Tutorials

Lathing (Part 2 of 3)



Index

1. Introduction
2. What we will be making
3. The template
4. Arches
5. It's vertex time!
6. In case of invalid
7. Back to the vertices
8. Variation
9. Goodbye

1. Introduction

Welcome to the second part of the lathing in Hammer tutorial series! Last time we made a spindle, now we are going to take it a step further: it's time to make a vase like object. Remember before when I said that lot's of things can go wrong? We'll some errors are sure to crop up here. This is really not very difficult to do, but it is really messy, and that's the only real problem: sorting out everything on the screen. It's not that hard, and is basically the same as the spindle, it's just alot more tedious and time consuming. If you haven't read the first part of this tutorial, you can find it here. Ready, get set. start your Hammer's!

2. What we will be making

We will make, for all intents, a vase. What you will end up with is an open tube of varying diameter.

But that's not the only application of this technique.

One thing to remember is that lathing is not the only way to make some of these things, but it is the "cleanest." You will end up with, for lack of a better phrase, geometrically perfect objects. Doing things this way will make it ten times easier to link to other geometries while maintaining a clean, seamless, structure.

3. The template

I'm going to assume you read part 1 of this tutorial already, so I'm not going to explain the concept behind what we are doing. Here is the template I'm using

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Set up something similar. One thing to note is that the duplicate on the right side won't be used, after the next step. It is only there to help get an idea of the final shape, and the location of the axis line.

Before we go any further, go to Tools>Options>2D Views tab and make sure that "Arrow Keys nudge selected object/vertex" is checked. This is very important because dragging the vertices will usually screw them up.

4. Arches

To make an open ended structure, like a vase, we will be doing basically the same thing before. Except this time, we will use arches instead of cylinders, and there will be a few extra steps. Also, the axis line will not but up against the template..

So make an arch, doesn't matter how many sides, but make the wall width equal to the width of the bottom of the first template segment. DO NOT MAKE YOUR ARCH LESS THEN 360 DEGREES. Now, duplicate the arch up and up, changing the height of each one to match the weight of each segment.

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Make sure that the interface between each arch is on a line with the topmost vertex of it's corresponding segmet, whether it is the inside or outside vertex. See bits circled in blue.

Now you can either delete one of the template's or keep it. Doesn't really matter either way.

5. It's vertex time!

Ok, so first things first, your going to want to write down the length from the axis line to the left (or right) edge of the arches before you do anything else. So, half the width of each arch for me = 192.
Now, measure the distance from the axis line to the outermost vertex of the second segment on the template. For me it's 207. So, 207/192 = 1.078125, so, I'm going to select the ring of vertices at the interface between the second and third arches, press Alt+E to bring up the vertex scale dialog, and put in 1.078125.

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Now, I need to select the outermost ring of vertices. I'll do that in the top view by holding Ctrl while dragging selection boxes around each one. This will ensure that I get the vertices from both arches.
Then, I will use the arrow keys to nedge the rings down to the corresponding vertex on the template.

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Now, go to the ring of vertices that is at the level which you just dragged from and select one of them to find the corresponding ring in the top view. This is how you identify a ring you want to manipulate when your 2D views get messy.

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Now, to keep things simple, I'm going to move each of those vertices back onto their original spot's, on top of the central ring. You may be wondering why not simply measure their current location, well, they are off the grid so that is impossible. Once they are all back on I'll measure the distance from the axis line to the vertex I want them to be at. Mine is 147. Now, measure the inside radius of the arch. Mine is 128.

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So, once again, 147/128 = 1.1484375

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Now is a good time to hit Alt+P and check for invalid problems. It is almost gauranteed that at some point during the construction of something like this you will find a few, so I'll describe the best way to deal with them now.

6. In case of invalid

Really, we shouldn't get any invalid's during this process, but we all know how finicky Hammer can be, and so sometimes one crops up. Thankfully, they usually show up in a single quadrant or half. Sometimes you will get errors throughout multiple quadrants, however, rarely will all four corresponding pieces be invalid. So let's pretend for a moment that the selected brushes are invalid. In my experience, something like this is your most likely scenario.

