Why a perfect model still fits badly
A printer lays down a bead of molten plastic that spreads a little. Outside surfaces therefore come out slightly large and holes come out slightly small, usually by 0.05 to 0.2 mm per surface, and more on the first layers, where the plastic is squashed against the bed. A 20.0 mm hole for a 20.0 mm pipe will not go on. Clearance pays for that error in advance.
Measure your own printer
Print the test bin on this page: 40 by 30 mm outside, 12 mm high, with 1.2 mm walls. Let it cool, then measure it with a caliper halfway up the wall, away from the first layers and away from the corners. Three readings tell you most of what you need. If the 40 mm side reads 40.15, your printer adds 0.15 mm to outside sizes in that material. If the inside reads 37.45 where 37.6 was asked for, openings lose 0.15 mm. If a wall reads 1.3 instead of 1.2, your extrusion is a little high and a flow calibration is worth doing before you adjust anything else. Repeat the test when you change material.
Starting values
- Snap clip on a rigid pipe: 0.3 mm in PLA, 0.2 mm in PETG, which flexes more and can grip tighter.
- Clip on a soft cable: 0.2 mm; never zero, because the jacket should not be crushed.
- Pocket for a hex bit that should drop in: 0.25 mm in PLA, 0.3 mm in PETG.
- Bin next to other bins on a grid: 0.5 mm off the outer size.
- Drawer organiser inside a drawer: 0.5 to 1 mm off the measured space in total.
- Guide hole for a drill bit: bit diameter plus 0.2 mm.
Adjusting from the first print
Change the clearance in steps of 0.05 or 0.1 mm, one step at a time, and reprint only a short test piece: a clip 5 mm wide or a three-pocket strip takes minutes. Too tight means the part needs force, whitens or cracks; add clearance. Too loose means it rattles or slides under its own weight; remove some. Small features need relatively more clearance than large ones, and holes printed lying sideways are tighter at the top, where the layers bridge. Print the test bin floor down at a 0.2 mm layer height; it needs no supports.
Outline drawing
Left: the test bin, top view, to scale. Right: schematic of a pin in a printed hole, gap exaggerated.
Parameters the generator will use
| Setting | Link parameter | Value |
|---|---|---|
| Model | model | drawer_bin |
| Outer width (X) | width | 40 |
| Outer depth (Y) | depth | 30 |
| Outer height (Z) | height | 12 |
| Wall thickness | wall | 1.2 |
| Floor thickness | floor | 1.2 |
| Compartments across (X) | cols | 1 |
| Compartments deep (Y) | rows | 1 |
| Divider thickness | divider | 1.2 |
All lengths are in millimetres. Outer size from these values: 40 x 30 x 12 mm.
Open the generator with these values
This model is free. One $7 licence key opens five more models. Get a licence key on Gumroad ($7)
The test bin uses the fitted drawer organiser bin, which is the free model: no licence key and no account are needed to download the STL. The models the starting values refer to (pipe and cable clip, hex bit holder, screwdriver rack, 42 mm grid bin and drill guide jig) need a licence key.