December 29, 2020
Though Chris said groove, I read his drawing as a dimple! As this is a classic engineering problem with 2D drawings, may be worth mentioning the answer. Its to provide two or more views of the object, which together provide all the information needed to derive the 3D shape. Basically, draw what the object looks like from three sides, like plan, front and side: Actually this object only needs two views to show Chris said and meant groove. Far more to Technical Drawing and Draughtsmanship than...