Knife Project Tool
The tool you are looking for is the Knife Project tool. Here's how to use it:
Create your cube that you want to put the circle on
Add a circle curve: SHIFTA -> Curve -> Circle
Position the circle in front of the face you want to put the circle on, as shown here (highlighted in green):
Now go to the viewport where the circle ...
I would recommend using the bisect tool (new in Blender 2.69):
Enter edit mode (Tab), then press Space and type in Bisect, or select Bisect from the toolshelf (under Add).
Click and drag, to bisect the object.
Press F6 to bring up the options for the tool, and select clear inner, or clear outer depending on which half you don't want.
If you don't want to ...
Press C while in knife mode to enable Angle Constrain.
Note that it snaps to angles relative to the view. For cuts on faces which are not aligned to any axis, you can:
Press ShiftNumpad 7 to align the view to the face
Press K to enter knife mode, then C to enable Angle Constrain:
In your particular situation, it looks like the bridge tool is what you want. Select two or more edge loops with AltShiftRMB, and then connect them with W>Bridge Edge Loops:
To do exactly what it looks like you are trying to do in your screenshot (connecting two vertices with an edge), select the two vertices and press F to create edge/face.
If you ...
A recommended workflow here would be:
KZC, then drag a perfect vertical line. (Optional for C)
Menu: Select > Select Loop Inner Region, to select one side of the cut result.(F6 > Select Bigger to select the other side)
Assign a second material for the selection. Done.
As shown below:
This is because knife project only uses wire or boundary edges:
Knife projection is a non-interactive tool where you can use objects
to cookie-cut into the mesh rather than hand drawing the line.
This works by using the outlines of other selected objects in
edit-mode to cut into the mesh, resulting geometry inside the cutters
outline will be ...
This is a work around.
For a simple object like your cylinder, simply rotate it in object mode 35°, make the cut, then rotate the object back.
For more complex objects where you can not rotate it. You can align the view to a rotated face. You could duplicate a face out of your mesh and separate it in to a new object, or just add a new object, a plane or an ...
This currently isn't directly possible with the knife tool, but it is possible with a few other tools:
Add a plane and rotate it the desired amount (e.g. R 35°)
Align the view along the axis you want to cut
With both the plane and the target object selected, enter edit mode (↹ Tab) and press knife project in the tool shelf (T)
You can use C while using the Knife Tool to enable Angle Constrain. This will enable you to cut at the following angles (with reference to your current view):
At 45° angles
Also, notice that when you start to use the Knife tool, the 3D View Header bar changes to show you all the available Hotkeys to perform all ...
If you're talking about cutting panels, There's a very nice non-destructive method demonstrated by Penfinity, at the time of writing, in two videos, here and with an improvement thanks to Nahuel Belich, here.
Penfinity likes to be a bit of a magician, so this answer will try to slow the explanation down a bit; draw back the curtain.
1. Select the Edges
Bisect with boundary edges.
Based on the rectangular nature of the corners of given mesh.
Sample result, far from optimized as some edges above could be dissolved.
A script to create a plane from all the boundary edges. The plane coord is edge center, the plane normal is nominated up direction (Z axis) crossed with edge direction.
Script, run in edit mode. ...
Actually, you only need one single circle here instead of two.
First, after using Knife Project, find Cut Through on the lowerleft corner of the Toolshelf bar, or toggle it on the F6 panel.
Second, select each pair, then W -> Bridge Edge Loops, to build faces between them (solidify the holes).
If you want to create two identical halves from a symmetrical mesh, all you need to do is to tab into Edit Mode and press Numpad 5 then Numpad 1. Now you can press B for Box Select and drag over the vertices to one side of the center line, then delete those vertices.
This method can be used to make Vertex Groups for easy selection, so you can assign ...
Use the knife tool or loop cuts to build your mesh, and then here is a trick to move a vertex or edge to a precise position relative to the corner:
select the vertex or edge you want to move
move it all the way to the corner, validate
move it back (for example with GX), enter the distance on the keyboard.
There is not super simple way of doing this like there is in Sketchup. There are a few ways to do this in blender but this is the best way I have found.
