Tutorials
Lathing (Part 1 of 3)
Lathing in Hammer part 1
Index
1. Introduction
2. What we will be making
3. The technique
4. The template
5. Pressing on
6. It's vertex time!
7. Moving forward
8. A final word
1. Introduction
In woodworking it's called lathing. In XSI, you just click "revolution around axis" in 3DSMax...well, I'm sure it's easy there too. In Hammer though, it's known as painfully tedious and boring. So get ready for some late nights of vertex manipulation bucko, we're in for a long ride.
2. What we will be making
This will be a series of three tutorials. We'll start off easy, with two solid spindles. In the second tutorial we will make hollow spindle, and in the third a bowl. That's where it get's really interesting, as using this technique you can make geometrically perfect domes. Below you can see the finished spindles.
3. The technique
We will be using a somewhat hidden feature of Hammer, the vertex scaling dialog. With this powerfull but little known tool you can make all sorts of cool things. I'll also show what will go wrong, and how to fix it. Since this process is fairly complex and highly variable in your success rate (sometimes Hammer just doesn't wanna play) I'll get this out of the way: if somethings screwed up, I probably can't help you. BUT, if you have a decent knowledge of Hammer and a good understanding of 3D space, you shouldn't have any problems. Am I exagerating the difficulty? Yes, absoultely. Especially for this first tutorial. Pretty much all your problems will crop up in the second and third tutorials, and we will tackle them there.
4. The template
The first thing you need is a template. Sometimes called a key, it is a profile of half of the finished object. Get the block tool out and make a spindilish shape, but make sure that all inside faces touch the axis line. Look at the picture for this to make sense: Also note that this step takes place in either the side (x/z) or front (y/z) views. Personnally, I don't use the front view. Ever.
Two more things to note here, using dev_measuregeneric01 makes the template alot easier to see later. Also, each "step" is in increments of two. I'm doing this one pretty large so that's 128, 256, 384, and 512 units. This is not neccessary, but is alot easier to work with. At the end will be a small section on doing it with a "random" grid."
5. Pressing on
Now we are going to make a series of stacked cylinders. Make a cylinder, with any number of sides that dont create a "wrong cylinder" that has twice the radius of the width of the bottom segment. Line up the central axis of the cylinder with the axis line and one side of the template, as shown below. Use dev_measuregeneric02.
Now duplicate the cylinder as many times as the number of sections you have, and scale each one's height to match the height of the section on the template. For the purposes of this tutorial, the template is made of blocks that each have the same height. Once again this is not neccessary, and doesn't effect the process in any way. Just make each cylinder is the same height as each template section.
6. It's vertex time!
Ok, select the second and third cylinders from the bottom and press Shift+V to use the vertex tool/morph mode. Now, draw out a selection box encompassing the vertices in the middle. As shown below.
OK, because we made our template segment steps in multiples of two, this is going to be alot easier than normal. You see the cylinders are 1024 units wide and the template comes in 256 units at this interface. So we know that we want the diameter at this interface to be 25% less than it is. That means the radius needs to be 50% of what it currently is. Of course, in decimals, 50% is 0.5. Press Alt+E to bring up the vertex scale dialog. What this nifty little contraption does is, basically, scale the bounding box that defines the placement of the selected vertices. I know, a rectangular prism doesn't have a radius, but for our purposes, it does. So type in .5 and the selected vertices will snap into places consistent with the template.
Hit enter to close the dialog, then select the next cylinder (and deselect the bottom one if you want). You can select the cylinders while the scale dialog is still open, but it's good habit not to as you can really screw things up accidentally with more complex structures. So, select the next ring of vertices and hit Alt+E again. Here my radius of the template is 384 units, or, 75% of the 512 unit radius of the cylinders. So type in 0.75, hit enter, and wonder at the marvels of vertex scaling.
I'm sure I don't need to tell you what to do next, but then again, the tutorial wouldn't be complete if I didn't! So, select the top cylinder and then the top ring of vertices. Hit Alt+E again. Here, I have made the diameter of the template wider than that of the cylinders. The cylinders radius is/was 256, while the top ring is 320 320-256 = 64, or, 25% more. So type in 1.25 and be done with it!
Now just delete your template brushes and make love to your new spindle! Obviously, you can do this with any number of segments in your template, which can all be different heights as well.
7. Moving Forward
What is slightly more difficult is if you want to make a segment with a radius that is not anywhere near as proportionaly nice as in this tutorial, so let's go through doing that real quick. Basically, there are two ways of getting an odd radius to match your template. Until tonight, when I gave it some thought, I used the first, sloppier, way, which involved trying smaller and larger numbers until all the pixels on my monitor lines up. That was tedius, and there's a better way. Basically, just what we did before. But for those who aren't math-inclined I'll describe in detail.
Below we have a another template. As I write this sentence, I don't know the width/diameter of the interfaces that I moved, I just nudged them around. But, the bottom, middle, and top edges/rings are 1024 wide so I'm going to make my cylinder stack 2048 in diameter.
1. Ok, let's look at the second and third ones from the bottom, the interface/rings here is indented.
2. Deselect everything and draw out a bounding box from the middle to the indent. Mine is 604 units long, write down yours.
3. Select that two rings of vertices at that interface. Hit Start+R, type calc, and hit enter to bring up the windows calculator. Do the width of your bounding box divided by the radius of your cyliner, so, for me, that's 1024/604 = 0.58984375
4. In the calculator hit Ctrl+C to copy the result and then Ctrl+V in the vertex scale dialog to paste it in. Don't approximate. The vertex scale dialog works with infinite precision!
5. Do the same for the other next one. In my case, the interface is wider then the cylinder. The bounding box being 1306 and my radius 1024, the number I ended up with is larger than 1. Tt's 1.275390625 actually.
Delete your template and we're done!
8. A final word
Well, that was easy, right? Don't worry, I promise it will get a lot more tedius in parts two and three, but, until then, have fun!
-Mr. Happy