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Description
FINISHED THREADM16 × 2
TOLERANCE4H
PRE-DRILLED HOLEØ16.5 mm
LENGTH L1112 mm
M16 thread repair tap – STI tap for V-Coil M16x2 inserts
Tool dimension table and technical data
| V-COIL M16 THREAD REPAIR TAP | |
|---|---|
| Thread to be repaired | M16 × 2 |
| Tolerance class | 4H |
| Tap diameter B | 18.6 mm |
| Overall length L1 | 112 mm |
| Flute length L2 | 37 mm |
| Shank diameter D2 | 14 mm |
| Square drive a | 11.2 mm |
| Pre-drilled hole | Ø16.5 mm |
The M16 V-Coil thread repair tap cuts an STI (Screw Thread Insert) thread in a damaged hole for a Helicoil-type insert. The tool restores a load-bearing hole without increasing the screw size, so the design retains its original dimensions. Once the insert is installed, the hole accepts a standard M16 screw again without modification. The 14 mm shank with a 11.2 mm square drive fits standard hand tap wrenches.
Repairing a stripped M16 thread 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 hard and soft parent materials. Threads strip most frequently in soft metals, while in steel the insert increases the fatigue life of the joint. Applications include securing heavy equipment and machine bodies where joints are frequently disassembled. Drill the pilot hole with a drill bit Ø16.5 mm for the STI tap, drill at the upper tolerance limit, and tap with coolant.
The cut STI thread has dimensions conforming to DIN 8140-2, so the M16 thread repair tap prepares a hole for any insert conforming to this standard — lengths of 2xD are available in the store. The tool measures 112 mm (L1) with a flute length of 37 mm (L2), and the repaired thread carries loads comparable to or greater than those of the original.
M16 thread repair step by step
From drilling to the nominal thread
Repairing with an insert is faster and less expensive than replacing a machine body, for example when maintaining construction machinery.
Thread repair M16 with a wire insert
1Drilling
Hole: Ø16.5 mm
2Chamfering the hole entrance
Angle: 90–120°
3STI tapping
With coolant, 4H
4Insert installation
Tang: break off
✓Nominal thread
Screw: M16 × 2
In a blind hole, remove the broken-off tang before installing the screw
Helicoil M16 tap (STI) – why it is larger than a standard tap
Compensating for the wire thickness of the thread insert
The STI thread retains the pitch P = 2 mm and the 60° thread angle of the ISO metric thread, but its diameter is intentionally enlarged. The increase compensates for the insert wire thickness on both sides of the profile, according to the following relationship: D STI = 16 + 1.3 × P = 16 + 1.3 × 2 = 18.6 mm. Therefore, the tool's cutting diameter B is 18.6 mm — a nonstandard value that neither an M18 nor an M20 tap can provide. The 4H tolerance corresponds to inch thread class 3B and is also suitable for screw-locking inserts; once the insert is installed, the finished thread achieves the standard 6H class.
Tap compatibility with the V-Coil insert
What must match before starting the repair
✓Matching size: V-Coil M16 insert with a 2 mm pitch.
✓Matching hole: prepare a Ø16.5 mm diameter before tapping.
✓Matching version: available M16 insert lengths: 2xD.
▲Required inspection: depth and wall thickness of the component being repaired.
Tool exclusively for insert threads
The thread cut by this tool is larger than nominal and is intended exclusively for installing a V-Coil insert. Use a standard tap to cut a regular M16 thread — never use it to cut the seat for an insert.
Frequently asked questions
For the STI insert, use a drill bit Ø16.5 mm, while a standard M16 thread requires only 14 mm. Drill at the upper tolerance limit and chamfer the hole entrance at an angle of 90–120°. This facilitates tool entry and protects the first thread turns from chipping.
The STI tap cuts a larger profile with a major diameter of approximately 18.6 mm instead of 16 mm, because it accommodates twice the 1.3 mm wire thickness. The 2 mm pitch and 60° angle remain identical to those of a standard tap. DIN 8140 ensures that Helicoil, V-Coil, Recoil, and BaerCoil inserts are interchangeable.
Yes, the inner edge of the wire recreates the nominal thread M16 × 2, so a standard screw can be installed without modification. The minor diameter after installation is approximately 13.84 mm and complies with ISO 724.
Yes, the free-running version can be used with threadlocker or a self-locking nut. For severe vibration, screw-locking inserts are available in accordance with DIN 8140 form B, with a polygonal coil that locks the screw.
Product accessories
HSSE 16.5 cobalt metal drill bit DIN 338
Reference: 13295 In stock < 10 items
€17.63
€21.69 brutto
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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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