Hello, I am a hobby machinist and also an EE PhD student. Recently I have been trying to make powerful solenoid actuators. I have succeeded, but they aren't perfect. I really want to make a professional, powerful solenoid. To give a sense of how deep I am going, here is what I have found so far by trial and error. (My question is at the end) 1. The solenoid must be in a housing of high permeability (in my case, I chose cast iron) so that the magnetic flux has a small reluctance and therefore increases the inductance of the solenoid and therefore the force. The plunger must also be high permeability. 2. The tolerance between the plunger and the housing must be as small as possible, as the smaller the gap the smaller the reluctance and greater the force. What I DON'T know, is how does the neatness of the windings come into play? Do they? What I mean by that is, if I were to wind the coil very neatly, laying one wire right next to the other perfectly, does that make a difference? How? What I have been doing is making my spool on the lathe, and then just winding the wire around the spool (semi) randomly while the lathe is on. My other question is, what is a good source to read about solenoid actuator engineering? I found some design equations online, but I would rather have a rigorous mathematical analysis.