I don't see what changes I can make to get a 24hr clock in SH3D.

You system must be in English, and Java doesn't see you're actually in Danemark. You should force your country by setting the Java property [font=courier new]user.country[/font] to [font=courier new]DK[/font]. Under Mac OS X, this can be done by editing the Info.plist file found in Sweet Home 3D.app/Contents and adding the lines: after the last line that ends with [font=courier new]</string>[/font] (in version 5.2 this should be at line 248).