Bisect tool at precise angle is this possible?

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Hi guy’s, learning my way from autodesk to blender and is there a way to bisect with precise angle like 45 degrees for an example?

By the way this tool so far crash blender to desktop when manipulating the gizmo and i am on latest stable build 2.91.

If not please let me know if there is an addon for this.

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Since its introduction that tool in Blender was more of a freeform thing than anything. You could adjust the angle after the fact in the redo panel, but that’s only practical if you’re doing axis-aligned cuts, when the angles are easy to work out.
The alternatives are:

  • Knife tool with cut-through setting (modal key z) and angle snapping (modal key c). That one only allows 45 degree increments though
  • Face -> Intersect (Knife). With that one you can, in edit mode, just add a plane and rotate and position it however you want, then do a cut. It does require some cleanup work afterwards (removing internal face), but at least you can be precise with it.
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Hi Stan, just tried the intersect and i get an error message saying no intersections was found?

OK got it it need 2 mesh sorry my mistake

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I know this is long after the fact, but I figured out how to get a precise bisect. It does require a bit of trigonometry, but with google’s help that doesn’t have to be intimidating. I wanted to do a bisect along a plane at a specific origin point, and needed it to be specifically at 68 degreess around the X axis.

So

  1. First just create the bisect line wherever to bring up the Redo pane
  2. Enter the origin point in the redo panel.
  3. This is the tricky part. Think of the Normals along the axes as the edges of a right triangle (a triangle where one of the angles is 90 degrees).
  4. In my case, since the bisect I was doing was 68 degrees around the X axis, so I set the X normal to 0, and worked with the Y and Z normals. Trigonometry tells me that the 68 degree cut will form the hypotenuse of my triangle.
  5. Knowing the trig formual "TAN (angle) = Length of Opposite triangle edge / Length of Adjacent angle edge, I looked up the TAN (tangent) of 68 degrees, which equals about 2.475.
  6. So in my case that means that if the lenght of the “opposite” edge of my triangle is 2.475, then the length of the “adjacent” edge will be 1.
  7. In my case, the “Opposite” edge was along the Z axis, and the “Adjacent” edge was along the Y axis, so if Z = 2.475 then Y = 1
  8. But Normal values cannot exceed one. So next I had to divide both my Y to Z ivalues by the value of Z (the larger number), so that the value of Z becomes 1, and the value of Y becomes Y/Z and therefore less than one.
  9. So my final Normal values became X = 0, Y = 0.404 (that’s 1/the orignal Z value of about 2.475), Z =1. I had to flip a couple of signs from positive to negative, but otherwise it worked perfectly.

Maybe somebody else with the time to make this into a pretty tutorial can do so, but this should at least get you started. I’lll probably be referencing it myself again in the future. Hope it helps.