SolidWorks 2011 Parts Bible - Matt Lombard [93]
Estimating sharp edges
When you are drawing a sketch of an object, you are usually drawing theoretically sharp corners of the model. Real parts usually have rounded corners, so you may have to use your imagination to project where the 3D surfaces would intersect at an edge minus the fillets.
When you are reverse-modeling a part from images, you are not using an exact science. It is better than not being able to put pictures into the sketch, but there is nothing about it that can be considered precise.
Using Auto Trace
Auto Trace is an add-in that you can select by choosing the Tools⇒Add-ins menu. Auto Trace is intended to trace between areas of contrast in sketch pictures, creating sketch entities. To use Auto Trace, make sure the add-in is activated. Activating the Auto Trace add-in activates a set of arrows at the top of the Sketch Picture PropertyManager. There is nothing to identify the functionality with the Auto Trace name. Figure 6.11 shows the Sketch Picture and Auto Trace PropertyManagers. The sliders for the Auto Trace functionality do not point out which end is high and which is low.
FIGURE 6.11
The Sketch Picture and Auto Trace PropertyManagers
Auto Trace works best with solid blocks of black and white in the Sketch Pictures. To achieve this, you may need to use image processing software and reduce your picture to a two-color (black and white) bitmap, TIF, or PNG image. Even if this pre-processing gives perfect results, don't expect much from Auto Trace.
I can't imagine a situation in which I would use this myself or recommend anyone else use it. In all cases, including idealized demonstration images or those in which traced images would be of the most benefit to the user, such as logos with complex curvature, I believe it would be faster and more accurate to do the tracing manually, even it means using splines.
Using Sketch Text
Sketch text uses TrueType fonts to create text inside a SolidWorks sketch. This means that any TrueType font that you have can be converted to text in solid geometry; this includes Wingdings and symbol fonts. Keep in mind that some characters in certain fonts do not convert cleanly into SolidWorks sketches. Sketch text still has to follow the rules for sketching and creating features such as closed contours, as well as not mixing open and closed contours.
You can make sketch text follow a sketch curve; to space it evenly along the curve, you can control character width and spacing, as well as overall size, by specifying points or actual dimensions. Sketch text can also be justified right, left, centered, and evenly, as well as reversed, rotated, and flipped upside down. Figure 6.12 shows the Sketch Text PropertyManager and some examples of sketch text options.
FIGURE 6.12
Examples of sketch text
The icons in the Sketch Text PropertyManager are self-explanatory, other than the Rotated Text option, which rotates individual letters (as shown in the Dimension the Placement Point text in Figure 6.12), and not the whole string of text.
You can use the Sketch Text tool multiple times in a single sketch to make pieces of text with different properties. Each string of text has a placement point located at the lower left of the text. This point can be given sketch relations or dimensions to locate the text.
If the text overlaps in places, as shown in Figure 6.12, you can correct this in a couple of ways. First, you can extrude it with the Merge option unselected so that each letter is created as a separate solid body. You can also explode sketch text so that it becomes simply lines and arcs in a sketch, which you can edit the same as any other sketch. You can also adjust the Width Factor and Spacing settings.
Starting in the 2010 version of SolidWorks, you can link the text to a custom property. This means that sketch text can be changed