Guide · Fit Test Generator

How to measure your 3D printer's fits with one test print

Fit Test Generator makes one small coupon, about 136 × 49 mm, that measures how your printer fits parts together: the room a part needs to slide, the room it needs to press in, and how much smaller holes print than drawn. Print it, pick the tightest numbered step that fits on each piece, and save the results with your printer and filament. It is free, and you need no calipers.

Open Fit Test GeneratorSee examples

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What can you measure with Fit Test Generator?

One print, about 7 g of PLA with every piece. Makers print it when:

  • Lids, sliders and drawers jam or wobble on their printer.
  • Holes for screws, magnets or bearings print too small.
  • They change to a new filament, nozzle or layer height.
  • They want every NabiMakes tool to use their printer's real fits instead of starting values.

How do you measure your fits, step by step?

The tool walks you through three steps: Printer, Print and Results. Saving is the last thing you do in Results.

  1. 1. Choose your printer and filament

    Pick the printer and the filament you want to test. The coupon's steps are centred on that filament's fits. Turn off any piece you do not need, and choose the colour of the raised numbers.

    Fit Test Generator's Printer step: the printer and filament, the pieces of the coupon and the label colour, beside the coupon on the bed.
    The printer, the filament and the pieces.

  2. 2. Print the coupon

    Download the 3MF with every piece on one plate, or a file per piece. Print it exactly as you print fitted parts, with the same nozzle, layer height and walls. Have the smooth shank of a 3 mm and a 6 mm drill bit ready for the holes.

    The Print step: what to keep as it is while printing, the drill bits and Download.
    What to keep the same, and the download.

  3. 3. Pick the tightest step that fits

    On the sliding strip, find the tightest hex hole the loose hex slides through with a light push. On the press ring, find the tightest hole the pin presses into. On the hole comb, find the tightest hole each drill bit goes into. Pick each step's number; nothing is picked for you.

    The Results step: a row of numbered steps for the sliding strip, the press ring and each row of holes.
    A row of steps for each piece.

  4. 4. Save your fits

    Your fits shows what you picked against the values the tools use now. Save to your printer keeps them with that printer and filament, dated, with the nozzle and layer height. Every tool's checks and holes use them from then on.

    Results with a step picked on every piece, and Your fits with the new values.
    Your fits, ready to save.

Which coupons can you start from?

Each example opens in Fit Test Generator as a new design, beside your own.

  • The full coupon

    Every piece on one plate: the sliding strip, the press ring and the hole comb.

    • Sliding, press and holes
    • About 136 × 49 mm
    • Free
    Open in Fit Test Generator

  • Holes only

    Only the hole comb, for screws, magnets and bearings that go into printed holes.

    • 3 and 6 mm holes
    • Drill-bit shanks
    • Free
    Open in Fit Test Generator

  • Sliding and press fits

    The sliding strip and the press ring, for lids, drawers and pins between printed parts.

    • Hex strip
    • Pin ring
    • Free
    Open in Fit Test Generator

Print the coupon with the settings you print fitted parts with: the results hold for those. It prints flat and needs no supports. If you change the nozzle or the layer height later, the tools keep your fits and remind you to print the coupon again.

FilamentLayer height to startThinnest wallSupportsNotes
PLA0.2 mm0.8 mmNoneThe usual choice; the coupon's steps centre on PLA's starting fits.
PETG0.2 mm0.8 mmNoneStarts with more room than PLA; test it on its own coupon.

Tips for an honest reading

  • Let the coupon cool fully before you test it: warm plastic fits looser.
  • Leave the slicer's hole and elephant-foot compensation as it is after the test, so nothing is corrected twice.
  • Use the smooth shank of the drill bit, not the cutting end; a hex key is too wide across its corners.
  • Test once per printer and filament: the results suit every part you print with them after.
  • Before you print, check it on the view's bar: Dimensions shows its size, Measure the distance between two points, Section cuts it open and Layers steps through it as your printer will.

What if every step fits, or none does?

Every step fits
Results offers a coupon shifted tighter for that piece. Print it and pick again; nothing is saved until you do.
No step fits
Results offers a coupon shifted looser for that piece. Print it and pick again.
Save is not offered
Choose your own printer first: the generic printer keeps no fits. Every printed piece also needs a pick before you can save.
The results were gone after the visit
Without an account they last for the visit only. Log in before you save to keep them in your account.

Is Fit Test Generator free?

Yes. The coupon, the results and the download are free; downloading needs a free NabiMakes account, which also keeps your fits.

  • Free

    Free
    • Every piece of the coupon
    • Re-tests shifted tighter or looser
    • Your fits saved per printer and filament
    • 3MF and STL

Every setting, with its range and default

The coupon's steps follow your filament's fits, so only the pieces and the label colour are settings.

SettingRangeDefaultWhat it does
What the coupon tests
Sliding fitOn, offOnThe sliding strip: 8 hex holes and a loose hex, 0.05 mm per side apart.
Press fitOn, offOnThe press ring: 7 round holes and a loose pin, 0.05 mm per side apart.
Holes for steel partsOn, offOnThe hole comb: seven 3 mm and seven 6 mm holes, 0.1 mm apart, read with drill bits.
Labels
Label colour22 optionsNavyThe raised numbers' colour. In 3MF they are their own part, so they can print in a second filament.