Did they perform the CNC work using a regular Fusion 360 file?
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Pretty much! Most services (JLC included) will ask for a .step file and a dimensioned drawing calling out specific features like tapped holes or tight tolerances.
Unless you specify a tolerance / GD&T callout, most of the online CNC services I’ve seen will follow a blanket tolerance spec (usually ISO 2768) that establishes tolerance ranges based on feature and part size.
Now… I’m not sure how many of these online CNC services will actually pay attention to the tight tolerances called out on a drawing unless you specifically request a part inspection / report. I had a dimensional issue on my steerer block where the slot width was around 0.1mm (or .004") oversize, outside of the callout on my drawing and the +/- 0.05mm tolerance box I selected on JLC’s website. JLC’s suggestion was to add order notes requesting physical inspection + photos of tight features before parts were shipped out (lol). It seems like JLC is both (1) assuming their equipment and machining process are good enough to hit their tightest advertised tolerances without any special fixture/programming changes and (2) banking on customers not catching OOS parts.
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