If anyone is interested, here is the links above with the web pages translated to English.
[link=http://translate.google.com/translate?u=http%3A%2F%2Fslope-combat.de%2Fshop%2Findex.php%3Fmain_page%3Dindex%2 6cPath%3D21_42&langpair=de%7Cen&hl=en&ie=UTF8]method 1 (cutting):[/link]
[link=http://translate.google.com/translate?hl=en&sl=de&u=http://www.abdrehfaktor.de/abdrehfaktor050.htm]method 2 (sanding):[/link]