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When using the Haochen CAD software for CAD filling, one must first select the filling pattern, and then set the filling scale. For example, either an excessively low or high filling ratio can cause the pattern fill to appear as a SOLID fill. Today, I will introduce to you other related issues and tips regarding the setting of the CAD filling ratio. I. How should the CAD filling ratio be set? The dimensions of drawings created using CAD vary greatly; the dimensions of some mechanical part drawings are just a few millimeters or even less, while those of municipal or topographic maps can be several dozen kilometers. However, the unit size of the filling patterns remains fixed, and as a result these patterns may be either too large or too small for the area they are intended to fill. It is advisable to set a reasonable scale value in advance before performing the filling process. But how should this scale value be determined? Actually, there is a simple method. If we are using CAD-standard hatch patterns, we first need to determine at what scale our drawings will be printed. We can set the hatch scale according to the printing scale; for example, if our drawings are to be printed at a 1:1 scale, there is no need to change the default scale ； If the drawing is to be printed at a reduced scale, for example at 1:100, set it to 100 first; for printing at 1:1500, set it to 1500 in advance ； If the drawing is to be printed at an enlarged scale, such as 10:1, the scale should first be set to 0.1. Using this method, it is possible to ensure that the pattern displays properly during filling, after which we can make adjustments as needed. But if we choose the wrong fill pattern, this method may not be suitable. II. The CAD fill patterns and scales are the same in both drawings, so why do they appear so different? In the two drawings, two areas that appear similar or even identical use the same filling pattern and have the same scale, yet they look very different, as shown in the figure below. In the image above, the rectangles all have the same dimensions, the fill pattern is ANGLE for each of them, and the scale is 1 for all of them as well. Yet there is a significant difference in density – why is that? Many people know that CAD comes with two fill files, but few are aware of the differences between them, let alone which file to use and what settings are related to that. The template files that come with HaoChen CAD are similar in nature; one of these templates is for imperial units, while the other is for metric units. When a template file in imperial units is used, the imperial filling file will be called; when a template file in metric units is used, the metric filling pattern will be used. The dimensions of the fill patterns in imperial units are set in inches, so the size values of the cells are smaller ； The patterns in the metric system are set in millimeters, and the size values of the units are larger; generally, they are obtained by multiplying the sizes of the patterns in the imperial system by 25.4. In other words, on imperial drawings, the size of the filling units must be 25.4 times smaller; this results in a denser appearance when filling areas of the same size. In fact, although the size value of the region is the same, its actual size is 25.4 times larger. The choice between metric and imperial hatch patterns in CAD drawings is actually controlled by a variable, namely MEASUREMENT: when set to 0, imperial units are used, and imperial line styles and hatch files are applied ； When set to 1, it is metric, and metric line and fill files are used. If we realize that the wrong template file was selected while drawing, it’s no problem – simply type MEASUREMENT, press Enter, and change the value. Similar problems can also arise if imperial or metric templates are used incorrectly; let me briefly explain these as well: 1. On the same drawing, it is possible to have patterns with the same scale but different densities. A similar problem occurs when filling is copied and pasted from a metric drawing to an imperial drawing, and vice versa, as shown in the figure below. After this occurs, the pasted fill may have a different proportion from normal fills, but it will retain its original appearance when moved, copied, or saved; therefore, a similar phenomenon can also be observed in drawings created by other people: the same fill pattern appears to have different cell sizes. 2. Double-click on the fill to open the dialog box; by confirming without modifying any parameters, the fill changes. In the example above, when double-clicking on the fill that was copied over and confirming without changing any parameters, it can be seen that the fill changes to the normal cell size, as shown in the figure below. But this situation occurs in CAD versions that default to opening the fill dialog box upon double-clicking, such as version 2007. In higher versions, double-clicking on the fill pattern does not bring up a fill dialog box, and the fill pattern does not change immediately; however, if another pattern is selected or the original CAD fill pattern is used again, the fill scale will change. 3. Use the CAD pattern brush to apply filling, only to find that the filling ratio is different from that of the original graphic, or nothing changes at all after applying the brush. For example, if we use the copied fill as the source object to apply it to other fills in the image, we will find that the proportion of the fill applied is not the same as that of the source object, as shown in the figure below. The above are the issues related to the filling scale that may arise when using the HaoChen CAD software for CAD filling. If you encounter such problems while drawing, you can refer to this CAD tutorial for guidance.