You might take a look here for stepper motors. http://web4.automationdirect.com/adc/Shopping/Catalog/Motion_Control/Stepper_Systems/ Motors_-z-_Cables
I see they have some new ones and they are very cost effective. John On 19 May 2009 at 11:00, Michael Jones wrote: > Interesting, these motors are HUGE for floppy drives and such? > > I'm looking into replacing the motors with something MUCH more > efficient however, until the budget allows, I'm kinda stuck with > these > for now. In the meantime, I'd like to at least make the current > system work as efficiently as possible. The question is how do I > figure out the correct timing for the system as is? > > I've been looking at some of the NEMA23 motors from: > http://www.kelinginc.net/index.html > at around 300 oz-in. I figure they will be MUCH better than the > 83 > oz-in with the high resistance/voltage and such. > > The current stepper drivers are L297/98 based and I'll probably be > keeping these as Geko's are kind out of my budget right now. > > > > Thanks, > > - Michael > > > > On May 19, 2009, at 10:03 AM, Jon Elson wrote: > > > Michael Jones wrote: > >> My mill seems to be working OK, with decent speeds and feeds - > though > >> I'm getting intermittent missed steps on the fast rapids. I'm > still > >> kind of fixated on making these motors do their best - maybe I'm > just > >> tilting at windmills, who knows. > >> > >> I just located some specs on what I believe to be the motor and > >> control setup on my mill. It appears to be a Vexta PH266 > series > >> motor with Thompson L6203 driver chips. > >> > >> I don't know exactly what I am looking at here and if or how > these > >> values combine into what EMC needs to optimize step length and > >> timing. > >> > >> > >> Current: 0.6A/phase > >> Voltage: 12 V > >> Resistance: 20 ohm/phase > >> > > Ugh! You are sunk! These are very high resistance and > inductance > > motors. They were designed for use in floppy drives and such, and > the > > current limiting resistor is the motor winding itself. They > will > > perform quite poorly, and can only do a couple hundred RPM at > best. > > Motors designed to give good performance will have resistances of > 1-2 > > Ohms, and voltage at rated current of just a couple volts. These > > motors > > work VASTLY better even with mediocre drivers like the L6203, and > can > > deliver usable torque at over 1000 RPM with a good driver like a > > Gecko. > > > > Step timing has to be right for the driver to function correctly, > but > > you are not going to improve perfomance by tweaking the step > timing. > > > > Jon > > > > > -------------------------------------------------------------------- > ---------- > > Crystal Reports - New Free Runtime and 30 Day Trial > > Check out the new simplified licensing option that enables > > unlimited royalty-free distribution of the report engine > > for externally facing server and web deployment. > > http://p.sf.net/sfu/businessobjects > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > -------------------------------------------------------------------- > ---------- > Crystal Reports - New Free Runtime and 30 Day Trial > Check out the new simplified licensing option that enables > unlimited royalty-free distribution of the report engine > for externally facing server and web deployment. > http://p.sf.net/sfu/businessobjects > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
