Graphics Programs Reference
In-Depth Information
Creating Spiral Forms
You can use the Sweep tool in conjunction with the Helix tool to create a spiral form, such as a
spring or the threads of a screw. You've already seen how the Sweep tool works. Try the follow-
ing to learn how the Helix tool works firsthand.
In this exercise, you'll draw a helicoil thread insert. This is a device used to repair stripped
threads; it's basically a coiled steel strip that forms internal and external threads. Here are the steps:
1. Open the Helicoil.dwg file. This is a standard AutoCAD drawing containing a closed
polyline in a stretched octagon shape.
This is the cross section of the helicoil thread, and you'll use it as an object to sweep after
you've created a helix.
2. Click the Helix tool from the Open Shapes tool group of the Tool Sets palette. You can
also choose Draw Helix on the menu bar or type HELIX ↵.
You see the following prompt:
Number of turns = 3.0000 Twist=CCW
Specify center point of base:
3. Pick a point roughly in the center of the view. A rubber-banding line appears along with
a circle.
4. At the Specify base radius or [Diameter] <1.0000>: prompt, enter 0.375 ↵.
5. At the Specify top radius or [Diameter] <0.3750>: prompt, press ↵ to accept the
default, which is the same as the value you entered in step 4.
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