Smallest feature: what an FDM printer can still print

What sets the limit

In FDM printing we push molten material through a nozzle. Ours is 0.4 mm and the layer height is 0.2 mm, so a line is about 0.4 to 0.5 mm wide. The printer will not create anything narrower than that on its own. The line width and layer height are a hard limit, not a question of print quality.

Thicknesses are therefore counted in multiples of the line width. One pass is around 0.4 mm, two around 0.8 mm. Walls that do not land on these multiples are rounded, and the strength is unpredictable.

Rough minimums

• Wall: at least 0.8 mm, for a strong part 1.2 mm and more. More in the entry on wall thickness.
• Freestanding post or pin: at least 1.5 to 2 mm in diameter, otherwise it snaps off at the lightest touch.
• Hole: at least 1.5 mm. Smaller holes shrink in printing and would need drilling, which we do not do. For precise screw holes allow positive clearance, see tolerances.
• Text and patterns: stroke at least 0.8 mm and characters 5 to 6 mm high, see relief and text.
• Gap between parts: 0.3 to 0.5 mm if they are to be separate.

What happens to a smaller detail

A thinner feature is either left out or comes out only as an uneven line. The slicer may drop it entirely and the model ends up with a hole. When you shrink a model with the scale, detail is lost first, so check the thinnest spots before shrinking. It helps to enlarge the detail or keep the model bigger.

How we handle it in an order

After upload the model is genuinely prepared for printing and we calculate the price and the lead time from what will actually print. We do not fill in details below the limit on our own. If a thin feature is important, order one piece first and look at the photo from the start of the print. Small holes in the mesh of the model are repaired automatically, but we do not enlarge the shape.