M12x1.75 tap speeds and feeds

    A M12x1.75 tap feeds one pitch per turn: 1.75 mm per rev. With a general-purpose HSS tap, start near 570 RPM and 998 mm/min in 6061 aluminum, or 160 RPM and 280 mm/min in mild steel.

    ISO metric coarse thread · major Ø 12.00 mm · tap drill 10.2mm (10.20 mm) for a cut tap, 11.25 mm for a form tap.

    M12x1.75 tapping speeds by material

    Cut tap = general-purpose HSS tap. Form tap = OSG form (roll) taps. RPM rounded to 10; feed in mm/min = RPM × pitch. Start at the low end.

    M12x1.75 cut and form tap speeds
    MaterialCut SFMCut RPMCut mm/minForm SFMForm RPMForm mm/min
    Aluminum 6061 / 707570–90570–730998–1,27865–115530–930928–1,627
    Free-machining / mild steel (12L14, 1018)20–40160–320280–56050–115400–930700–1,627
    4140 alloy steel (annealed to <35 HRC)20–30160–240280–42050–85400–690700–1,208
    304 / 316 stainless10–2080–160140–28015–40120–320210–560
    Tool steel (A2, D2, O1, H13, P20)15–25120–200210–3508–2560–200105–350
    Gray / ductile cast iron15–30120–240210–420Not listedNot listedNot listed
    Brass / bronze60–100490–810857–1,418Not listedNot listedNot listed
    Titanium (6Al-4V, CP)5–1540–12070–2108–1560–120105–210
    Plastics and composites (acetal, nylon, G-10)50–70400–570700–998Not listedNot listedNot listed

    Not listed = no form-tap value in the cited tables (OSG lists no form tap for cast iron; brass and plastics are not in its form-tap table).

    Premium coated cut taps on a rigid CNC

    OSG's starting speeds for its premium HSS-E cut taps (A-Tap family and the titanium/stainless taps it names) are higher than the general-purpose row. Use them only with that class of tap and rigid tapping.

    M12x1.75 premium cut tap speeds (OSG)
    MaterialOSG rowSFMRPMmm/min
    Aluminum 6061 / 7075Aluminum alloys70–120570–970998–1,697
    Free-machining / mild steel (12L14, 1018)Carbon steels <35 HRC80–120650–9701,138–1,697
    4140 alloy steel (annealed to <35 HRC)Alloy steels <35 HRC35–65280–530490–928
    304 / 316 stainlessStainless 300 & 400 series <35 HRC15–75120–610210–1,068
    Tool steel (A2, D2, O1, H13, P20)Alloy, tool & die steels 30–40 HRC15–30120–240210–420
    Gray / ductile cast ironCast iron50–120400–970700–1,697
    Titanium (6Al-4V, CP)Titanium alloys <35 HRC15–20120–160210–280

    Worked example: M12x1.75 in 6061 aluminum

    1. Surface speed: 70 SFM (low end of 70–90 for a general-purpose HSS tap).
    2. RPM = 3.82 × SFM ÷ D = 3.82 × 70 ÷ 0.47 ≈ 570 RPM (D = 12 mm = 0.47 in; or RPM = 1000 × 21.3 m/min ÷ (π × 12)).
    3. Feed per rev = pitch = 1.75 mm.
    4. Feed = RPM × pitch = 570 × 1.75 = 998 mm/min (39.3 IPM).

    G84 tapping code for M12x1.75

    Rigid tapping, aluminum numbers from the example, metric (G21), depth 1.5 × D. Check your control's manual before running.

    Fanuc rigid tap (M29)

    (M12x1.75 TAP - RIGID)
G21 G17 G40 G80 G90
T5 M06
G54 G00 X0. Y0.
G43 H05 Z25. M08
M29 S570           (RIGID TAP MODE; M-CODE SET BY PARAMETER)
G98 G84 Z-18. R3. F998.
G80 M09
G91 G28 Z0.
M30

    Haas rigid tap

    G21 G00 G90 G54 X0. Y0.
G43 H05 Z3. M08
G84 Z-18. R3. F998. S570   (NO M03 NEEDED)
(PECK: ADD Q = PECK DEPTH; J2 = RETRACT 2X, SEE SETTING 130)
G80 G00 Z25. M09

    Floating / tension-compression holder

    Without rigid tapping, run G84 with the spindle on (M03 S570) and the same F998 feed, but hold the tap in a tension-compression holder: it absorbs the overrun when the spindle stops and reverses. Leave the holder room to float at the bottom, so program the depth a little short and follow the holder maker's setting.

    • Peck tapping (Q) clears chips in deep or blind holes in stainless and 4140; skip it in aluminum unless chips pack.
    • Left-hand M12x1.75-LH taps use G74 instead of G84.
    • If the control caps rigid-tap RPM, lower S and recompute F: F = S × 1.75.

    Notes for this size

    • M12x1.75 is in the size range most shops rigid tap every day. Run the low end of the table first, then raise speed in 10% steps while watching spindle load on the reversal.
    4140 alloy steel (annealed to <35 HRC)
    Prehardened 4140 (28–32 HRC) is at the top of this band: use the low end and 50–65% thread.
    304 / 316 stainless
    Work-hardens: never let the tap dwell or rub, and use a tap made for stainless. 60–65% thread cuts torque sharply.
    Tool steel (A2, D2, O1, H13, P20)
    Values are for annealed or prehardened stock. Tap before heat treat whenever you can; hardened tool steel needs a thread mill or a carbide tap.

    Hole and tools for M12x1.75

    Tap calculator, prefilled for M12x1.75M12x1.75 tap drill sizeTap drill chart

    Common questions

    What RPM for a M12x1.75 tap?
    RPM = 3.82 × SFM ÷ D with D = 0.47 in. With a general-purpose HSS tap that is about 570 RPM in 6061 aluminum (70 SFM) and 160 RPM in mild steel (20 SFM). Premium coated taps on a rigid CNC can run faster; see the second table.
    What is the feed rate for a M12x1.75 tap?
    Feed per revolution equals the pitch: 1.75 mm. Feed (mm/min) = RPM × 1.75, so at 570 RPM the feed is 998 mm/min.
    How fast can I run a M12x1.75 form (roll) tap?
    OSG lists 65–115 SFM for form taps in aluminum alloys, which is 530–930 RPM for M12x1.75. Form taps need a larger hole: about 11.25 mm (11.25 mm).
    What speed for a M12x1.75 tap in stainless steel?
    General-purpose HSS taps: 10–20 SFM, or 80–160 RPM at 140–280 mm/min. Keep the tap cutting and use 60–65% thread to cut torque.

    Nearby sizes

    Sources

    SFM ranges are copied from the tables above; RPM and feed are computed for M12x1.75 (D = 12 mm). Speeds are starting values: your tap maker's data, coolant and machine come first.

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