On Wed, 2008-04-16 at 21:37 -0400, John Kasunich wrote: ... snip > It sure looks like a unipolar drive to me. They are probably doing > half-stepping, which would give you the counts per inch that you think > you have. > > Power is applied to the two center taps, thru two of the transistors > which probably act as choppers to control the current. The other four > transistors connect the ends of the windings to ground. If you call the > windings 1 and 2, and the two ends of each winding A and B, half > stepping would be something like so: > > 1A only > 1A and 2A > 2A only > 2A and 1B > 1B only > 1B and 2B > 2B only > 2B and 1A > repeat > > That is one full electrical cycle, four full steps, eight half-steps. > > It might be enlightening to trace out as much of the power circuit as > possible and post it, if you are interested in reverse engineering the > drive. I've done a little power electronics, and I'd be happy to take a > look and see what I can figure out. > > Regards, > > John Kasunich
I believe I read somewhere that half stepping has an uneven torque profile because sometimes there are one and two coils active. The inputs I measured (full step?), always have two active. From previous posts, it seems microstepping is much better. Does anyone make a unipolar microstep drive? Is anyone using EMC2/HAL to control holding current? -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC lathe, Bridgeport mill conversion, doing XY now, Zubal lathe conversion pending Craftsman AA 109 restoration Shizuoka ST-N/Bandit CNC) ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
