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Description
THREAD BEING REPAIREDM5x0.8
THREAD FOR INSERT6.0 mm
INSERT HEIGHT7.5 mm
NUMBER OF REPAIRS15
M5 thread repair kit – 1.5xD helicoil-type inserts
Kit with drill bit, STI tap, installation tool and 15 inserts
| KIT DATA | |
|---|---|
| Thread to be repaired | M5x0.8 |
| Inserts included | 15 pcs |
| Insert length | 1.5xD = 7.5 mm |
| Drill bit | Ø5.2 mm |
| Tap | STI M5x0.8 HSS-G |
| Insert material | stainless steel |
| Manufacturer | Varel |
| Product code | 13963 |
The M5 thread repair kit restores a worn or stripped tapped hole M5x0.8 in place, without drilling out for a larger screw. The kit includes a drill bit, STI tap, installation tool, tang break-off tool, and 15 stainless steel inserts with a length of 1.5xD.
Contents of the M5 thread repair kit
Four tools and a set of inserts in a case
Ø5.2 mm drill bit
HSS, DIN 338 – 1 pcs
M5 STI tap
HSS-G – 1 pcs
M5x0.8 inserts
1.5xD, stainless steel – 15 pcs
Installation tool
tool steel – 1 pcs
Punch
breaks off the tang – 1 pcs
The inserts are the only consumable component. Once they run out, only M5x0.8 1.5xD inserts need to be purchased — the tools in the case will handle dozens more repairs.
Technical data for the STI tap and 1.5xD insert
Dimensions of both kit components
| STI M5x0.8 TAP | |
|---|---|
| Thread to be repaired | M5x0.8 |
| Thread pitch P | 0.8 mm |
| Thread diameter B | 6.0 mm |
| Overall length L1 | 66 mm |
| Flute length | 19 mm |
| Square drive | 5.0 mm |
| Material | HSS-G (ground thread) |
| Tap drill hole | Ø5.2 mm |
| Hole type | through and blind |
| M5x0.8 1.5xD INSERT | |
|---|---|
| Restored thread | M5x0.8 |
| Thread pitch P | 0.8 mm |
| Height after installation | 7.5 mm (1.5xD) |
| Thread count | approximately 6.9 |
| Free-state outside diameter | 6.25–6.8 mm |
| Material | stainless steel |
| Installation version | with tang |
| Recommended drill bit | Ø5.2 mm |
| Thread direction | right-handed |
The 1.5xD length, or 7.5 mm, is suitable for steel, stainless steel, cast iron, and aluminum. Almost seven coils transfer the screw load across the entire thread in the hole, and the stainless steel wire does not seize against the steel screw even after years of service.
How the M5x0.8 thread insert works
Comparison of a directly tapped thread and a thread with an insert
| What changes in the threaded hole | Standard M5 thread | Thread for insert |
|---|---|---|
| Tap drill | 4.2 mm | 5.2 mm |
| Thread cut in the parent material | 5.0 mm | 6.04 mm |
| Tap | M5 | M5 STI |
| Bolt after repair | M5 | M5 |
The insert is a coil wound from diamond-section wire — customers also ask for it as a thread repair sleeve or spring. The outer point of the diamond engages the oversized thread in the material, while the inner surface provides a standard thread for the screw M5x0.8.
The oversize comes from the wire thickness: 0.65 × 0.8 = 0.52 mm. The wire lies on both sides of the profile, so the thread in the material increases to 5 + 1.3 × 0.8 = 6.04 mm. Hence the tap M5 STI with a 6.0 mm thread and the drill bit 5.2 mm instead of 4.2 mm for a standard M5 thread.
The joint requires no adhesive or locking compound. The free insert measures 6.25–6.8 mm, making it wider than the tapped hole; the tool winds it tighter during installation, and once released, the coils expand against the thread in the material.
Installing an insert in an M5 hole – sequence of operations
Four steps from drilling to a finished threaded hole
M5 thread repair step by step
1Drilling
Diameter: Ø5.2 mm
2Tapping
Tap: M5 STI
3Screwing in the insert
With the installation tool, a quarter turn below the surface
✓Breaking off the tang
Finished thread: M5x0.8
Tap with oil, reversing the tool after each full turn
▲
Blind hole – tap deeper than the insert
The 1.5xD insert occupies 7.5 mm of thread, but the STI tap has a chamfer that does not cut a full profile at the bottom. Tap at least 2 mm deeper and blow out the chips before installing the insert. Use a magnet to remove the tang after breaking it off with the tang break-off tool — leaving it in place blocks the screw.
The M5 STI tap has an overall length of 66 mm and a flute length of 19 mm, allowing it to reach recessed holes as well. Guide it with a tap wrench fitted to the 5.0 mm square.
Measure screw length from the material surface, not from the bottom of the hole. The 1.5xD insert occupies 7.5 mm, which is the usable engagement length — a screw a few millimeters longer will bottom out and fail to clamp the joined parts.
M5 thread repair – customer questions
Selecting tools, drill bit and insert length
Frequently asked questions
No. The hole for the insert must have a 6.04 mm thread, which is 1.04 mm larger in diameter than a standard M5 thread. Only the STI tap supplied in the kit, marked 6.0 mm, cuts this thread.
Ø5.2 mm — the drill bit is included in the kit. A standard M5 thread requires a 4.2 mm hole, so the hole diameter increases by 1 mm. The stripped thread usually falls within this allowance, and the hole does not need to be drilled out beforehand.
About 2 mm deeper than the insert height, for a total of approximately 9.5 mm. The extra depth accommodates the incomplete threads cut by the tap chamfer and the chips that collect at the bottom.
Yes. The inside of the insert restores the M5x0.8 thread with a fit class suitable for standard screws. Initial insertion may be slightly harder until the tang is broken off with the tang break-off tool.
Fifteen stainless steel 1.5xD inserts. The tools do not need replacing, so once the inserts are used up, only M5x0.8 inserts need to be purchased.
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Shipping
All orders are delivered by courier company GLS. For orders exceeding 369 PLN gross shipping is FREE
| 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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