Hello everyone,

an example to support this idea (example DWG file is attached):

I have a simple DWG file with two lines (blue), one text (yellow), a dimension (magenta), and a polygon (blue) which is filled with a hatch (cyan): 

If I now simply read the DWG file with a REALDWG reader and do nothing but write it again with the REALDWG writer, 

the hatching pattern looks very different in the result - which is basically because the lines of the hatching pattern are much closer together than they were in the original DWG file:

Comparing the output to the original in AutoCAD, the scale values look correct, but the hatch scale appears to be wrong visually. It is strongly suspected that this may be tied to the fact that FME does not support associative hatches yet.

See AutoCAD DWG - Preserve pattern style of hatches (safe.com) for additional information.