Hey, I'm wondering if a short solenoid (50mm) would be able to pull a 300mm core through it if it was open at both ends? Or would the soleniod stop acting once the core had come to the far side? I've attached a pic of what I'm trying to do (forgive the paint drawring). I'm basically trying to have a solenoid that I can control the position of by varing the voltage (by pwm). 1.) Can anyone tell me if this wont work? 2.) Where can I get some basic info on how to calculate the force I'll get out of it? I looked here: www. ledex.com/basics/basics.html but it wasn't amazingly helpful for formulas, and I can't seem to find any on this site. 3.)The page I referenced in 2.) said that does this mean that a tapered core would provide more force as it got thicker? What does it mean that the effective air gap changes to become a fraction of the actual stroke? Does the air gap have a relationship to the stroke that can be achieved? Thanks heaps for any help, these forums are fantastic. Phil.