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Everything numeric this course uses, on one page. Built to be printed and stuck above the printer. The published values are starting points for a 0.4 mm nozzle in PLA — the table at the bottom is where your own measured numbers go, and those override everything above.
| Overhang | Up to 45° from vertical, unsupported | At 45° each layer still has about half the layer below it underneath |
|---|---|---|
| Bridge | Under 5 mm spans cleanly | Filament stretched across the gap stays taut long enough to cool |
| Bottom edges | Chamfer 0.3–0.6 mm, never fillet | A chamfer is self-supporting; a fillet leaves the solid horizontally |
| Downward faces | Replace flat roofs with two 45° faces | A ridge prints without support where a flat ceiling cannot |
| Horizontal holes | Teardrop the top, or accept an oval | The top of a horizontal circle is a 90° overhang and sags |
| Wall thickness | 0.8 mm absolute minimum, 1.6–2.4 mm structural | Whole multiples of extrusion width fill with complete perimeters |
|---|---|---|
| Vertical pin | 5 mm diameter, or add a base fillet | Thin towers wobble under the nozzle and never cool in time |
| Vertical hole | 1 mm minimum, 2 mm to be comfortable | Smaller circles are swallowed by the extrusion width |
| Horizontal hole | 2 mm minimum | Sagging at the top eats a fixed amount regardless of size |
| Embossed detail | Wider than 0.9 mm; engrave instead where possible | A raised feature narrower than one bead cannot be printed at all |
| Heights that must mate | Whole multiples of layer height | Otherwise the slicer rounds them and the lip lands off-target |
| Press fit | 0.05–0.10 mm per side | Assembles with force and does not come apart again |
|---|---|---|
| Slip fit | 0.20–0.30 mm per side | Pushes together by hand, holds position, separates when wanted |
| Free fit | 0.40–0.50 mm per side | Rotates and slides after the plastic has relaxed |
| Hole diameter | Add 0.2–0.4 mm to nominal | Printed holes come out undersized as a matter of course |
| Clearance on a diameter | Twice the per-side value | The gap exists on both sides of the part |
Filled in from the test coupon. Reprint the coupon and redo this table whenever the material, nozzle, layer height or slicer profile changes.
| Press fit (tightest that goes in) | ______________ mm |
|---|---|
| Slip fit (hand pressure) | ______________ mm |
| Free fit (spins freely) | ______________ mm |
| Hole compensation (nominal minus measured) | ______________ mm |
| Extrusion width | ______________ mm |
| Layer height | ______________ mm |
| Printer, material, profile | ________________________________ |
Full links, with what each source is good for, on the resources page. Where sources disagree, the more conservative value is printed here.
Every claim on these pages links to its source. If a source looks wrong or out of date, check the resource list and tell your teaching agent — the course is meant to be corrected.