIN 8140 form B screw-locking insert.
Yes. Insert dimensions are specified by DIN 8140 and ASME B18.29.1, making Helicoil, V-Coil, Recoil, and BaerCoil interchangeable. Matching size, pitch, and length are what matter.
Tighten with a torque screwdriver — for M3, the recommended torque is approximately 0.6–1.0 Nm, and for M2.5, approximately 0.3–0.6 Nm. A thread restored with a wire insert with a minimum Rm of 1400 MPa is harder than one cut in aluminum. This allows it to withstand more assembly and disassembly cycles.
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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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