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Hand Tap M20X1 LH DIN 2181/2 HSS Varel
13970
€32.37 tax inc.
Net price: €26.32
Description
Technical data for the M20x1 left-hand hand tap
| Technical data | |
|---|---|
| Nominal diameter d1 mm | M20 |
| Thread pitch P mm | 1 mm |
| Overall length l1 | 80 mm |
| Flute length l2 | 18 mm |
| Shank diameter d2 | 16 mm |
| Square drive size a | 12 mm |
| Tap drill diameter | 19 mm |
| Thread angle G | 60° |
Roughing tap and finishing tap – how much material each removes
Division of work in the 1–2 set
The M20x1 LH thread is cut into the wall of a hole with a diameter of 19 mm. The thread groove extends 0.5 mm into the wall. A single tap would have to cut the entire groove at once — by hand, this means 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 | screws into the previously cut threads and produces the full thread 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 M20x1 LH hole – sequence 1, 2
Hand tapping step by step
Thread M20x1 LH in four steps
ØDrilling
Drill bit 19 mm
1Roughing tap
Chamfer 8 threads
2Finishing tap
Chamfer 2 threads
✓Finished thread
Thread M20x1 LH
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 20 mm minus pitch 1 mm gives 19 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 50 mm, or 2.5 times the thread diameter (2.5 x 20 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
Back out the roughing tap and remove chips from the hole. Screw the finishing tap into the cut threads by hand – it should engage them on its own. Continue turning at the same rhythm as with the roughing tap. The finishing tap removes the remaining material and cuts the groove to the full profile. When it screws in smoothly all the way, the thread is complete – check it with an M20x1 LH screw.
M20x1 left-hand hand taps
M20x1 hand tap left-hand fine-thread HSS - a two-piece set of LH left-hand cutting hand taps for cutting type M 20x1 metric fine threads. The offered M20x1 hand taps with left-hand threads are manufactured by the internationally renowned Czech company Narex. The brand is well regarded by professionals primarily for the high quality of its tools and the use of the latest technologies and modern materials in their manufacture. This results from collaboration with various research institutions and the implementation of their findings in production.
The offered M20x1 hand taps left-hand fine-thread versions are manufactured according to DIN 2181 from modern high-speed steel (HSS). They are suitable for tapping through holes and blind holes in components made from materials classified as P1.2 – P1.3, including metals, unalloyed steels, bronze, brass, aluminum, copper, and hard plastics. The taps offer high resistance to demanding machining conditions, as well as cutting edge resistance to potential mechanical damage. They also enable highly productive and very accurate machining. The resulting threads have tolerance class 6H.
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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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