Michael

you are right about the size of the fillet i was trying to make.
Thanks for the tip about modeling at a bigger size. I work with modo as polygonal modeler and this it the opposite. it's better to model to real world scale.
Just so you can have a look if you need i join a picture of the part that is causing trouble for the file i uploaded before






Laurent

ps: i just try with unity as centimeters but result is the same. i'll give it another try tomorrow. Thank you very much for your support :)