Technologies
Industrial 3D Printing Tolerances
What tolerances to expect from FDM, MSLA, SLS, MJF, CFC and LPBF metal, how to dimension your drawing, and when CNC finishing is needed.
"What tolerances can you hold?" is the first question every engineering team asks, and the honest answer depends on the process, the material and the geometry. In short: as-built accuracy ranges from ±0.2% in LPBF metal and ±0.3% in MSLA, SLS and MJF (with a ±0.3 mm minimum) to ±0.6 mm (±0.75% above 100 mm) in FDM, and the dimensions that need more are brought to size with targeted CNC finishing. Here are the realistic numbers we use when quoting, and the rules for dimensioning a drawing meant for additive manufacturing.
Typical tolerances by process
Each process has a stated dimensional accuracy, which applies to well-designed geometry before any finish machining.
| Process | Typical tolerance | Notes |
|---|---|---|
| FDM (incl. high-performance polymers) | ±0.6 mm up to 100 mm, ±0.75% above | depends on material and layer height; 3 mm minimum wall thickness |
| MSLA | ±0.3 mm up to 100 mm, ±0.3% above | 50 μm XY pixels, 1 mm minimum wall thickness: the choice for fine detail and smooth surfaces |
| SLS (PA12) | ±0.3% (minimum ±0.3 mm) | 85–90% isotropy, consistent from batch to batch, 0.5 mm minimum feature |
| MJF (PA12, PA11, PP, TPU) | ±0.3 mm up to 100 mm, ±0.3% above | near-isotropic, 80 µm layers, 1 mm minimum wall thickness |
| CFC (continuous fiber) | assessed part by part in the quote | 0.8 mm minimum feature |
| LPBF metal | ±0.2% (minimum ±0.1–0.2 mm) | 20–60 µm layers, 0.75 mm minimum feature |
| CNC finishing on the printed part | down to IT7–IT9 grades on machined features | only where the drawing calls for it |
Process values on well-designed geometry: very large, thin or bulky parts deserve a dedicated review at the quote stage. For MJF and metal, lead times are stated in the quote.
Where dimensional error comes from
Dimensional error comes from four factors, and most of them can be controlled at the design stage.
- Thermal shrinkage: every polymer shrinks as it cools; machine profiles compensate for it, but bulky geometry shrinks more. In LPBF metal, rapid melting and cooling builds up residual stress, which is managed with uniform cross-sections and a stress-relief cycle after the build.
- Orientation: resolution differs in the build plane and along Z, so critical dimensions should lie in the plane.
- Geometry: unsupported thin walls, large flat areas and abrupt changes in wall thickness distort more than average.
- Post-processing: supports, bead blasting and other treatments shift dimensions by tenths of a millimeter, so critical dimensions are measured after the full cycle.
How to dimension a drawing for additive manufacturing
Dimension selectively: tight tolerances only where they matter, a general tolerance everywhere else.
- Tolerance selectively: applying ±0.05 mm to the whole part multiplies the cost with no benefit. Pick the 2–5 dimensions that are truly functional and leave the rest at the general tolerance.
- Separate printed from machined: best practice is to flag the features that can be finish-machined, so you get machine-tool tolerances only where you need them (when the hybrid route pays off).
- In metal, add machining stock: on the functional surfaces of an LPBF part, leave material on the drawing for finish machining to remove (metal 3D printing guide).
- Design fits with print clearance: allow 0.1–0.3 mm of clearance on holes and pins depending on the process, or draw holes slightly undersized and ream them.
- State the function, not just the number: knowing that a hole takes a bearing or an insert (hardware embedding) lets us guarantee the fit, not just the dimension.
Tolerances and material: high-performance polymers
High-performance polymers hold the same tolerances as standard FDM, provided they are printed in a heated chamber. PEEK and Ultem need chamber and nozzle temperatures well above those of standard materials, and semi-crystalline PEEK must also crystallize in a controlled way. That is why we run them on heated-chamber machines (VisionMiner 22IDEX V4) and hold ±0.6 mm up to 100 mm and ±0.75% above on these grades too, with CNC finishing when the drawing asks for more. The full comparison of grades is in our guide PEEK vs Ultem vs PPS.
Checklist before you send the CAD
Before you upload the CAD, have these five items ready.
- Critical dimensions identified (5 at most), each with an explicit tolerance
- Features that can be finish-machined flagged (and, in metal, surfaces with machining stock)
- Fits with their function stated (bearing, insert, sliding)
- Preferred material, or the requirements (temperature, chemicals, load)
- Quantity and delivery tier: Express 48–72 hours, Rapid 5 days or Economy 7+ days (for MJF and metal, lead times are in the quote)
With this information, your quote arrives within 24 business hours with the tolerance strategy already worked out, and if a dimension is unrealistic for additive manufacturing, we tell you before printing, not after.