On Sunday 27 July 2014 01:27:48 Russel Ingram did opine And Gene did reply: > Yeah, I know I could hardwire it to work. I would rather not. > Especially since the software is capable of doing what I want, at > least with other drivers. If I can do it in software, the cabling is > much simpler. Thanks for the suggestion, though. > I tend to have an urge to "simplicate" things. :) The only other comment I'd make is that with the torsion springiness of having two motors whose resonances might add up at certain speeds, would make dampers on the rear of the motors seem like a good idea. With single 225 oz motors on the XY of my mill, I doubled its speeds with some dampers I made. They are visible in some of the pix in the emc link on my web page in the sig. However, if I make any more of that type, I will use alu for the spool. In a pinch, the rubber disks could be made from a truck tire inner-tube, but somehow, about the time I was contemplating making those, I stumbled over a flat sheet of 1/8" rubber at a yard sale in a neighboring town. The steel washers are the biggest fender washers I could find at Tractor Supply, and I turned the spools shank to just fit them. I'd go alu for the spools next time because the weight of the steel probably has an effect on how much accel I can use without a stall. Stepper motors are fickle beasts in that regard.
I also blew several of the xylotex boards, and went shopping on ebay, buying 7 of the 2M542 drivers, 4 for the mill and 2 for the lathe & one spare, still in its box 3 or 4 years later. About $50 a copy at the time, and seemingly bulletproof. I had one shut itself down to protect itself in that time. Took a powerdown to reset it. Otherwise they've Just Worked(TM). Rated 4.2 amps and 50 volts, not recommended below a 24 volt supply as lower voltages = more heat. 28 volts on the mill, and about 37 volts for the lathe. Those on the lathe run noticeably cooler. Surplus iron for the power tranny is hard to find in that voltage/current range. All of these drivers, including the xylotex need a goodly amount of capacitance in the psu output circuit because they recycle the current regulating chopper currents back into the psu, and poor capacitors can let that result in a ripple voltage at the chopper frequency that can easily exceed the a3977's voltage ratings, and that lets the smoke out instantly. So my last home made psu for the lathe has a choke input filter, and around 30,000 uf as output filter in the form of a triplet of 10,000 uf, 35 volt cans whose tops are gooped to the floor of the box its all in. The choke input lashup results in a much more stable output voltage as the loads vary, unlike using a huge input cap in a pi section filtering scheme would. The power transformer runs cooler too because those huge current peaks that charge the cap input filter aren't there. Yeah, I'm an old fart now, looking at 80 yo in October, but in my working years I was/am a C.E.T., and a tv station Chief Engineer who didn't send anything I could get docs for, out to be repaired. So electronics are generally not a huge problem for me. Switching power supplies are quite efficient too, but not all of them on the market can tolerate a stepper motors back currents, as they will see the over voltage and shut down. One I tried to add enough output capacitance to, to alleviate that, then wouldn't start, seeing the charging surge of a 10,000 uf cap and shutting down thinking its output was shorted. BBLB stuff (big sigh). Built By Lowest Bidder. :) Have fun Russell, thats what this is all about to me, keeps me out of the bars! Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS ------------------------------------------------------------------------------ Want fast and easy access to all the code in your enterprise? Index and search up to 200,000 lines of code with a free copy of Black Duck Code Sight - the same software that powers the world's largest code search on Ohloh, the Black Duck Open Hub! Try it now. http://p.sf.net/sfu/bds _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
