Metric | Drill diameters for tapping threads | ||
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M1 - M10 | Thread pitch (P) | ![]() cutting tap |
![]() roll tap |
ø mm | mm | ø mm | ø mm |
1 | 0.25 | 0.75 | 0.90 |
1.6 | 0.35 | 1.25 | 1.40 |
1.8 | 0.35 | 1.45 | 1.65 |
2 | 0.40 | 1.60 | 1.80 |
2.2 | 0.45 | 1.75 | 2.00 |
2.5 | 0.45 | 2.05 | 2.30 |
3 | 0.50 | 2.50 | 2.80 |
3.5 | 0.60 | 2.90 | 3.20 |
4 | 0.70 | 3.30 | 3.70 |
4.5 | 0.75 | 3.80 | 4.15 |
5 | 0.80 | 4.20 | 4.60 |
6 | 1.00 | 5.00 | 5.50 |
7 | 1.00 | 6.00 | 6.50 |
8 | 1.25 | 6.80 | 7.40 |
Metric | Drill diameters for tapping threads | ||
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M11 - M64 | Thread pitch (P) | ![]() cutting tap |
![]() roll tap |
ø mm | mm | ø mm | ø mm |
9 | 1.25 | 7.80 | 8.40 |
10 | 1.50 | 8.50 | 9.30 |
11 | 1.50 | 9.50 | 10.30 |
12 | 1.75 | 10.30 | 11.20 |
14 | 2.00 | 12.00 | 13.00 |
16 | 2.00 | 14.00 | 15.00 |
18 | 2.50 | 15.50 | 16.80 |
20 | 2.50 | 17.50 | 18.90 |
22 | 2.50 | 19.50 | 20.80 |
24 | 3.00 | 21.00 | 22.70 |
27 | 3.00 | 24.00 | |
30 | 3.50 | 26.50 | |
33 | 3.50 | 29.50 | |
36 | 4.00 | 32.00 | |
39 | 4.00 | 35.00 | |
42 | 4.50 | 37.50 | |
45 | 4.50 | 40.50 | |
48 | 5.00 | 43.00 | |
52 | 5.00 | 47.00 | |
56 | 5.50 | 50.50 | |
64 | 6.00 | 58.00 |
Roll tap
A roll tap or forming tap usually has a longer life and works faster. It produces no chips, a stronger thread and is also suitable for blind holes. A disadvantage is the higher purchase price. In addition, much more machine power is required to let the forming tap do its job (approx. 50% higher compared to cutting tapping). Special attention is needed for the right lubricant because of friction and with a lot of heat development as a result.
Cutting tap
With a cutting tap - usually called a thread tap - the thread is cut by machining. A tap is usually made of HSS (High Speed Steel) and has sharply ground cutting teeth. A lubricant is also used for tapping. The supply of cutting oil and the removal of the chips takes place through the recessed grooves of the tap. A set of taps usually consists of: 3 taps for metric threads, 2 taps for gas threads, 1 tap for machine taps. There are taps for the generally used right-hand thread, but also for left-hand thread.
Lubricants
When tapping, a lubricant suitable for the material is used, which serves to lubricate and cool. Today there are excellent universal oils available, for example drilling oil, cutting oil, tap oil, even 3 in 1 in aerosol.
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