Small CAD Drawing Opens Slowly as a Workaround Solution

Why Small CAD Drawings Sometimes Open Slowly

When I receive a CAD drawing, it often takes a long time to open, and sometimes the program even crashes. The issue usually comes from the hatch patterns used in the drawing. For example, the filled area circled in red in the image below is supposed to be filled with a SOLID pattern. Instead, it’s filled with an ANSI37 pattern set to a column spacing of 0.010. If you try to explode these hatch patterns, it can generate hundreds of thousands of individual lines.

Solution:

There is a variable in CAD called HPMAXLINES that controls the maximum number of individual hatch lines displayed. If the number of hatch lines exceeds this limit, the hatch will be displayed as a solid fill instead. By default, HPMAXLINES is set to 1,000,000.

When dealing with drawings that are small but open slowly or cause memory overflow, try lowering this value before opening the file. For example, enter the command HPMAXLINES, press Enter, and set the value to 300,000. Then open the problematic drawing. Since the hatch in the fire hydrant exceeds 300,000 lines, it will be displayed as a solid fill, allowing the drawing to open, zoom, and operate smoothly.

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