Hi everyone After three weeks I've got the latency down under 10,000 and received and installed my breakout board. Now I'm trying to get it going.
With unipolar stepper motors and 2 wire uln2003 stepper drivers need to alter the <loadrt stepgen step_type> to 5,5,5 or 6,6,6 , the step and direction to A- and B+ , and remove the <setp parport.0.pin-**-out- reset 1> command. ( thanks Andy for the linuxcnc forum of Sept 2012) I can't see how to do any of this with the stepconfig wizard, and if I just edit the BillsMill.hal file it will revert when I sun stepconf. So please let me know how I can edit this confuguration. Regards Bill -------Original Message------- From: Gene Heskett Date: 03/08/14 14:40:52 To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Linuxcnc stepper mill configuration On Friday 07 March 2014 23:06:00 Bill did opine: > Hi Gene and Andy > > I guess I'm convinced that I need bigger motors but until I see some > movement I don't want to do anything. If you want to see movement without letting the smoke out, and here I am assuming the + end of your 24 volt supply is being fed to the common centertap of all windings of the motor, you need a current limiter to protect the ULN2003 that will only allow about .5 amps to flow. IIRC from reading the spec sheet that the winding R was around 5 ohms for the unipolar version. Basically you will need to drop 21.5 more volts in order to arrive at the .5 amp current figure. At .5 amps, the 5 ohm winding will be dropping 2.5 volts. So 24-2.5=21.5, times 2 because its .5 amps, that would be a 43 ohm resistor and it will need to be sized for a wattage dissipation of a hair over 20 watts. A 50 ohm 25 watt adjustable power resistor, using most of it would be about right. Then you can apply power and see if the motor runs when jogged. It probably won't run long enough to see it jog without that current limiting resistor. > What Torque do you both Suggest The comments re ball screws vs conventional is quite valid, the ball screw moves at 95+% energy efficiency, while the conventional screw, even in ACME thread, is about 35% at best because you'll need to count the drag of the threads in the nut and the drag of the end thrust containment. And the ball screws, properly fitted will have backlashes in the thousandth of an inch or less, whereas the conventional screw and nut can wear from 3 thou if just adjusted, to 7 thou in one half hour long job. To get drive power, fairly fine threads are used on the regular screw, but the ball screws have relatively coarse threads. a single start 16mm ball screw will move the table 5mm per turn for example. Typical gains would be 2 times faster, and twice as much push with the ball screw. In short, make it work with what you have, and if thats not good enough, you "scratch the next itch". Its what I've been doing for the last 65 years since I quit school & went to work fixing these new-fangled things called tv's for a living, about 1948 or 49. Switched to broadcasting by getting a 1st phone in '62, and the rest is history, working the last 18 years that I worked as the Chief and often only engineer at WDTV. > > I'll carry on with calculations in the meantime then I can shop around. > > Thanks again > Bill > Cheers, Gene -- "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> NOTICE: Will pay 100 USD for an HP-4815A defective but complete probe assembly. ----------------------------------------------------------------------------- Subversion Kills Productivity. Get off Subversion & Make the Move to Perforce. With Perforce, you get hassle-free workflows. Merge that actually works. Faster operations. Version large binaries. Built-in WAN optimization and the freedom to use Git, Perforce or both. Make the move to Perforce. http://pubads.g.doubleclick.net/gampad/clk?id=122218951&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
