Talk:Blender 3D: Noob to Pro/Pipe joints

Number of vertices for a cylinder
In figure 1 the top left cylinder has 16 vertices at it's top and 16 vertices at it's bottom. The number of vertices is what you fill in in the dialog "Add Cylinder". --SoylentGreen (talk) 17:10, 16 March 2009 (UTC)

6 cylinder joint
Confusing: The second pipe joint: The instruction to select middle vertices in the edges is ambiguous, no specifications as to what vertices and which edges.
 * All vertices in the middle of an edge (12 vertices in total), but not the vertices in the middle of the faces. --SoylentGreen (talk) 06:45, 11 August 2009 (UTC)


 * I've updated the photos, it should be crystal clear now Pearts (talk) 22:58, 11 August 2010 (UTC)

Math question: Why does scaling by a factor of 1.4142 work in this case? I understand how it works for the T-Joint, but can someone explain the math for this example?

The math for this is fairly simple. When given a triangle with two 45 degree angles (called a 45-45-90 triangle), using the Pythagorean Theorem you can determine that if the two sides on the 90 degree angle are given the length of one, the hypotenuse (other side) has a length of square root of 2. Here's a picture that may help: http://commons.wikimedia.org/wiki/File:45-45-triangle.svg

Scaling along axes (T joint)
I removed some notes:
 * Scale with constraint Y axis (S->Shift-Y), about 1.4124 (square root of 2)
 * (Blender Noob: In 2.47 this should be Y instead of shift+Y, I think this is the same in all recent versions and the tutorial is wrong.)
 * The tutorial is right (of course ;-)). Shift-Y scales at the X and Z axes while keeping the Y axis. This is what we need here.

Following the tutorial it works exactly as described. The vertices are extruded along the X axis. I have added a bit about the view. It may be misleading that figure 1 shows the model rotated 90° clockwise. --SoylentGreen (talk) 14:49, 20 March 2009 (UTC)
 * To flatten the front: scale at the X axis by factor 0. (S-X, 0).
 * (Blender Noob again: Using the factory default for 2.47 this should be Y.)
 * I've rotated figure 1 so that is meets the 3D view. --SoylentGreen (talk) 15:03, 20 March 2009 (UTC)
 * The (S->Shift-Y) is Wrong:

It means scale the vertices in two dimension : X&Z. but it doesn't really scale it in Z. i think (S->YKEY) is true.Worm 19 (talk) 13:04, 1 August 2010 (UTC)

I wondered about this myself, I will make the nesscary changes in the description of axis's being moved Pearts (talk) 01:34, 11 August 2010 (UTC)

Using shear
Wouldn't a shear (^S 1) be simpler than this scale/rotation combination. The only drawback I can see is that it is view-dependent. 63.224.110.152 (talk) 23:17, 28 June 2009 (UTC)
 * I agree. Though I can also ad to your comment that pressing the middle mouse button will let you cycle through the different option of where you would want to shear of, making the use of the pythagoram theory unnecesary. May this method be added as an "alternative method"? Mswf (talk) 17:18, 9 April 2010 (UTC)

6 cylinder joint - easier but not equivalent
Vaakmeisster has suggested following method: A faster way to make a 6 pipe junction is: This method is simpler, but doesn't lead to the same result, the insertion will be thicker than the pipes.
 * Add a cube.
 * Go to edit mode.
 * Select all six faces of the cube with key A if they are not selected already.
 * Extrude individual faces by 2 grid units ( Press E in your keyboard -> Individual Faces then type 2 with your keyboard).
 * Now select the outer faces of the block and delete to create the holes. You should delete 6 faces in total.
 * Now select everything, click set smooth and subsurf and you'll get a 6-pipe junction. You also could crease some edges to clean up the mesh ( do this by selecting the edge and pressing shift E).

Another Way
This seemed quite complicated, so all i did was to delete the right faces from the default cube, extrude the edges, subsurf and then crease the joints. The result was almost the same.

Flattening the tee
User Comment: To flatten the front I had to relocate the 3D-Cursor to the vertices where the V-cut comes together, then select only the top half of the vertices and scale in the Y-axis by factor of zero. Then select the bottom vertices and do the same. Everything else in the tutorial worked perfectly.


 * You need to set the centerpoint thingy back to median, in order for it to work the way it was written, i've bolded it Pearts (talk) 01:32, 11 August 2010 (UTC)

Normals
A thought has just occurred to me... Part of the Jeep Body tutorial detailed how the wrong normals would make part of the model invisible, since the render would ignore the 'inner' surface. My question is... how can we see a render of the inside of the pipes when the normals are shown only on the outside?

Kevintropman (talk) 15:31, 10 November 2010 (UTC)

Question about T joint
I this section there is one part saying: "There will be 6 vertex overlapped: 3 vertex linked to the top of the tube, 3 vertex linked to the bottom of the tube Select 3 of this vertex Depending on which half the vertexs are now selected you will need to rotate by -45 or +45."

Actually there a 14 vertex overlaped, 7 on each side. Also after pressing V there are 7 vertex selected.

The almost last step is to change Pivot to Median Point, but Median Point and 3D Curser are the same? Why should one do that?Adam.Elenktik (discuss • contribs) 16:10, 2 June 2013 (UTC)

Proportional Editing?
Okay, when this is done

tap on "Proportional editing" and set it to "connected" and select Falloff Type "inverse square"

after ripping the mesh, the seven new vertices just created disappear, and I only have one set of seven in the middle, not seven overlapping vertex pairs. --Egdcltd (discuss • contribs) 19:40, 5 October 2016 (UTC)

Snap During Transform?
In my version of Blender there are a couple more buttons that have to be selected before this will work. Following the instructions here left me very confused.

I had to select Snap-During-Transform, Faces, and Closest as described. But then I also had to turn OFF Snap to Self, turn ON Align Rotation with Snapping Target (a hint from some other discussion elsewhere), and also Project Individual Elements on Surface of Other Objects.

Unfortunately I am still confused, because while my "circle" (octagon) seems to be projected onto the faceted surface of the crude cylinder and I used ctrl-J to Join them, the edges which make up the circle do not in fact intersect with the edges of the cylinder! i.e. where the edges cross, they don't actually intersect. If I select for example the inside of the circle, the whole cylinder face is selected, not just a pie-shaped piece of it. It is as if the circle was "floating" on the cylinder surface, just above or below the actual cylinder mesh. They have not merged.

I therefore cannot "delete the center vertex" because if I do, a big chunk of the cylinder vanishes. I am kind of stuck here and not sure how to proceed; Snap During Transform seems to be a tricky feature (I note lots of questions being asked about it online) so I will try practising it with other meshes and see if I can get it to work someday.

update: after much headbanging I discovered that at some point the cylinder had been duplicated (???) and the face I was wrestling with was on the duplicate cylinder. after removing it, the cutout worked properly and I could make the tee/adapter with 2 sizes of pipe.

I notice that when rendering my 6-way pipe joints there is a lot of noise (Blender Render), and the received wisdom is that this noise derives from "Z fighting" and is a symptom of overlapping surfaces. When I looked closely at my 6-ways I found that indeed, they were "doubled" strangely -- normals are displayed on both inside and outside, and I can delete selected faces from inside or outside and still have what looks like a complete structure. I have no idea how this happened or how to fix it -- have tried every Clean Up option in the menu and nothing seems to solve the "two sided faces" problem. If anyone knows how this happened or how to get rid of the "inside faces", I'd be grateful for some advice.

Tazling (discuss • contribs) 05:58, 20 November 2016 (UTC)