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Hand tap M3 LH DIN 352/2 6H HSS Fanar
€7.44 tax inc.
Net price: €6.05
Description
Material HSS
Thread size M3 left
Number of pieces2 pcs
Tolerance 6H ISO2
Technical data for the M3 left-hand hand tap
| Technical data | |
|---|---|
| Thread Diameter d1 | M3 |
| Thread Pitch P | 0.5 mm |
| Overall Length l1 | 40 mm |
| Flute Length l2 | 10 mm |
| Shank Diameter d2 | 3.5 mm |
| Square Drive Width Across Flats a | 2.7 mm |
| Tap Drill Hole | 2.5 mm |
Roughing tap and finishing tap – how much material each removes
Division of work in the 1–2 set
The M3 x0.5 LH thread is cut into the wall of a hole with a diameter of 2.5 mm. The thread groove extends 0.25 mm into the wall. A single tap would have to cut the entire groove at once – by hand, this creates high resistance and a risk of breakage. The set divides this work into two passes.
The drawing shows the entire set in operation. Both taps have the same shank and the same length. They differ in their chamfer, the tapered tip: No. 1 has a chamfer spanning 8 threads, while No. 2 spans only 2 threads. The detail windows at the hole wall show how the thread groove deepens after each tap.
| Tap | Chamfer | Chamfer angle | Material removed | How it works in the hole |
|---|---|---|---|---|
| No. 1 – roughing tap | long, 8 threads | 5° | the main portion of the groove | enters smoothly and establishes thread alignment |
| No. 2 – finishing tap | short, 2 threads | 20° | the remainder, to the full profile | follows the cut threads and produces the full 6H profile |
How to distinguish the taps in the set
The chamfer on No. 1 is 4 times as long as the chamfer on No. 2 — the difference is immediately visible when you place them side by side. No. 1 has an incomplete thread profile; only No. 2 has the full profile. The number is also indicated on the shank: No. 1 has one ring, No. 2 has none. Keep the set together and always start with the roughing tap.
How to tap an M3 LH hole – sequence 1, 2
Hand tapping step by step
Thread M3 x0.5 LH in four steps
ØDrilling
Drill bit 2.5 mm
1Roughing tap
Chamfer 8 threads
2Finishing tap
Chamfer 2 threads
✓Finished thread
Tolerance 6H
Turning sequence: half a turn counterclockwise, a quarter turn clockwise | Between taps: remove chips from the hole
Start with the hole. The drill diameter is easy to calculate: thread diameter 3 mm minus pitch 0.5 mm gives 2.5 mm. An undersized hole is a common cause of a tap twisting off in the workpiece.
Through hole or blind hole – how deep to drill
The set taps both types of holes. In a through hole, the thread extends through the full material thickness. In a blind hole, cut the thread to 7.5 mm, or 2.5 times the thread diameter (2.5 x 3 mm, shown as 2.5D in the drawing). Drill the hole deeper than the thread. The finishing tap has a chamfer spanning 2 threads, so approx. 2 incomplete threads remain near the bottom. The extra depth below the thread accommodates them along with the chips.
No. 1 – the roughing tap establishes thread alignment
Fit the roughing tap into a tap wrench and position it perpendicular to the surface. Check the angle from two sides, for example with a square. This is a left-hand thread, so turn in the opposite direction to usual: half a turn counterclockwise, then a quarter turn clockwise. Reversing breaks the chip into short pieces — a slight crunch is normal. The first threads determine whether the thread will be straight.
No. 2 – the finishing tap produces the full profile
Unscrew the roughing tap and remove the chips from the hole. Screw the finishing tap into the cut threads by hand – it should engage them naturally. Continue turning with the same rhythm used for the roughing tap. The finishing tap removes the remaining material and cuts the groove to the full profile in tolerance class 6H. When it screws in smoothly all the way, the thread is complete – check it with an M3 LH screw.
M3 left-hand HSS hand tap DIN 352 – 2-piece set for precision left-hand threads
The M3 left-hand hand tap set is a specialized set of two tools for cutting internal left-hand threads with a diameter of 3 mm and a pitch of 0.5 mm. M3 left-hand HSS hand taps are used in precision optics, measuring instruments, and clock mechanisms where miniature rotating components require protection against loosening on their own.
Key benefits of the M3 left-hand tap set
- 2-piece set (roughing and finishing taps) – efficient cutting of small left-hand threads
- Miniature M3 left-hand thread – for applications in optics, watchmaking, and precision mechanics
- HSS high-speed steel – provides the cutting edge sharpness required for small diameters
- 6H tolerance according to DIN 352 – precise fit in micromechanisms
- Delicate construction – requires careful work with a micro tap wrench and a suitable lubricant
The M3 left-hand hand tap set is used in optical workshops, laboratories, and precision instrument manufacturing companies. To drill the tap hole for an M3 left-hand thread, use a drill bit with a diameter of 2.5 mm. Such a small diameter requires an exceptionally light touch and frequent reversal of the tool.
Tolerance 6H — metric thread tolerance classes
| Class | Accuracy | Application | Status |
|---|---|---|---|
| 4H / 4g | High | Precision connections, hydraulics | — |
| 6H / 6g | Standard | Machine building, general-purpose | SELECTED |
| 7H / 8g | Low | Large clearance, easy assembly | — |
6H = internal thread (nut, hole) | 6g = external thread (screw)
Frequently asked questions
For an M3 thread with a pitch of 0.5 mm, use a 2.5 mm drill bit. The hole diameter is the same for right-hand and left-hand threads.
M3 left-hand threads are found in precision optics, clock mechanisms, and measuring instruments. They protect miniature rotating components against loosening.
Use a micro tap wrench and reverse the tool every quarter turn. Remember the left-hand direction – counterclockwise. Apply oil with a needle.
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