If I tap a 4mm hole with a metric tap, will a SAE bolt of similar size go in there or will it cross thread?

 

use some common sense, it will cross thread or just be loose.

 

how is that common sense? I know the holes have difference diameters but my question was whether the 2 systems use difference thread pitches.

If the pitch is the same, and the hole diameter is slightly off, I can just use some locktite when I thread the bolt in there.

 

Thats like feeding a Mogwai after midnight. SAE and Metric are real close, BUT not the exact same. It will cross thread, because of the pitch difference.

 

thank you, that's the simple answer I was looking for -- "the pitch is different"