I went back & read the DennisD explanation regarding choice of involute generation & clearance caveats. Perfectly fine for my purposes at present. I’m not making gears, just wanting to something more accurate for my assemblies. Some of the online services are Ok if your gear happens to match what they sell, but not very useful if you have something different. And some are just plain wrong.
Somewhat related, I found these YouTube videos, appear to be part of an engineering course saved online. Interesting tutorial & quite a thorough workflow. Apparently there are gears and there are gears. Seems like once you get into more critical gear parameters and/or particular pinion/gear relationships, other issues rear their head & need to be compensated for. He writes an explicit formula for involute & discusses pros/cons in that regard.
I suppose if you want ‘real’ gears you have to buy a plug-in module where all this is dealt with, or write your own code. I’m very thankful the individuals mentioned in this discussion took on the challenge.
Video Titles
Modeling an Equation Driven Involute Spur Gear in Solidworks
2014W ENGR380 Lecture16 Introduction to Gear, Part II