On Fri, 2008-06-20 at 21:59 -0500, Jack wrote: > I have EMC2 installed on an old Compaq iPaq desktop running Ubuntu 6.06 from > the EMC2 install CD, driving a HobbyCNC controller and gantry with Kirk lead > screws. > > When I use the sample stepper_inch config it works, but I need to tweak the > configuration some to change the stepping (thread pitch, etc) but when I try > to generate my own using the config tool in Axis, it just doesn't work. > > Suggestions? > > I figure this is probably something dumb I am doing, and I am willing to > RTFM, I just need some direction.
You might try the pitch change to your working sample file. Just edit the SCALE = XXXXXX to match your lead pitch and motor/screw ratio. This will change the step rate requirement for a given axis rate, so you might reach your stepping rate limit earlier or later. Compare the working and stepconfig file differences and add each change to the working file until it doesn't work, then research the last feature you changed. > With the sample config, it is jogging back and forth OK, but it is not set > for the right threads per inch for the lead screws. You may be stalling your steppers because the stepping rate may have changed. You may need to find the max stepping rate (not axis feed rate), then tune different settings to to maximize it. Once you find the maximum rate, adjust your maximum axis feed rates to stay below the stepping maximums minus a safety factor. > Once I get this working, next comes home and limit switches and a hardware > emergency switch. > > The latency test runs, but if I do try to use the computer, sometimes the > numbers go out of sight. 'Normally' it runs about 15000. When it goes > 'crazy' It > reads over a million. My 500MHz celeron may be to slow, but it is what I am > playing with for now. > > Thanks. ... Jack In my opinion, you need to fix the latency test problems first, so that you have a stable system that will give you more consistent behavior. Check items 2 and 5 here: http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?TroubleShooting and: http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?TweakingSoftwareStepGeneration http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Stepper_Drive_Timing Another issue that may come up with larger machines, with fine pitch screws, high (low?) motor/screw gearing or high feed rates, which translate to higher step rates. The PC parallel port tends to be too slow. You may need to consider going to a hardware step generator like the Pluto-P, Pico UPC, or others. -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC/EMC CNC lathe, Bridgeport mill conversion, doing XY now, Zubal lathe conversion pending Craftsman AA 109 restoration Shizuoka ST-N/EMC CNC) ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://sourceforge.net/services/buy/index.php _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
