From the Loftsmith Workshop
Tolerance test plate: peg ladder, hinges, M8 thread, snap
Find out how tight your printer really fits before you commit to a big print. One small plate has a row of numbered holes with a peg to push through, two hinges, an M8 bolt and nut, and a snap key. Change the first gap and the step between holes to match your printer.
8 parts · 23 g · 129 × 60 × 32 mm
Ask for the sizes you want to tweak, e.g. “make the width adjustable”.
How to print it
Parts
- plate · PLA · Flat as modeled, bottom face on the bed
107 x 60 mm card holding the peg ladder (holes 0.1-0.5 mm over 6 mm), the fixed hinge knuckles and pins, and the snap-key socket. Prints as one object together with the two flaps (print group). About 15 g, 25 min.
- flap-0.3 · PLA · Flat in its window, printed in place with the plate
Print-in-place hinge flap with a 0.3 mm radial gap round its 3 mm pin. About 2 g.
- flap-0.4 · PLA · Flat in its window, printed in place with the plate
Print-in-place hinge flap with a 0.4 mm radial gap. About 2 g.
- peg · PLA · Standing on its 11 mm flange
6 mm test peg for the ladder; stem printed upright so it comes out round.
- snap-key · PLA · Lying flat, label up
Two-arm barbed key; the arms flex in the print plane so layers run along them. About 1 g.
- bolt · PLA · Standing on its hex head
M8 x 1.25 ISO basic profile, 16 mm thread, 13 mm hex head. About 2 g.
- nut-0.2 · PLA · Flat on a hex face
One dimple. Thread grown 0.2 mm radially over the bolt. About 1 g.
- nut-0.3 · PLA · Flat on a hex face
Two dimples. Thread grown 0.3 mm radially over the bolt. About 1 g.
Print settings
- Layer height
- 0.2 mm
- Walls
- 2
- Infill
- 15%
- Supports
- None
- Notes
- At 2 walls and 15% infill the whole set is about 24 g and 1 h 11 min (Loftsmith engine estimate, A1). For stronger threads and snap arms use 3 walls / 15%: about 30 g and 1 h 24 min. Print everything on one plate. Keep the brim off the plate and flaps so the 0.8 mm gap round each flap stays open. Us
Assembly
- Print all eight pieces in one job. The plate and its two flaps come off the bed as one piece.
- Free the hinges: put a fingernail in the notch at each flap's free edge and lift gently until it swings. Note which gap (0.3 or 0.4) frees cleanly and which needs force or stays fused.
- Try the peg in each ladder hole, smallest first. The first hole it goes into with a push is your press fit; the first where it drops in and turns freely is your sliding fit.
- Screw the one-dimple nut (0.2 mm) and the two-dimple nut (0.3 mm) onto the bolt by hand. The tighter nut that still runs the full length is your thread clearance.
- Push the snap key straight down into the socket until the barbs click into the side windows. To release it, squeeze both barbs in through the windows and lift.
- Use the results: on other sized-to-fit models, set the clearance or fit sliders to the tightest gap that still moved on your printer.
Good to know
- All fits, hinge swings, thread poses and the snap catch are checked in the Loftsmith engine as rigid geometry. Real results depend on your printer, filament and slicer, which is the point of printing it.
- The bolt and nut thread flanks lean 30 degrees from horizontal, as on any M8 profile. They are only 0.68 mm deep and usually print upright without supports, but the lower flanks may look slightly rough.
- PLA is brittle: the snap arm is sized for 1.5% strain at the default 0.8 mm catch, under half of PLA's 4% elongation. Repeated clicking may still crack it; print the key in PETG if you want to test it many times.
- Ladder values are total (diameter) gaps; hinge and thread values are radial gaps per side. Compare like with like when you copy them into other models.
- If you set both ladder sliders to their minimum (0.05 and 0.05), the ladder stops at 0.25 mm and its check reports that it no longer reaches a sliding fit.
- In the picture the 0.2 nut is shown started two turns on the bolt tip and the 0.3 nut lies beside it. Both run fully engaged in the engine check.
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