Precise modeling in Blender: Finding Tangents between Circles

[@spectre.garden]

Thanks, this is helpful. I am just digging into PDT.

[@DiThi]

This is fantastic for minor tasks like what I frequently do. But for full CAD designs it's better to use an addon like CAD Sketcher.

[@blender3darchitect]

I think you should use both. Each one has specific uses in many design workflows.

[@DiThi]

@@blender3darchitect I agree, even though I do a bit too much _without_ addons.

[@Cyber_Kriss]

Wait... If you look closely, the created tangents are not connected to the circles. Is there a way to fix that ?

[@blender3darchitect]

You are right. If you look close, they don't touch. The problem is that Blender uses Polygons as circles. They are not curves. Since Polygons use straight edges with lots of segments, usually you won't have a perfect intersection point. The solution would be: 1. Use a Mesh Circle with lots of sides 64+ to increase the chance of an intersection. 2. Edit the point close to the tangent to make them intersect

Why is precision drawing just such an utter nightmare in Blender?

[@spectre.garden]

Because it was designed to be a polygonal modeling suite, not a CAD tool. The fact that the gap is being bridged with tools like we are being shown here, is something to celebrate.

[@evilotis01]

as the other commenter said, it's because polygonal modeling isn't CAD, nor vice versa. if you need precise CAD-style 3d tools and you don't want to/can't just pony up for AutoCAD-in which, case i certainly wouldn't blame you, bc it costs a fortune-you could try something like Plasticity.

@@evilotis01I'm sorry, that's a totally false distinction, however common it appears to be. The reason Blender is so lacking in mechanical design orientated precision is because it was never a development priority. It been playing about with this application for about 25 years. It's always aimed at animated cartoons, filmic visualisation, entertainment and games. It's absolutely nothing to do with the basic geometry engine ie. Polygonal vs, Nurbs vs Brep etc. It's that the developers just didn't know, understand or care much about real world use cases like mechanical design.

[@evilotis01]

um... ok, if you say so

[@Arjjacks]

And that's a distinction without a difference. In Blender it is equally nightmarish to do your taxes in, write essays with, or craft emails in it because those were also never developmental priorities. CAD meshes and polygonal meshes are two completely different geometry types and require two completely different drawing engines to work with. Evilotis is right, you want CAD level precision, you get yourself CAD level tools. People seem to forget that Blender is first and foremost exactly what you just described: an animation program for cartoons, films, entertainment, and game development. Just because you want it to also handle precise mechanical engineering tasks doesn't mean it should or ever will.