I am trying to 3D print two types of threaded holes: M2.5 and M3 using a Formlabs printer in my university. I would like to know what would be the approximate tolerances for hole diameter, major and minor diameters, in order to get a decent threaded profile. Theretically, the distance between the major and minor diameters is 0.433mm (ie., 0.866*0.5) for M3 and 0.389mm (ie., 0.866*0.45) for M2.5 threads. The bore diameter is 2.5mm for M3 and 2.05mm for M2.5 threads respectively. Since the actual bore diameter after printing would be slightly lesser, I would like to know what would be a reasonable tolerance to provide for these dimensions.
It would be great to know the answers for these specific threads, but it would also be helpful to know a general rule of thumb for designing any thread size.