Hi there, before all excuse me for my poor language, i'm not native English speaker, so sometimes it's difficult to express my self. The thing is i'm building a homemade weight measure machine (i don't know the exact word for it... :grumpy:) the idea is that it can hold a 5kg mass over it. like this: http://img62.imageshack.us/img62/4861/solenoid.jpg [Broken] So my main problem is how to calculate the Solenoid (calc its number of loops, height, its amps, ect) so it can hold a 50 Newton force. Do you get my point? All help is welcome. Thanks. Brian.