Dimensioning Question

[DaveH]

Tolerances have two main purpose's
One is so the bits and pieces fit together where ever they are made and secondary the machinist making the part doesn't have to "nail it" - it is time consuming and hence expensive.
In the home workshop tolerances are not always critical because we can make the parts fit and time isn't the prime concern, except of course when it's tea time

 
DaveH