Micro Miniature Taps
info | threads
| taps | drill sizes
The Unified National Miniature Thread Series (miniature metric thread) was accepted as a new thread series in 1958 and was intended for general-purpose use in instruments, miniature mechanisms, and for jewelry and watches. The use of this series is recommended for all new products in place of the old standard miniature and the many improvised thread sizes still in existence. We will continue to supply the ongoing demand for the old standard miniature screw threads.
The UNM thread series
has fourteen miniature metric thread sizes that are systematically
distributed from .30mm to 1.40mm in diameter and supplements the
Unified and American Thread Series that begins at .060 inch diameter.
The diameter-pitch combinations provide for maximum strength against
stripping and for excellent manufacturability and interchangeability.
Technical data contained
in this site is taken from Fed-Std-H28/5 and ASME B1.10M-1997.
Newman Tools offers thread cutting tooling in a wide range of sizes for the main two standard miniature thread series.
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.30mm (.0118) |
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.35mm (.0138) |
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.40mm (.0157) |
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.45mm (.0177) |
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.50mm (.0197) |
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.55mm (.0217) |
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.60mm (.0236) |
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.70mm (.0276) |
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.80mm (.0315) |
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.90mm (.0354) |
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1.00mm (.0394) |
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1.10mm (.0433) |
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1.20mm (.0472) |
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1.40mm (.0551) |
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Taps are available in either a special alloy high carbon tool steel or high speed steel. The heat treatment of high carbon, tungsten-vanadium tool steel provides for 25% to 30% greater torsion toughness than high-speed steel. They are effective and efficient even with some tough materials, but for high nickel and chromium alloys high-speed steel is recommended. Our standard taps are a 3 flute plug tap or a roll/form style. To prevent excessive breakage, careful alignment of the tap and the hole is essential. Extreme care must be exercised when using small taps, always rotating forward only a fraction of a turn and then backing off to break and clear the chip.
Special tap coatings are available. Please contact us.
| 3-Flute plug Taps | Form Taps |
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(inches)
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THREADS |
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SIZE |
UP TO 2/3 MAJ DIA * | 2/3 TO 1 1/2 MAJ DIA * | 1 1/2 TO 3 MAJ DIA * | ||||
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| 1.40 UNM |
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| 1.20 UNM |
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| 1.10 UNM |
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| 1.00 UNM |
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| 0.90 UNM |
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| 0.80 UNM |
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| 0.70 UNM |
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| 0.60 UNM |
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| 0.55 UNM |
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| 0.50 UNM |
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| 0.45 UNM |
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| 0.40 UNM |
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| 0.35 UNM |
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| 0.30 UNM |
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| 00-90 |
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| 00-96 |
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| 00-112 |
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| 000-120 |
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| 0000-160 |
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Because these small taps are fragile, it is recommended that 75% thread be adopted only for soft materials and short threaded holes. As the length of the hole increases, the percentage of thread should be decreased. The depth of the hole to be threaded (*) as a function of the major diameter is provided in three groups and each group has a minimum and maximum for tap drill size. The minimum diameter should be used for soft and ductile materials and the maximum drill diameter for harder and more difficult materials. In many cases the hole diameter does not correspond to a numbered drill, so the closest millimeter drill should be selected.
The tap drill sizes shown for form taps are only a recommendation as a starting point. Depending on the material being tapped and the depth of the tapped hole, the hole size may have to be slightly increased or decreased to obtain good thread form and good tap life.