Instant Quote does not ask you to pick a tolerance class. Upload a STEP and we price the geometry. If you also send a PDF print, we machine to the callouts on that drawing. If you don’t, we default to ISO 2768-mK from the CAD model.

What ISO 2768-mK means

ISO 2768 is the usual title-block default for dimensions that do not have an individual tolerance:

m (medium): ISO 2768-1 linear and angular tolerances. A 30 mm length is ±0.2 mm; a 4-inch length is about ±0.008".
K (medium): ISO 2768-2 geometrical tolerances (straightness, flatness, perpendicularity, and related form/orientation). Position and profile still need a callout on the print.

Full tables live on the Quality Guide.

When a print is worth it

Send a PDF when any of these apply:

Interference or press fits
Bearing bores, seal diameters, or locating dowels
GD&T (position, profile, datums)
Thread class, heat treat, or a finish that isn’t as-machined
Anything tighter than ISO 2768-mK on a specific feature

You don’t need to tolerance every dimension. Title-block ISO 2768-mK plus a handful of critical callouts is usually enough.

Tighter than the default

We routinely hold tighter than mK on features that need it — ±0.001" on critical diameters is common when the design supports it. Tighter bands cost more: extra setups, slower feeds, and more inspection. Put those dimensions on the print so we don’t guess.

What to upload

STEP (.step / .stp) — required for Instant pricing
PDF — optional print; same part number and revision as the STEP
JPG / PNG — fine for 2D when you don’t have a PDF

Files up to 50 MB. See the Drawing Standards Guide for views, dimensioning, and file naming.