T-slot tongue gauge 5.6 / 5.8 / 6.0 mm (6 mm slot) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/extrusion-tongue-gauge/  (CC BY 4.0)
Basis: Tongues stepped below the 6.0 mm slot opening of 20-series extrusion
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 a 60 × 30 × 3 mm plate with three tongues 20 mm long × 1.5 mm tall, 5.6, 5.8 and 6.0 mm wide, on 20 mm pitch.
- Slide each tongue into the slot of a 6 mm-slot extrusion: the widest one that slides, minus 6.0, is your tongue allowance (negative).

tongue  width_mm  length_mm  height_mm
1  5.6  20  1.5
2  5.8  20  1.5
3  6.0  20  1.5

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/extrusion-tongue-gauge/index.json
API: https://xemstudio.com/api/geometry?object=extrusion-tongue-gauge