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Helicoil tapping M2.5x0.45 - Artykuły Techniczne
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  • Helicoil tapping M2.5x0.45 - Artykuły Techniczne
Varel

Thread repair tap M2.5x0.45 4H V-Coil

Varel Varel
0000011369
€5.83 tax inc.

Net price: €4.74

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Description

FINISHED THREADM2.5 × 0.45
TOLERANCE4H
PRE-DRILLED HOLEØ2.6 mm
LENGTH L148 mm

M2.5x0.45 thread repair tap – STI tap for V-Coil M2.5x0.45 inserts

Tool dimension table and technical data

V-COIL M2.5x0.45 THREAD REPAIR TAP
Thread to be repairedM2.5 × 0.45
Tolerance class4H
Tap diameter B3.1 mm
Overall length L148 mm
Flute length L211 mm
Shank diameter D23.15 mm
Square drive a2.5 mm
Pre-drilled holeØ2.6 mm
V-Coil M2.5x0.45 4H thread repair tap for cutting STI threads for Helicoil-type M2.5x0.45 wire thread inserts

The V-Coil M2.5x0.45 thread repair tap cuts an STI (Screw Thread Insert) thread for a Helicoil-type insert. The tool restores a load-bearing seat in a damaged hole without increasing the screw size. Once the insert is screwed in, the hole accepts a standard M2.5x0.45 screw again, and the joint regains its original strength. The 3.15 mm diameter shank with a 2.5 mm square drive fits standard hand tap wrenches.

Repairing stripped M2.5x0.45 threads in steel, stainless steel, cast iron, and aluminum

Materials, tips, and limitations

The tool works in steel, stainless steel, cast iron, and aluminum, covering both industrial structures and light alloys. Threads strip most frequently in soft metals, while in steel the insert increases the fatigue life of the joint. M2.5x0.45 thread repair is useful in electronics, cameras, and drones, among other applications where retaining the original screw size is essential. Predrill the hole with a drill bit Ø2.6 mm for the STI tap, drill at the upper tolerance limit, and tap with coolant.

The M2.5x0.45 thread repair tap cuts an STI thread with dimensions conforming to DIN 8140-2. The tool's overall length L1 is 48 mm, and its flute length L2 is 11 mm. The tool is compatible with V-Coil inserts in lengths of 2.5xD, and a properly repaired thread carries loads comparable to or greater than the original thread.

Repairing an M2.5x0.45 thread step by step

From drilling to the nominal thread

Repairing with an insert is faster and less expensive than replacing the entire body, such as a camera housing or drone frame.

Thread repair M2.5x0.45 with a wire insert

1Drilling

Hole: Ø2.6 mm

2Chamfering the hole entrance

Angle: 90–120°

3STI tapping

With coolant, 4H

4Insert installation

Tang: break off

✓Nominal thread

Screw: M2.5 × 0.45

In a blind hole, remove the broken-off tang before installing the screw

M2.5x0.45 Helicoil tap (STI) – why it is larger than a standard tap

Compensating for the wire thickness of the thread insert

The STI tool differs from a standard M2.5x0.45 tap only in profile size — the 60° angle and 0.45 mm pitch remain metric. The insert wire takes up space on both sides of the profile, so the diameter is D STI = 2.5 + 1.3 × 0.45 = 3.08 mm; hence the nonstandard 3.1 mm cutting section, which neither an M3 nor an M4 tap can provide. Tolerance class 4H (equivalent to inch class 3B) is also used for screw-locking inserts, while the finished thread after insert installation is class 6H.

Tap compatibility with the V-Coil insert

What must match before starting the repair

✓Matching size: V-Coil M2.5x0.45 insert with a 0.45 mm pitch.
✓Matching hole: prepare a Ø2.6 mm diameter before tapping.
✓Matching version: available M2.5x0.45 insert lengths: 2.5xD.
▲Required inspection: depth and wall thickness of the component being repaired.

This is not a standard M2.5x0.45 tap

The tool prepares an oversized mounting thread for a V-Coil insert. Do not use it to cut a standard M2.5x0.45 thread without an insert, and do not substitute a standard tap for it when installing an insert.

Frequently asked questions

For the STI thread, drill a hole Ø2.6 mm, which is larger than the 2 mm required for a standard M2.5x0.45 thread. Stay at the upper diameter tolerance limit so the insert fits freely. Chamfer the hole entrance at 90–120° to help engage the first thread.

The STI tap cuts a thread with a major diameter of approximately 3.08 mm instead of 2.5 mm, because it accommodates two wire thicknesses of 0.29 mm each. The 0.45 mm pitch and 60° thread profile remain the same as those of a standard tap. DIN 8140 ensures that Helicoil, V-Coil, Recoil, and BaerCoil inserts are interchangeable.

The 4H designation indicates a close STI thread fit class, equivalent to inch class 3B used in aerospace and screw-locking inserts. After the insert is installed, the working thread achieves class 6H, the standard for metric screws. The closer fit ensures that the insert seats securely in the miniature hole.

Use a torque screwdriver and set the torque to approximately 0.3–0.6 Nm for an M2.5 screw and approximately 0.6–1.0 Nm for M3. A thread restored with a stainless steel insert with a minimum tensile strength of 1400 MPa is harder than a thread cut in aluminum. This allows it to withstand more assembly and disassembly cycles without damage.

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Thread repair tap M2.5x0.45 4H V-Coil

Thread repair tap M2.5x0.45 4H V-Coil

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