Here is how:
Select the face and subdivide it to add more geometry for the circle
Select the edges that will make up the circle
Scale the edges to sphere, Alt Shift S
scale all the way to 1 to make it ...
There is a Cut Through option for Knife Project tool, as shown in Figure 1 below (btw, since Knife Project tool doesn't require the curve being snapped to the surface, the Shrinkwrap modifier isn't quite useful here, just make the projected cut through the ortho view, Top view in your case);
P to separate the default selection after that, see ...
Knife will cut through obscuring faces, if Z is pressed while cutting, either on solid or wireframe mode.
Midpoint snap can be activated by pressing Ctrl while cutting.
Further options are displayed on the 3D View area's header, while Knife tool is active.
If you have a face on the edge perpendicular to the front face, then you can select the face and move the view with ShiftNumPad 1. That will rotate the view so that the edge is alined, then the angle constraint in the knife tool will work.
The point is to have the good amount of vertices so that the two can fit easily.
If the cylinder part exposes from top to bottom 9 vertices (ring of 16) then the torus should have 16 minor segments.
Place the two shapes like so, so that they overlap:
Add a boolean union modifier to the torus using the cylinder as object:
The knife tool has no undo support.
While it is possible to have undo history in a modal operator tool, at this time the knife tool does not. Nor is adding undo functionality planned.
However after confirming the knife tool cut, there are other modeling tools that can help you get around a misplaced vertex.
X > Dissolve Vertices, that will delete the ...
One way to do this is to use Knife Project
In Edit Mode Alt click the edge loop of the smaller tube connecting to the bigger one. Then Shift + d (and Ctrl click) to duplicate it in position. P to separate by selection.
Now in Object mode select the newly made edge loop object, then Shift shift select the bigger tube (in that order).
Go into Edit Mode, line ...
It could be a CtrlShiftB, 1-segment Vertex Bevel:
You can adjust to precision in the operator's F9 Adjust Last Operation panel.
Thanks to @John Eason for the reminder.. While modelling, always have your object's Scale CtrlA applied to (1,1,1) for predictable results from operations and modifiers.
Edit: The shipped add-on 'TinyCAD' can find the projected ...
After invoking the Knife Tool the status info shows:
For each cut:
Press C to align the cuts
Press Z to cut through
First cut the vertical then the horizontal edges.
After removing the faces you would need to add more edges (highlighted vertices) or use the Window creator and place a completed window at this position.
For instance :
Starting from a circle :
Add a circle
In edit mode (Tab) extrude E and stay in place (Esc or RMB)
Select all and extrude again E
Or from a cylinder :
Remove top and bottom the faces
Then same principles as above
Or using curves :
Add a plane
Keep only the edges X the 'only faces'
Back to object mode convert it to a curve ...
Try to start with more simplified geometry connected without n-gons.
Start with 10 sided Circle and continue extrude, scale, as needed)
Use Subdivision Surface modifier to round curved parts
and Edge Crease Shift+E 1 to keep corners sharp.
Similar to this.
Note: I probably used too low topology, when I would like to bevel edges now, I would have to add ...
Yes your initial array method will work. Here is the model of a circle. I have extruded it into a cylinder and delete the faces I don't need and apply an array modifier to get the below mesh. I have intentionally left out the last array object. With the mid-edge of the original mesh selected ...
Hit CtrlB to bevel the edge and you should achieve this...
I've used a topology similar to yours and it seems to work fine with almost no artifacts. I just used and applied a Shrinkwrap modifier with a cylinder of the same radius as Target in order to correct the topology a bit and make it stick to a nice cylinder shape:
You could do the other way around, beginning with the shape then extrude to get your rectangular object, at the end when you'll give it the Subdivision Surface modifier it will just need a bit of work to get the sharp angles:
In addition to learning Blender's native boolean operations, I highly recommend you check out a free add-on called BoolTool (version 0.2)
Here is the link to the add-on.
Here are my notes for using the BoolTool add-on.
It makes booleans so easy that you can use Blender like ShadowBox in ZBrush.
Q: How do I use the BoolTool Add-On?
Create a cube.