letter drill · nominal diameter

I
drill bit size.

A I bit measures 0.2720 in across (6.909 mm).

The inch decimal is the published nominal designation; millimetres are a conversion.

Diameter conversion cross-checked

Calibrated relative diameter · 1 in reference

I · letter

0.2720 in

6.909 mm

DesignationIletter

Inch decimal0.2720nominal

Metric conversion6.909millimetres

Where this size sits from 0 to 1 inch

I · 6.909 mm on a zero to 25.4 millimetre scale. Neighbor marks: 6.9 mm, 7 mm.

0 25.4 mm

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Where this bit is specified

What I is for.

I is the cutting-tap drill for the thread below— usually the reason this size gets looked up. Engagement is calculated from the basic 60° profile; open a thread for its published row, evidence, and limits.

Cutting-tap rows naming I CUT TAPS ONLY · CALCULATED ENGAGEMENT

5/16-24 UNF UNF · manufacturer-published row 74.8% calculated thread engagement

Measured neighbors

What sits beside I.

“Nearest” means nominal diameter only. It does not make a neighboring size acceptable for a tolerance, tapping, reaming, or fastener application.

Other naming systemsABSOLUTE DIAMETER DELTA

6.9 mmmetric 0.2717 inΔ -0.009 mm 7 mmmetric 0.2756 inΔ +0.091 mm 6.8 mmmetric 0.2677 inΔ -0.109 mm 17/64fractional 0.2656 inΔ -0.162 mm 7.1 mmmetric 0.2795 inΔ +0.191 mm

Same seriesNEAREST NOMINAL ROWS

Jletter 7.036 mmΔ +0.127 mm Hletter 6.756 mmΔ -0.152 mm

Source record

ASME.

The standard text is paywalled. Number and letter series are cross-checked against public manufacturer charts; exact standard edition/page verification remains a release gate.

Open source record

Idrill bit size.

What I is for.

What sits beside I.

ASME.

I
drill bit size.