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Tommy Screw Dimensions (DIN 6304, M6 to M20)

Guide · Updated October 28, 2026

DIN 6304 covers tommy screws with a fixed bar for jigs and fixtures, thread M6 to M20, Form E (no pad) and Form F (with a DIN 6311 thrust pad). Lengths l1, head diameter d2, bar diameter d3, thrust point d4, pin length l2 and bar length l3 below agree across the Ganter DIN 6304 catalog sheet, the JW Winco DIN 6304 sheet and the Elesa+Ganter DIN 6304 catalog; d2, d3, d4, l2 and l3 also match the DIN 6304 standard table and the Metalcom listing. Pad sizes are from the DIN 6304 designation table. Skipped: the small point and bar-offset dimensions (column letters differ between sources) and weights. Check the current edition or your supplier for critical work.

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Step by step

Pick the thread: Choose M6 to M20 to suit the clamp force and the tapped hole in your fixture.
Pick the length: Each thread has two or three standard lengths l1; pick one that reaches the part with thread still engaged.
Read the bar: The fixed tommy bar has diameter d3 and length l3, which sets how much hand torque you can apply.
Check the point: Thrust point d4 (h11) with pin length l2 takes a DIN 6311 thrust pad.
Choose Form E or F: Form E has a bare thrust point; Form F comes with the matching DIN 6311 pad fitted.
Order it: Designate as DIN 6304 E M10 x 60 (form, thread, length l1).

DIN 6304 tommy screw dimensions (mm)

Columns: thread d1, standard lengths l1, head diameter d2, bar diameter d3, thrust point d4 (h11), pin length l2, bar length l3, DIN 6311 pad for Form F.

Thread d1 | l1 | d2 | d3 | d4 | l2 | l3 | Pad
M6 | 40, 50 | 12 | 5 | 4.5 | 10 | 50 | S12
M8 | 50, 60 | 14 | 6 | 6 | 12 | 60 | S16
M10 | 60, 70 | 18 | 8 | 8 | 14 | 80 | S20
M12 | 70, 80 | 20 | 10 | 8 | 18 | 100 | S25
M16 | 75, 90, 110 | 24 | 12 | 12 | 20 | 120 | S32
M20 | 75, 90, 110 | 30 | 16 | 15.5 | 28 | 140 | S40

Worked example: M10 fixture clamp

DIN 6304 F M10 x 60 has an 18 mm head with an 8 mm bar 80 mm long, an 8 mm h11 thrust point with a 14 mm pin, and a DIN 6311 S20 pad fitted. If 60 mm does not reach the part with at least 1 to 1.5 x d of thread engaged, step up to the 70 mm length.

Tommy screw vs thrust screw

DIN 6304 tommy screw: bar fixed in the head, tighten by hand, no tool needed.
DIN 6332 thrust screw: same point and pad fit, but you add your own knob, lever or wrench.

Common problems

Not enough clamp force: go up a thread size for a longer bar.
Bar hits the fixture: pick a longer l1 or move the screw.
Pad falls off: check the snap ring and h11 point size.

FAQ

What is a DIN 6304 tommy screw?

A clamping screw with a steel bar pressed through the head so it can be turned by hand without a wrench. The other end has a thrust point for a pad.

Form E vs Form F?

Form E has no thrust pad. Form F is supplied with a DIN 6311 thrust pad on the point.

Which thrust pad fits?

DIN 6311 S12 for M6, S16 for M8, S20 for M10, S25 for M12, S32 for M16 and S40 for M20.

Is the bar removable?

No. DIN 6304 has a fixed bar. Tommy screws with a loose, sliding bar are covered by DIN 6306.

What material?

Typically steel property class 5.8, blackened, with a hardened thrust point; pads are case-hardened steel.

Why are some columns missing?

We only list values that the standard text and several catalogs agree on. Bar-to-thread offsets and weights are left out.

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General shop information only — follow your drawing, tool maker's data and your quality system.