How to make a precise bolt hole in a simpler way? I'm new to blender and using it to create 3d objects for my printer.
Part of this is "cutting" holes for bolts very precisely which I managed to do but my way is so long/tedious I must be missing something.

Here are my steps which I am illustrating with an imaginary use case I created for proper step-by-step exposure of my method.

My bold head is 0.8m radius (1.6m diameter) and 0.5m height.The thread of the bold is 0.6 radius (1.2m diameter) and infinite lenght. I'm cutting this hole in the center of the "top" face of the default 2m cube.

So here are my steps:


I am creating two curve>circle in object mode with respective radius of 0.8 and 0.6 for the bolt head/thread. I precisely position them where I want (here, at the center 0,0)

I then select both circles and the cube, go in edit mode and mesh>knife project (cut through).

I delete the "top" round faces and extrude the bottom Annulus (apparently that's how it's called) 1.5 meter (since 0.5m is my bold head height).

Since I extruded it, the "bottom face" has gone up and it's missing in bottom position.

So I select every edge as shown below and "bride edge loop" them.


Now I need to create the faces for the bolt head housing so I do a similar operation (select every edge as shown below and "bride edge loop" them).


Then I check with the 3D printing extension and I have 96 Non-Manifold edges.

Thanks to What is non-manifold geometry? I realize it's because of internal faces so I tediously delete all the edges constituting the internal faces.

I then get the result below but checking again with the "Check all" 3D printing extension I have 96 bad contig. edges.

But this time the "Make Manifold" auto-resolve is working for me so it's finally good.



At this point, I've spend a lot of time for what I would expect to be a simple task, how would you do it in a faster/simpler way ?
I'd do it almost your way, just skipping a couple of steps..




As you did, knife Project and cut through
Deselect the bottom faces, and E extrude the top faces downard, numerically entering the depth of 0.5 in the 'last operator' panel
Select the top and bottom inner faces, and..
...'Bridge Edge Loops' (you don't need to delete)


However, if your topology is simple enough to stand it, and you wouldn't need to do too much tidying afterwards.. you could just make and duplicate the bolts in the correct dimensions, and cut them all out in a single boolean operation.