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Printer calibration coupons: hole, pin, nut-trap, T-slot tongue and bearing-pocket gauges

How do I calibrate my 3D printer so holes and shafts fit the files in this library? · Hardware · basis: Every file on this site assumes: pivot hole = pin + 0.2, press fit = pin − 0.05, bearing pocket = OD + 0.2 (OD + 0.3 above 20 mm), nut trap = AF + 0.3, T-slot tongue 5.8 in a 6 mm slot. These coupons find your printer's offset so those assumptions hold

Long Earth Society build part. Print these first; every LES part assumes these fits. The engines · all LES parts

sizes
7 in table

Notes

  • Print the Ø3 hole gauge; push a 3 mm dowel pin through each: the first that slips freely is your 'clearance', the last that needs a tap is your 'press'. If 3.2 slips and 3.0 presses, your printer matches the library and nothing needs changing. If it takes 3.4 to slip, set a horizontal hole compensation of +0.2 mm in the slicer (or scale holes in CAD).
  • Pin gauge: the 3.0 pin should enter a 623 bearing bore with finger pressure; if only 2.9 does, external features print fat: set XY compensation −0.05. Nut gauge: the M3 nut should push into the 5.8 AF trap and not fall out of 5.6. Tongue gauge against real 2020: 5.8 slides, 6.0 binds. Pocket gauge: a 608 presses into 22.2 with a thumb and holds.
  • Do this once per printer and filament (PETG shrinks less than PLA, ABS more); write the two numbers (hole offset, XY offset) in your slicer profile. After that every STEP and STL on xemstudio.com fits as drawn, and an AI agent designing around these sheets can use the stated clearances without guessing.

Sizes

gaugewhat it testspass condition
hole 2.8–3.6Ø3 pivots / M3 clearance3.0 press, 3.2 slip, 3.4 clearance
hole 4.8–5.6Ø5 shafts5.0 press, 5.2 slip
hole 7.8–8.6Ø8 shafts8.0 press, 8.2 slip
pin 2.8–3.2 / 4.8–5.2printed pins into bearings3.0 / 5.0 enters finger-tight
nut trap M3/M4captive nuts5.8 / 7.2 AF snug
tongue 5.6–6.0T-slot brackets5.8 slides in 2020
pocket 10/16/22623 / 625 / 608 pockets+0.2 thumb press

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

WikipediaEngineering tolerancewebCC BY-SA 4.0 (text)
PrusaKnowledge base: XY size compensationwebPrusa KB verify
Long Earth SocietyEngine and rig buildsweb, videoLES site

Free files

★ Free files 8 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json

hole-gauge-m3-2-8-to-3-6hole gauge for Ø3 pins/screws: 2.8–3.6 in 0.1 steps (find press, slip and clearance)STEP · STL
hole-gauge-m5-4-8-to-5-6hole gauge for Ø5 shafts: 4.8–5.6STEP · STL
hole-gauge-m8-7-8-to-8-6hole gauge for Ø8 shafts: 7.8–8.6STEP · STL
pin-gauge-2-8-to-3-2printed pin gauge 2.8–3.2: which prints to a true Ø3 hole in a bearing?STEP · STL
pin-gauge-4-8-to-5-2printed pin gauge 4.8–5.2 (625 bearing bore test)STEP · STL
nut-trap-gauge-m3-m4nut-trap gauge: M3 at 5.5/5.7/5.9 AF, M4 at 7.0/7.2/7.4STEP · STL
extrusion-tongue-gauge-6mmT-slot tongue gauge: 5.6 / 5.8 / 6.0 mm tongues for a 6 mm slotSTEP · STL
bearing-pocket-gauge-623-625-608bearing pocket gauge: Ø10.0/10.2/10.4 (623), Ø16.0/16.2/16.4 (625), Ø22.0/22.2/22.4 (608), 6 deepSTEP · STL

Plain text: sheet.txt · JSON: /api/geometry?object=printer-calibration-coupons

Printer calibration coupons: hole, pin, nut-trap, T-slot tongue and bearing-pocket gauges, isometric render of a generated part
Render of hole-gauge-m3-2-8-to-3-6 from the free STEP; not to scale.

Fits with

Ball bearings, 683 to 6210 and flanged F6xx (ISO 15), isometric render of a generated part
Ball bearings, 683 to 6210 and flanged F6xx (ISO 15)44 sizes★ 44 files
Dowel pins, 2–6 mm (ISO 2338 / DIN 6325), isometric render of a generated part
Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)5 sizes★ 23 files
Hex nuts, M2–M8 (ISO 4032), isometric render of a generated part
Hex nuts, M2–M8 (ISO 4032)7 sizes★ 7 files
T-slot attachments: slide-in and drop-in T-nuts, corner brackets, gussets, end caps, slot covers, feet, hole plates, isometric render of a generated part
T-slot attachments: slide-in and drop-in T-nuts, corner brackets, gussets, end caps, slot covers, feet, hole plates7 sizes★ 46 files
Heat-set threaded inserts, M2–M6 (for 3D prints), isometric render of a generated part
Heat-set threaded inserts, M2–M6 (for 3D prints)6 sizes★ 6 files
Can-engine printed kit: can caps, diaphragm clamps, displacer guides, crank stands, CD/platter hubs, syringe cradles, isometric render of a generated part
Can-engine printed kit: can caps, diaphragm clamps, displacer guides, crank stands, CD/platter hubs, syringe cradles7 sizes★ 23 files

Questions

What tolerance do the files on this site assume?

Pivot holes pin + 0.2 mm, press fits pin − 0.05, bearing pockets OD + 0.2 (0.3 above 20 mm), nut traps AF + 0.3, T-slot tongues 5.8 mm. Print the gauges once to confirm your printer lands there.

My holes print too small; what do I change?

Measure which gauge hole slips over a 3 mm pin; the difference from 3.2 is your offset. Set it as hole/horizontal compensation in the slicer (+0.1 to +0.3 is typical for PLA on a 0.4 nozzle).

Why do printed holes come out undersize?

Extrusion width rounding on curves, plastic shrink and the slicer's arc approximation all push material inward; outside features come out fat by a similar amount. A one-time XY compensation fixes both.