Andy Pugh wrote: > On 22 September 2010 02:50, Jon Elson <[email protected]> wrote: > > >> Solenoids are not generally linear devices. As the armature is pulled >> into the >> coil, the magnetic field becomes stronger as the air gap shrinks. >> > > Doesn't this depend on the design? If it is a pure solenoid the > air-gap is constant, but the > amount of plunger inside the coil varies in a linear way, which may be > (but probably isn't) compensated by a linear spring > OK, you expressed it more accurately! Yes, the amount of plunger is the variable in that type of solenoid. Yes, with some careful design, it might be possible to set up a spring that nearly balances the change in force, and their design might do that. > This is not the case for the typical relay-style electromagnet (also > often called a solenoid) where the core is static and attracts a > moving arm. > Yes, the typical relay-style swinging armature solenoid is probably far more non-linear than the plunger style.
Anyway, I'm sure this LPKF engraver will do FINE for engraving, and may be able to drill the larger holes. I hare REAL doubts that it could possibly drill .020" holes, unless there is a dashpot or something to limit the initial velocity of the stroke. I have done drilling with an air-bearing spindle and .018" drills on my Bridgeport http://pico-systems.com/wwspndl.html and it worked great with tightly controlled feedrates, but I'd hate to just slam those small bits into the board. Jon ------------------------------------------------------------------------------ Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
