pic: TerrorBytes 2015 Shooter Plate (Drawing)

[Madison]

Originally Posted by Monochron

Though I was able to lookup what "dimensioning to witness" means I don't know what it means to show witness marks.

You're dimensions are measuring between the the intersection of two lines on one end and the similar intersection at the other end. The point where the lines intersect is the witness. Solidworks has a drawing annotation for marking that witness on the drawing. It'll make it clearer to whomever is reading the drawing that the dimension measures intersection. Also, for what it's worth, that's sometimes not a very useful dimension.

Tolerances will depend on the desired end result, the material, etc. For any sort of decorative feature (lightening holes included), you probably don't need to go more than two decimal places. The title block tolerance specifies a default tolerance for dimensions that don't call them out explicitly.