日本語

Printed from Kezuriba (kezuriba.net/en/threads/m14/)

M14×2

ISO metric coarse thread

Nominal diameter 14 mm, pitch 2 mm. Tap makers recommend slightly different drill sizes, so they are listed side by side.

Tap drill, rule of thumb (d − P)
12.00 mmMaker recommendations below
Minor diameter D1 range (6H)
11.835 – 12.21 mmKeep the hole inside this range[4][5][3]
Pitch diameter d2 (basic)
12.701 mmd2 = d − 0.649519P
M14 basic profile and dimensions (schematic)
external thread (bolt)major dia. d = 14pitch dia. d2 = 12.701minor dia. D1 = 11.8356H range 11.835–12.21 (tap drill target)P = 2H160°

Thread angle 60°. H1 (basic thread engagement) = 0.541266P = 1.083. The pitch diameter is where the thread ridge and groove are equally wide. For cutting taps, pick a drill that lands inside the 6H tolerance of the minor diameter D1. Enlarged to show the shape; proportions are not to scale.

⌀Tap drill size for cutting taps (maker recommendations)

For internal thread class 6H. Values as given in each maker’s technical data (mm).

MakerRecommended drillNotesSource
OSG12min. 11.84, 6H max. 12.21
previous edition recommended 12.1 (changed in the current edition)		[3]
Nachi (Nachi-Fujikoshi)12high-performance drill 12.1[5]
Yamawa12.1[4]
Calculate tapping RPM for this size →

Forming (roll) tap drill sizes differ by maker and product line; see the Japanese page for the table.

⌇Basic dimensions

Nominal (major) diameter d14
Pitch P2
Pitch diameter d2, D212.701
Basic minor diameter D1 (nut), d1 (bolt)11.835
Fundamental triangle height H = 0.866025P1.732
Basic engagement H1 = 0.541266P1.083

Basic dimensions are theoretical values without tolerance. Try other pitches with the thread dimension calculator.

⬡Bolt and nut sizes

ItemmmConfidence
Hex bolt width across flats s (ISO-based JIS, main body)21Agrees in 2+ sources[10][11]
Hex bolt width across flats s (old JIS, annex)22Agrees in 2+ sources[12][10]
Hex nut width across flats s (ISO-based JIS, main body)21Agrees in 2+ sources[10][13][14]
Hex nut width across flats s (old JIS, annex)22Agrees in 2+ sources[15][10]
Hex nut height m (style 1, max.)12.8Agrees in 2+ sources[13][14]
Socket head cap screw head diameter dk (max.)21Agrees in 2+ sources[16][17][18]
Socket head cap screw head height k (max.)14Agrees in 2+ sources[16][18]
Hex socket size s (hex key size)12Agrees in 2+ sources[16][17][18][10]
Hex socket depth t (min.)7Agrees in 2+ sources[16][17][18]

Note: for M14 the ISO-based and old JIS across-flats sizes differ (21 vs 22). Check before choosing a wrench for Japanese hardware.

⊙Clearance holes and counterbores

ItemmmConfidence
Clearance hole d′ for socket head cap screws16Agrees in 2+ sources[16][20]
Counterbore diameter D′ for socket head cap screws23Agrees in 2+ sources[16][20]
Counterbore depth H″ (head sits below the surface)15.2Agrees in 2+ sources[16][20]
Counterbore depth H′ (head slightly proud)12.8Agrees in 2+ sources[16][20]
Clearance hole, class 1 (JIS B 1001)151 source (reference)[19]
Clearance hole, class 2 (JIS B 1001)15.51 source (reference)[19]
Clearance hole, class 3 (JIS B 1001)16.51 source (reference)[19]
Spotface diameter for hex bolts and nuts (JIS B 1001)321 source (reference)[19]

Socket-head values are from the reference table of JIS B 1176; clearance-hole classes are from JIS B 1001. The two standards give different clearance holes for some sizes.

≋M14 fine threads

SizeD1 range (6H)Recommended drill (cutting tap)
M14×1.512.376 – 12.676OSG 12.5 / Nachi (Nachi-Fujikoshi) 12.5 / Yamawa 12.6

📚Sources

Most sources are Japanese technical documents from the tap and fastener makers.

  1. iwata-fa.jp https://www.iwata-fa.jp/contents/assets/pdf/technicaldata/2022_tec_other_13.pdf
  2. nbk1560.com https://www.nbk1560.com/images/ja-JP/product/technical_data/meternezi_NBK/meternezi_NBK_1.…
  3. osg.co.jp https://www.osg.co.jp/media_dl/technical/file/drill_hole_size.pdf
  4. yamawa.com https://www.yamawa.com/Portals/0/images/download/holesize/jp/technical-contents-15.pdf
  5. nachi-fujikoshi.co.jp https://www.nachi-fujikoshi.co.jp/dcms_media/other/2501-12.pdf
  6. osg.co.jp https://www.osg.co.jp/media_dl/technical/file/p_8.pdf
  7. yamawa.com https://www.yamawa.com/Portals/0/images/download/holesize/jp/technical-contents-16.pdf
  8. baer.tools https://baer.tools/en/blog/core-hole-dimensions-for-screw-taps-everything-you-need-to-know
  9. orist.jp https://www.orist.jp/technicalsheet/98015.PDF
  10. eg.aktio.co.jp https://www.eg.aktio.co.jp/wp-content/uploads/R3T_1-5_TONE_bolt_nimen.pdf
  11. jp.misumi-ec.com https://jp.misumi-ec.com/pdf/fa/2015/p1_2367.pdf
  12. tsurugacorp.co.jp https://www.tsurugacorp.co.jp/img/usr/pdf/B00000.pdf
  13. jp.misumi-ec.com https://jp.misumi-ec.com/pdf/fa/2015/p1_2369.pdf
  14. fabory.com https://www.fabory.com/en-GB/p/01103140001
  15. static.nbk1560.com https://static.nbk1560.com/images/ja-JP/product/technical_data/rokkaku_nut_NBK/rokkaku_nut…
  16. jp.misumi-ec.com https://jp.misumi-ec.com/pdf/fa/2015/p1_2363.pdf
  17. tsurugacorp.co.jp https://www.tsurugacorp.co.jp/img/usr/pdf/A00000.pdf
  18. farnell.com https://www.farnell.com/datasheets/11699.pdf
  19. static.nbk1560.com https://static.nbk1560.com/images/ja-JP/product/technical_data/boltana_zagurikei_NBK/bolta…
  20. nbk1560.com https://www.nbk1560.com/resources/other/article/technical-22-dimensions-of-holes-for-hexag…