When you're done splitting remember to delete all the vertices that are left after deleting the horizontal lines intersecting the spiral cutting. Go to vertex mode, select the whole mesh and hit "del" on your keyboard.
Now it's time to extrude some tracks. Select every other row of faces and extrude them. It's important that when you hit extrude you use the manipulator tool to move and scale the extrude and do not hit "w" or "r" to scale it globally. Because you want to extrude locally, you use the manipulator tools that appear when you click "extrude". Use the z-axis to move and the y-axis to scale. Extrude and move several times to get a sharp edge.
You're done! I think the nut is a bit thick following this reference so I scaled it a bit. Originally I was going to end this tutorial now, but I just couldn't help myself... When you have modeled a nut, you have to model the bolt too... OK, let's go ( bonus feature, wee ) I had to dig up the reference for the whole thing now, so here it is.
Duplicate the nut and move it 8 units in the x axis.
8 - The head of the bolt will look very similar to the nut we've just created. The top will be exactly like the nut's,but the side where we want to extrude the bolt itself is flattening out. First you delete the inside ( where the tracks are ) and then you select the edgeloop that's just standing there wondering what it's suppsed to do. Now extrude this loop inwards and merge all the vertices that meet in the center.
On the other side of the head you're left with a big hole. We have to flatten this side so we get something like the reference image above.
Click for larger image
Delete the loops you see above-left and do not forget to delete the remaining vertices. Then you scale all the loops together so we can get it flat like we so badly want. I urge you to do one loop at the time so you don't overlap etc. When you have all loops perfectly aligned ( you can select all the vertices and grid-snap them in the z-axis. Then you move them back to where they are supposed to be.
Leave the loop to the left on the image below and scale the loop to the right in so we get sharp edges here.
You can do an edgeRingSplit or two and drag the loops to the top and bottom of the head to get even nicer looking edges. Now we're going to focus on the thread for a while. In Maya 7 they were nice
enough to include a new primitive
called helix.
NOTE: When I started writing this tutorial I didn't know that I was going to model the bolt as well so I didn't take that into consideration when I decided how many tracks I needed inside the nut. As you can see on your own model, we only have three, but if I were to do it again I would have created twice as many. You'll see why in a bit.
Create a pHelix and rotate it 90 degrees in the x-axis. Leave the pivot alone. We want it to be where it is. We want to create one coil and duplicate it how many times we need to complete the bolt. These are the inputs I had to insert to get it to fit in the tracks I created earlier. I also had to move it a bit to get it to fit, but I'll move it to tZ = 0 after I nail the size.
Hide the nut so you're left with the helix. Now I want to create the pattern of the typical American bolt out there so I have to do some manual tweeking to the helix. This is the pattern I'm creating.
We don't need the two inner edgerings so delete all those faces and delete the two ending faces.
Select the edgeloop representing the back of our helix ( just look at it as if it was asnake :) ) and bevel it. Edit Polygons Bevel.
The bevel willl make the height go too much down so we need to select that edgering
and scale it a bit to raise it. Because you don't want to raise it in all axis, just x and z,
you hold ctrl and drag the y-axis when you're scaling. This way Maya excludes this axis and scales the
other two.
Use Maya's split edge ring tool to create two loops to sharpen the top of the thread.
Select the outer edgeloop and extrude it once just a little bit and then almost all the way over to the next
ending of the helix aaaaand then the final tiny bit to hit the mesh. Merge the vertices where you
intersect. See the image below for an overwiev
This will be the base we can copy several times to get the whole bolt. Duplicate it once and move it 1.52 in the z-axis. You'll see that the duplicate lands exactly where the other stops.... Why is that? Because the height of the helix is 1.52.
After merging all the overlapping vertices you see why I went "Ohhh, maaan!" when I realized I had to few
tracks. The distance between the threads look stupid.
Bevel.
