Nolo
Member
Don't confuse tolerances with clearances.Tighter Tolerances = More Accuracy
Looser Tolerances = More Reliability
What you say is true of clearances, not exactly tolerances (it's a little different with tolerances).
Tolerance is basically a measure of quality control. How different is each of the same part that comes off the assembly line? .0001mm? .001mm? .1mm?
Clearance is the measure of how much space is between moving parts. Some are very tight. Some are very loose. In general, the more space between parts, the more reliable, and the less space, the more accurate.
However, that is not always true, and thus not entirely applicable.
For instance, sometimes super-tight clearances go hand-in-hand with great reliability, as in the Suomi SMG (which could actually create a vacuum in its receiver, the clearances were so tight).
However, loose tolerances always create worse accuracy, and they have no benefits other than ease of manufacture.