bejant replied whilst I was typing and we pretty much say the same thing, I will post my response anyway in case it helps.
jlondon53 wrote: ↑
Wed Apr 24, 2019 11:55 pm
To repeat, I want to create a 'part' or '3D image" by FIRST creating a properly dimension-ed 2D front, top, and side view drawing - just like the old days and convert 'that' to 3D perspective - NOT create a 2D drawing from an an imported and/or already created 3d part/image like shown in literally every tutorial I've run across. 'CAN' I do this in FreeCAD? 'CAN' I simply create a properly dimension-ed blue-print and simply go to a different workbench and have it automatically converted to a 3D rendering? Thanks in advance!
That is pretty much impossible, however in a simplistic sense, for simple cases, that is what Sketcher does in PartDesign WB. Create a fully constrained 2d sketch then "Pad" that to a solid.
You should be able to learn PartDesign workflow easily with your back ground. But rather than trying to make the 3d solid from one massively complex 2d drawing, think in terms of splitting your workflow into several more simplistic steps (which is what a feature is).
For a very simplistic example, if you want a cube with a hole through it, create a 2d sketch only containing a fully constrained square, then Pad that sketch to get the cube, then 2d sketch a fully constrained circle and "Pocket" from that circle sketch to create the hole. Of course in that simple example, you could have included the circle within a square in one sketch and "Pad" that one sketch, the result would be a cube with a round hole in it. However that circle must be fully within the square, if an edge of the square and circle where to touch or overlap, the Pad would have to fail as it would not definitively define the resulting solid.
Just work step by step with simple examples and you should very quickly understand the logic.
Generally FreeCAD like most modern CAD programs defines a real 3d thing, where as 2d CAD is just defining a "picture" of a real thing as viewed from some arbitrary direction hence is useless for any further interpretation (or calculation or FEM or Path for CNC or Mesh for 2d printing or ray tracing for high quality visualisation etc.) without a human except for simple 2d examples like CNC laser/water/oxy cutters cutting out plate or similar.
You can use FreeCAD Draft WB for "old fashioned" 2d CAD work, but to FreeCAD they are "real" 2d geometry objects sitting in 3d space.
The 2d TechDraw WB is for, as you say, extracting an old fashioned 2d drawing from a 3d object, to print it on paper or a PDF etc. as required typically for human visualisation, legal requirements like building approvals, or a simplistic universal way to "exchange" data so in that sense somewhat like an exchange format.
Anyway, spend a few minutes in PartDesign and I think you will quickly understand it. Note that you create a "body" (a single contiguous solid) by building it up from "features". E.G. the Body would be the cube with a hole through it, it would contain a first feature (a Pad to make the cube) and a second feature (a Pocket to create the hole through it)