日本語

Printed from Kezuriba (kezuriba.net/en/threads/m12/)

M12×1.75

ISO metric coarse thread

Nominal diameter 12 mm, pitch 1.75 mm. Tap makers recommend slightly different drill sizes, so they are listed side by side.

Tap drill, rule of thumb (d − P)
10.25 mmMaker recommendations below
Minor diameter D1 range (6H)
10.106 – 10.441 mmKeep the hole inside this range[4][5][3]
Pitch diameter d2 (basic)
10.863 mmd2 = d − 0.649519P
M12 basic profile and dimensions (schematic)
external thread (bolt)major dia. d = 12pitch dia. d2 = 10.863minor dia. D1 = 10.1066H range 10.106–10.441 (tap drill target)P = 1.75H160°

Thread angle 60°. H1 (basic thread engagement) = 0.541266P = 0.947. 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
OSG10.25min. 10.11, 6H max. 10.44
previous edition recommended 10.3 (changed in the current edition)		[3]
Nachi (Nachi-Fujikoshi)10.2high-performance drill 10.3[5]
Yamawa10.4[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 d12
Pitch P1.75
Pitch diameter d2, D210.863
Basic minor diameter D1 (nut), d1 (bolt)10.106
Fundamental triangle height H = 0.866025P1.516
Basic engagement H1 = 0.541266P0.947

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)18Agrees in 2+ sources[10][11]
Hex bolt width across flats s (old JIS, annex)19Agrees in 2+ sources[12][10]
Hex nut width across flats s (ISO-based JIS, main body)18Agrees in 2+ sources[10][13][14]
Hex nut width across flats s (old JIS, annex)19Agrees in 2+ sources[15][10]
Hex nut height m (style 1, max.)10.8Agrees in 2+ sources[13][14]
Socket head cap screw head diameter dk (max.)18Agrees in 2+ sources[16][17][18][19][20]
Socket head cap screw head height k (max.)12Agrees in 2+ sources[16][18][19][20]
Hex socket size s (hex key size)10Agrees in 2+ sources[16][17][18][19][20][10]
Hex socket depth t (min.)6Agrees in 2+ sources[16][17][18][19][20]

Note: for M12 the ISO-based and old JIS across-flats sizes differ (18 vs 19). Check before choosing a wrench for Japanese hardware.

⊙Clearance holes and counterbores

ItemmmConfidence
Clearance hole d′ for socket head cap screws14Agrees in 2+ sources[16][22]
Counterbore diameter D′ for socket head cap screws20Agrees in 2+ sources[16][22]
Counterbore depth H″ (head sits below the surface)13Agrees in 2+ sources[16][22]
Counterbore depth H′ (head slightly proud)11Agrees in 2+ sources[16][22]
Clearance hole, class 1 (JIS B 1001)131 source (reference)[21]
Clearance hole, class 2 (JIS B 1001)13.51 source (reference)[21]
Clearance hole, class 3 (JIS B 1001)14.51 source (reference)[21]
Spotface diameter for hex bolts and nuts (JIS B 1001)281 source (reference)[21]

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.

≋M12 fine threads

SizeD1 range (6H)Recommended drill (cutting tap)
M12×1.510.376 – 10.676OSG 10.5 / Nachi (Nachi-Fujikoshi) 10.5 / Yamawa 10.6
M12×1.2510.647 – 10.912OSG 10.75 / Nachi (Nachi-Fujikoshi) 10.8 / Yamawa 10.85
M12×110.917 – 11.153OSG 11 / Nachi (Nachi-Fujikoshi) 11 / Yamawa 11.09

📚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/01103120001
  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. static.nbk1560.com https://static.nbk1560.com/images/ja-JP/product/technical_data/rokkaku_bolt_NBK/rokkaku_bo…
  19. mikipulley.co.jp https://www.mikipulley.co.jp/EN/Services/Tech_data/tech10.html
  20. farnell.com https://www.farnell.com/datasheets/11699.pdf
  21. static.nbk1560.com https://static.nbk1560.com/images/ja-JP/product/technical_data/boltana_zagurikei_NBK/bolta…
  22. nbk1560.com https://www.nbk1560.com/resources/other/article/technical-22-dimensions-of-holes-for-hexag…