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In the process of drawing CAD drawings using Haochen CAD drawing software, it is generally necessary to set the CAD proportion. Today, I will explain the setting of CAD proportion parameters in detail from three aspects. CAD drawing scale us * Commonly referred to as CAD 1: 1 drawing, this 1: 1 should be regarded as the concept of proportion, but in fact there is nothing in CAD 1: n drawing argument. Let’s not say that inputting 100 is 100mm. Strictly speaking, what we input is 100 graphics units, because we are using the metric system, and 1 graphics unit in the metric system is 1mm in CAD. Drawing is based on the set graphics units and the actual drawing. For a line with a length of 1m, you enter 1000, not because the drawing scale is 1: For 100, enter 1000/100=10. In this way, CAD software drawing actually does not have the concept of drawing scale. Real objects have no proportions, only non-physical objects have proportions. Since CAD can draw the object as big as it is, then the actual object has no proportions. However, non-physical drawing information, such as text, dimensions, and symbolic graphics. Originally there was no such thing as proportion, but there is proportion in CAD. Why? Because when electronic files are printed into physical drawings, 1 is used.: n Zoom printing, all objects on the picture must be scaled equally. In this way, 5mm high text on the physical drawing, when the printing scale is 1: When 100, the CAD electronic file must be set to 500mm so that 500/100=5. In other words, during the drawing process, non-physical content must consider the drawing scale. The proportional dimensioning global scale factor in the dimensioning style is the system variable DIMSCALE. The measurement unit scale factor is the system variable DIMLFAC. The fractional height scale factor is the system variable DIMTFAC. Let’s talk about the measurement unit scale factor first, DIMLFAC=1, which is the default setting value. If we call the size values shown on the diagram dimensioning values, then: Dimension value = actual measurement value × measurement unit scale factor. Through the above formula, we know very clearly that if we want to draw pictures of different scales on a picture and do not use paper space, we have to artificially scale certain graphics, such as in 1: On the main scale diagram of 100, draw 1: 25, we need to enlarge this part of the figure 4 times. The length of 1000 becomes 4000, and the dimension is also 4000. However, we do not want to mark it as 4000, but still want it to be marked as 1000. In other words, the actual measurement value = 4000 and the dimension value = 1000. Obviously, the measurement unit scale factor DIMLFAC = 1/4 = 0.25 at this time. By the way, I think it is not advisable to use the method of inputting data or editing the data after breaking it without using this system variable. The above are three methods for setting CAD proportion parameters in Haochen CAD drawing software. Mastering these methods for setting CAD proportion parameters will be of great help to our CAD drawings!