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As you can see, the corresponding blocks in other quadrants aren't invalid. So, first we will delete the ones that are invalid. Then we can select the corresponding blocks from the opposite side, duplicate them, and press Ctrl+I to flip them vertically.

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Then we just move them in place to fill the holes. BUT, do not drag them or they are likely to go off grid. Nudge them in place using the arrow keys.

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Then just group each duplicated piece with the arch that it is now a part of and SAVE.

7. Back to the vertices

Let's go over "pushing out" a ring one more time, and look at something else that's interesting. Remember your "base" measurements. These are the measurements from your axis line to the inside edge of the ring and the outside edge of the ring. Mine are 128 and 192, respectively. Select the next interface up.

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Now measure to the outermost vertex of your next template piece. My measurement is 248.

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Once again, we will devide this measurement, the measurement of the desired radius of the outer ring of the interface, by it's current radius (248/192). I get 1.2916666666666666666666666666667. Stop for a moment to consider this number, and what we are trying to accomplish here. The whole reason why we are going through this much trouble to build this shape is because we want it perfect. We want it to look right without any gaps, without any lighting problems, to simplify texturing as much as possible, and because we are anal about geometry <!-- s;) --><img src="https://www.interlopers.net/forum/images/smilies/icon_wink.gif" alt=";)" title="Wink" /><!-- s;) -->. But 1.2916666666666666666666666666667 is NOT precise. Remember 1st grade math? The 6 is repeating infinitely, but computers don't like that so they round the decimal at a certain point, putting a 7 there. Now, we could put this number into the vertex scale dialog, but I want a precise measurement. So, I'm going to try 249/192. It won't match the template perfectly, but that's ok because the template is arbitrary. What is important is that the overall shape is created, perfectly, and most importantly, on the grid. 249/192 = 1.296875 so I'll go with that.

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Look at the above picture. Remember earlier we talked about "finding" a particular ring of vertices to manipulate it indepentantly of other vertices in the same plane? If we simply pay attention to what we see here, we don't have to go through that extra step. Still, it requires using your memory, so the earlier method is probably easier for alot of people. Now I will nudge the rings down to where we want the outer one (on the same plane as the correspongind vertices of the template) and select the ring of white vertices (remember yellow is for edge midpoints) third from the outside and move them back up to their original level.

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1. Now, go back and measure the distance from the axis line to the outer vertex of this ring. I get 166.
2. Divide thet original inside radius (mine is 128), and scale the interface by that amount (so, for me, 128/166 = 0.77108433734939759036144578313253).
3. Then, measure the distance from the axis line to where you want that ring to be, for me it's 203.
4. Divide that number by your inside radius (for me, 203/128 = 1.5859375) and scale by the result.

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Now, instead of doing steps 1 and 2, you could have moved each individual vertex in the ring back to their original positions by simply dragging it ontop of the inner ring. This is what I did before, I'm just showing here that many of these steps can be approached in different ways.

You should have this process pretty well ingrained in your mind by now, so keep doing it all the way up. On my template, I have two spots that are slightly different from what I've been showing you. In one, area, the template segment does not slant but is straight, and above that, the template curves inward. I'll now briefly touch on how I approach those differently.

8. Variation

For the straight sections, simply delete your corresponing arch and make a new one whose bounding box is the width and length of the axis line to far edge measurement, and whoose wall width is the width of the straight section on the template, and move the vertices on the inside to join with the other sections.

For areas that curve inwards, simply reverse your division. Before we divided the measurement from the axis line to where we want the vertices by the measurement of from the axis line to where the vertices are. If we call that A/B = scale#, then to make them slope inwards do B/A = scale#

9. Goodbye

As you can see its a simple but time consuming process. Good luck, and get ready for part three, where I'll show you how to prepare your template for making a dome and how to cap the dome seamlessly.

Mr. Happy

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