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Movement · TMI (Seiko Instruments) · automatic

Seiko NH70 (TMI) movement

Seiko NH70 (TMI) is an automatic movement by TMI (Seiko Instruments): 27.4 mm1 across, 5.32 mm2 high, 242 jewels, beating at 21,600 bph2, 41 h3 of power reserve.

Sources checked · How we source numbers
TMI NH70: movement drawingTMI NH70, dial side, to scale: movement diameter 27.4 mm; casing diameter 27 mm; size 12‴; height 5.32 mm; hour, minute, second hand hole Ø — (unknown).movement Ø 27.4casing Ø 2712‴ as printed · Ø 27.4 = 12.15‴5.32SIDE · SECTION · height 5.32Ahour, minute, second hand hole Ø —DETAIL A · 10:1
TMI NH70, dial sideDrawing from data, not a photo · mm

NH70 at a glance

Diameter
27.4 mm1
Height
5.32 mm2
Jewels
242
Beat rate
21,600 bph2
Power reserve
41 h3
Accuracy
−20 to +40 s/day3
Lift angle
53°3

New to the terms? Read quartz vs automatic or watch movement types.

What fits the NH70

The figures a dial, hands or case must match for the NH70, as TMI prints them.

Casing diameter
27 mm3

What can replace the NH70

11 calibres of the Seiko NH / 4R / 7S group checked against the NH70: diameter, height, hand holes, date window, crown and dial feet. A verdict marked “not confirmed” lacks one of those figures for the NH70 or the other calibre.

Not published, so not checked in several comparisons:

  • hand holes for NH70, NH38, NH39, NH72, 4R35, 4R34 and 4R36
  • crown position for NH70, NH38, NH39, NH72, 4R35, 4R34 and 4R36
  • dial feet for NH70, NH38, NH39, NH72, 4R35, 4R34 and 4R36

  1. NH70 → NH38

    Drop-in· not confirmed
    • =diameterSame movement diameter: 27.4 mm.
    • =heightSame height: 5.32 mm.

  2. NH70 → NH39

    Drop-in· not confirmed
    • =diameterSame movement diameter: 27.4 mm.
    • =heightSame height: 5.32 mm.

  3. NH70 → NH72

    Drop-in· not confirmed
    • =diameterSame movement diameter: 27.4 mm.
    • =heightSame height: 5.32 mm.

  4. NH70 → 4R35

    Fits with changes· not confirmed
    • =diameterSame movement diameter: 27.4 mm.
    • =heightSame height: 5.32 mm.
    • ≠date4R35 has a date: a dial without a window hides it, and the crown gets a date-setting step.

  5. NH70 → NH35

    Fits with changes· not confirmed
    • =diameterSame movement diameter: 27.4 mm.
    • =heightSame height: 5.32 mm.
    • ≠dateNH35 has a date: a dial without a window hides it, and the crown gets a date-setting step.

  6. NH70 → 4R34

    Fits with changes· not confirmed
    • =diameterSame movement diameter: 27.4 mm.
    • ≠functions4R34 adds a 24-hour hand: it needs a dial and hand set made for it.
    • ≠date4R34 has a date: a dial without a window hides it, and the crown gets a date-setting step.

    Not published, so not checked: height for 4R34.

  7. NH70 → 4R36

    Fits with changes· not confirmed
    • =diameterSame movement diameter: 27.4 mm.
    • =heightSame height: 5.32 mm.
    • ≠date4R36 adds a day wheel: a date-only dial hides it, and the crown gets a day-setting step.
    • ≠date4R36 has a date: a dial without a window hides it, and the crown gets a date-setting step.

  8. NH70 → NH34

    Fits with changes· not confirmed
    • =diameterSame size in lignes: 12‴.
    • =heightSame height: 5.32 mm.
    • ≠functionsNH34 adds a 24-hour hand: it needs a dial and hand set made for it.
    • ≠dateNH34 has a date: a dial without a window hides it, and the crown gets a date-setting step.

    Not published, so not checked: a millimetre diameter for NH34.

3 more calibres in the group fit less well; compare any of them with the movement comparison.

Setting and servicing the NH70

The figures a watchmaker or a timegrapher needs for the NH70, as TMI prints them.

Lift angle
53°3
Accuracy (maker)
−20 to +40 s/day33 positions (dial up, 9, 6)
Power reserve
41 h3
Hacking seconds
Yes2
Hand winding
Yes4

Same family at TMI

How each differs from the NH70, worked out from the figures on its own page.

All NH70 figures

Every figure we hold for the NH70, with its source. Where sources disagree, each value is shown.

Size

Size in lignes
12‴2
Diameter
27.4 mm1
Casing diameter
27 mm3
Height
5.32 mm2

Running

Jewels
242
Beat rate
21,600 bph2
Power reserve
41 h3
Hands and functions
hours, minutes, centre seconds2
Hacking seconds
Yes2
Hand winding
Yes4

Accuracy and care

Accuracy (maker)
−20 to +40 s/day3
Lift angle
53°3

Origin

Made in
Japan or Malaysia2

Not published yet

  • Hand holes: only in TMI’s drawing; not read yet
  • Dial feet: only in TMI’s drawing; not read yet
  • Stem part number: not in the documents we read
  • Do not set the date: not published

Versions

NH70A3J01 · NH70A3MN03 · NH70A4J01 · NH70A4MN03[5]

NH70 questions

What is the lift angle of the NH70?

53°, as TMI prints it. Enter 53° on a timegrapher to read amplitude correctly for the NH70.

Source [3]

How accurate is the NH70?

TMI rates the NH70 at −20 to +40 s/day, measured under TMI’s own test conditions; a worn NH70 can run outside the −20 to +40 s/day range.

Source [3]

How long does the NH70 run when fully wound?

About 41 h from a full wind, per TMI.

Source [3]

Does the NH70 hack and hand-wind?

Yes, it hacks: the seconds hand stops with the crown pulled out. It can be wound by the crown.

Source [2][4]

What can replace the NH70?

From the published figures, the closest is the NH38: drop-in, not confirmed for every part, with 2 more in the same group. Same movement diameter: 27.4 mm.

More on movements

Sources

Documents checked · Report a wrong number

  1. 1Time Module Ltd. — TMI Watch Movement Specification and Drawing (Spec Sheet) NH70 · pdf · read
  2. 2Time Module Ltd. — Product Line-Up - Skeleton Mechanical (NH7): NH70/NH71/NH72 blocks · html · read
  3. 3Time Module Ltd. — TMI Technical Guide & Parts Catalogue NH70 · pdf · read
  4. 4Time Module Ltd. — TMI Operation Manual NH70 · pdf · read