Cannot use project contributors files

Whenever I try to use files generated by those in the projects section they always carve in the wrong areas. I had no success using the Card box files and have had no success using the guitar files that were provided. The last debacle was trying to cut out a guitar neck. the headstock started carving in the middle of the mdf stock… not even close to where it should have been.

I have never tried any of these projects, but what link in particular I can go and test one of them real fast on some scrap see what I get here.