Nut-trap gauge: M3 5.5 / 5.7 / 5.9 AF and M4 7.0 / 7.2 / 7.4 AF — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/nut-trap-gauge/  (CC BY 4.0)
Basis: Hex traps stepped from the ISO 4032 across-flats (M3 5.5, M4 7.0) in 0.2 mm steps
Catalog version: 2026-10-20

Sizes: see table below
- Every file on this site is drawn at exact size with no printing allowance; this gauge steps through sizes around the nominal so you can measure the allowance your process needs for one fit class, then apply it only to the features each object lists under Mating features.
- The gauge is an 80 × 24 × 5 mm plate with six hex traps on 13 mm pitch: M3 at 5.5, 5.7, 5.9 AF, 2.7 deep, and M4 at 7.0, 7.2, 7.4 AF, 3.5 deep.
- Press an M3 or M4 hex nut into each trap: the trap that holds it snug, minus 5.5 or 7.0, is your nut-trap allowance.

trap  af_mm  depth_mm
M3  5.5 / 5.7 / 5.9  2.7
M4  7.0 / 7.2 / 7.4  3.5

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Wikipedia: Engineering tolerance — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Engineering_tolerance
- Prusa: Knowledge base: XY size compensation — web — Prusa KB [verify license at link] — https://help.prusa3d.com/article/xy-size-compensation_125045
- Long Earth Society: Engine and rig builds — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/nut-trap-gauge/index.json
API: https://xemstudio.com/api/geometry?object=nut-trap-gauge