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How to Wring Gage Blocks

Guide · Updated October 5, 2026

Wringing is how gage blocks are joined into a stack: two lapped, extremely flat faces are slid together until they cling. Done right, the joint adds a film only a few hundredths of a micrometer thick (on the order of a microinch or less) — small enough that shop work ignores it, though calibration labs account for it. Done wrong, you get a stack that's off by dirt, heat, or a burr, and blocks that wear out early.

1. Let the blocks and the work reach the same temperature

Gage blocks are calibrated at 20 °C (68 °F). Steel grows about 6.4 µin per inch per °F (about 11.5 µm/m per °C). A 4" steel stack that's 5 °F warm from your hands is long by roughly 6.4 × 4 × 5 = 128 µin (0.000128") — more than the whole tolerance of most grades. Handle blocks by the edges or with clean gloves or tongs, keep handling time short, and let a stack sit on the plate to normalize before measuring.

2. Clean every face you'll wring

• Wipe off the rust preventive with a clean, lint-free wipe and the solvent your block maker recommends.
• A bone-dry face often wrings poorly; a trace of very light oil film helps. What you're removing is grit and heavy preservative, not every molecule of oil.
• Keep fingerprints off the measuring faces. Skin salts are a leading cause of rust spots on steel blocks.

3. Check for burrs and grit

Slide the faces together lightly. If they feel gritty, catch, or refuse to cling, stop: re-clean, and check for a burr. A light burr can be removed with a gage block stone (see care & wear blocks). Forcing a dirty or burred joint scratches both blocks.

4. Thick blocks: cross, press lightly, rotate

1. Lay one block across the other at about 90°, measuring faces together, centered.
2. Apply light, even pressure and rotate the top block into alignment.
3. You'll feel resistance build as they wring. Once aligned, they should cling firmly.

5. Thin blocks: slide onto a thick block, never twist

Thin blocks (the 0.050"–0.100" range and the thin metric sizes) can bend and take a set. Wring a thin block onto a thicker one, not onto another thin block. Start it overlapping the end of the thick block, then slide it on with light pressure spread along its length. Don't use the rotate method on thin blocks.

6. Build in a sensible order

• Use the fewest blocks that make the size. Every joint adds a chance for error.
• Wring the thin blocks to thick ones first, then join those sub-stacks.
• If your set has wear blocks, put one on each end with the same marked face out every time, so only that face takes the wear.
• Support long stacks with gage block holders or accessories. Don't hang weight off a wrung joint.

7. Take the stack apart the same day

Separate blocks by sliding them apart, not prying. Don't leave stacks wrung for long periods: joints left overnight can be hard to separate and invite corrosion. Clean each block, apply a thin coat of rust preventive, and put it back in its slot.

Common mistakes

• Measuring right after building the stack by hand (thermal growth).
• Wringing two thin blocks together, or twisting a thin block on.
• Skipping wear blocks on stacks that touch anvils or work, so the working blocks wear instead.
• Storing blocks wrung together or without rust preventive.

Gear for wringing and stacking

• HFS 36-piece inch gage block set: a compact inch set for shop and home-shop setups.
• Mitutoyo 516-938-26 112-piece metric set: a full metric set.
• Mitutoyo 0.050" steel square gage block: a single 0.050" block, handy as a wear block or replacement.
• Gage block deburring stones: for light burrs that stop blocks wringing.

General shop information only — follow your gage manufacturer's instructions and your quality system. As an Amazon Associate I earn from qualifying purchases; links marked "sponsored" may earn a commission at no cost to you.