Design guidelines

Design for 3D Printing

Most parts that fail were lost at the CAD stage, not on the printer. These are the rules we check every quoted file against — wall thickness, holes, overhangs, spans and orientation — with the real numbers for the materials we run.

See the Numbers Get Your File Checked

Per-material limitsChecked on every quoteASTM-sourced data20+ materials

The three that matter most

Where Printed Parts Actually Fail

Layer direction

An FDM part is strong along its layers and weak across them. A bracket printed flat and the same bracket printed upright are not the same part. Tell us which way the load goes and orientation is chosen for it — or move to SLS or MJF, which are near-isotropic.

Walls that are too thin

Below the minimum wall a feature either does not appear or appears without strength. The floor is set by the process and the material, not by the CAD.

Overhangs and bridges

Past the overhang angle a surface needs support, and support leaves marks. Redesigning a 60° overhang to 45° is usually cheaper than finishing the scar it would leave.

Per material

Design Limits by Material

	PLA	PETG	ABS	Nylon PA12	CF Nylon
Minimum wall thickness	0.8 mm	0.8 mm	1.0 mm	1.2 mm	1.5 mm
Minimum hole diameter	1.0 mm	1.2 mm	1.5 mm	1.5 mm	2.0 mm
Overhang limit	55 ° from vertical	50 ° from vertical	45 ° from vertical	45 ° from vertical	40 ° from vertical
Unsupported bridge	30 mm	20 mm	15 mm	15 mm	10 mm

Rules that hold across materials

Five Things Worth Doing Every Time

Fillet the inside corners

A sharp internal corner is a stress riser and a crack start. A small radius costs nothing in CAD and buys real strength.

Design holes slightly undersize

Printed holes tend to come out a little tight. If the fit matters, print undersize and drill or ream to size — or tell us the fit and we will allow for it.

Give threads a real anchor

Printed threads in fine pitches rarely last. A heat-set insert or a tapped boss in a thicker wall is the durable answer.

Avoid large flat first layers

A big flat face on the bed is where warping shows first, especially in ABS. Break it up or orient the part so it is not the footprint.

Send STEP, not just STL

STEP keeps exact curves and dimensions. An STL exported coarse arrives faceted, and we cannot recover what the export threw away.

Say what it has to survive

Load, heat, chemicals, UV, cosmetic or not. Every decision above changes with the answer, and it is the one thing a CAD file cannot tell us.

Questions

Design Questions

What is the minimum wall thickness for 3D printing?

For FDM it depends on the material: 0.8 mm for PLA and PETG, 1.0 mm for ABS, and 1.5 mm for carbon-fibre nylon. Across processes, SLA holds the thinnest walls and the powder processes sit between — our process comparison lists all of them.

How steep an overhang can I print without support?

About 55° from vertical in PLA, 50° in PETG and 45° in ABS. Past that the surface needs support, and support leaves witness marks that have to be finished off.

What tolerance can I expect?

Published accuracies are ± 0.5 % for FDM, ± 0.3 % for SLS and ± 0.2 % for SLA. Those are proportional, so a 200 mm part carries more absolute deviation than a 20 mm one. If a specific feature must hold a tight fit, say so — it may be printed oversize and machined.

Which way should the part be oriented?

Whichever way puts the layers across the load rather than along the break. Orientation also decides which surfaces carry support marks and how the part sits dimensionally. Tell us the duty and we choose it; guess, and the part may be strong in the wrong direction.

Do you check my file before printing?

Yes — every quoted file is checked against these limits, and problems come back with the quote rather than after the part is made. If a change would make the part cheaper or stronger, we say so.

Go deeper

The Data Behind These Rules

Have an Engineer Look at It

Send the file and what the part has to do. The DFM check comes with the quote — including the changes we would make and why.

Get a Quote Design services