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Description
Material HSS
Thread size M16 left
Number of pieces3 pcs
Tolerance 6H ISO2
Technical data for the M16 left-hand hand tap
| Technical data | |
|---|---|
| Thread Diameter d1 | M16 |
| Thread Pitch P | 2 mm |
| Overall Length l1 | 97 mm |
| Flute Length l2 | 28 mm |
| Shank Diameter d2 | 12.5 mm |
| Square Drive Width Across Flats a | 10 mm |
| Tap Drill Hole | 14.0 mm |
Roughing, intermediate, and finishing taps – how much material each removes
Division of work in the 1–2–3 set
The M16 x2 LH thread is formed in the wall of a hole with a diameter of 14 mm. The thread groove extends 1 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 three layers.
The drawing shows the entire set in operation. All three taps have the same shank and the same length. They differ in chamfer length: No. 1 has a taper spanning 7–10 threads, while No. 3 spans only 1–2 threads. The detail views at the hole wall show how the thread groove deepens after each tap.
| Tap | Chamfer | Material removed | How it works in the hole |
|---|---|---|---|
| No. 1 – roughing tap | long, 7–10 threads | approx. 60% | enters smoothly and establishes thread alignment |
| No. 2 – intermediate | medium, 3–5 threads | approx. 30% | screws into the previously cut threads and starts cutting only deeper in the hole |
| No. 3 – finishing tap | short, 1–2 threads | approx. 10% + sizing | turns easily and produces the full 6H profile |
How to identify the tap numbers in the set
The chamfer is the tapered end of the tap. No. 1 has the longest chamfer and No. 3 the shortest – the difference is immediately visible when they are placed side by side. No. 1 and No. 2 have shallower thread profiles; only No. 3 has the full profile. The number can also be identified on the shank: No. 1 has one ring, No. 2 has two, and No. 3 has none. Keep the set together and always start with the roughing tap.
How to tap an M16 LH hole – sequence 1, 2, 3
Hand tapping step by step
Thread M16 x2 LH in five steps
ØDrilling
Drill bit 14 mm
1Roughing tap
Removes approx. 60%
2Intermediate
Removes approx. 30%
3Finishing tap
Removes approx. 10%
✓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 16 mm minus pitch 2 mm gives 14 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 24 mm, or 1.5 times the thread diameter (1.5 x 16 mm, shown as 1.5D in the drawing). Drill the hole deeper than the thread. The clearance below the thread accommodates chips and the finishing tap chamfer.
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 and No. 3 – deepening and full profile
Unscrew the roughing tap and remove chips from the hole. Screw the intermediate tap by hand into the previously cut threads – it should engage them naturally. It turns easily at first and starts cutting only deeper in the hole. The finishing tap enters with almost no resistance and cuts the final portion of the profile only at the end. When it screws smoothly all the way in, the thread is ready – check it with an M16 LH screw.
M16 left-hand HSS hand tap DIN 352 – 3-piece set for demanding applications
The M16 left-hand hand tap set is a complete set of three tools for cutting internal left-hand threads with a diameter of 16 mm and a pitch of 2 mm. M16 left-hand HSS hand taps are used in heavy industrial machinery, lathe spindles, conveyor drives, and components where high loads and vibration require protection against loosening.
Key benefits of the M16 left-hand tap set
- 3-piece set (roughing, intermediate, and finishing taps) – progressive cutting of a large thread minimizes tool load and the risk of breakage
- M16 left-hand thread – used in machine tool spindles, tensioning screws, and high-torque mechanisms
- HSS high-speed steel – ensures durability when machining structural steels with tensile strengths up to 800 MPa
- Tolerance 6H according to DIN 352 – precise fit with left-hand nuts and screws
- Large diameter of 16 mm – for connections carrying substantial mechanical loads
The M16 left-hand hand tap set is suitable for heavy industry plants, machine tool service facilities, and mining machinery repair companies. Use a drill bit with a diameter of 14 mm to prepare the hole for an M16 left-hand thread. For large diameters, we recommend ample lubrication 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
Use a 14 mm drill bit for an M16 thread with a pitch of 2 mm. The hole diameter is the same as for a right-hand thread.
M16 left-hand threads are found in lathe spindles, conveyor tensioning screws, and mechanisms operating under heavy loads. They protect against loosening.
Use ample lubrication and reverse the tool every half turn. For left-hand threads, turn counterclockwise. Do not apply excessive axial force.
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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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