On Saturday 15 August 2020 15:09:19 John Dammeyer wrote: > Hi Gene, > > > Thats a pretty tall order, John, and we both know it. Looking at the > > various *-pi's, some of which are actually driving machines quite > > well, some may not think these are a pc, but despite their credit > > card size, they ARE a pc. I don't know exactly what Bari is doing > > with his *.pi, but if you take inventory of everything I am doing > > with this rpi4, I think most will be impressed. I'd go so far as to > > say amazed. Cutting air making 50 copies of the chess pawn with that > > rpi4, I went online with firefox, fully expecting to see it screwing > > with my exercise, but in an hours worth of browsing the network news > > sites, I did not detect a single instance of the lathe stalling. > > > > So the next thing is to establish just exactly what is wrong with > > linuxcnc running on some flavor of processor which is running linux > > that may have been compiled using the linux tools of that processor > > family. > > > > So lets see if a waterproof argument can be made. > > Couple of simple questions for you Gene. > 1. Photo of your Pi setup please so we can see how tiny your setup > really is. 2. The Pi doesn’t have enough hardware I/O to directly do > CNC with 5 Axis along with MPGs and Spindle Encoder so how are you > interfacing to your motors? > > John Dammeyer
Its big and bulky as I started about 5 years ago with a Mesa 7i90 and bad grounding, too many loops generated enough noise I destroyed the 1st 2 7i90's, So I cleaned up my grounds AND invested in 3 7i42TA's which helped the wireing immensely, and gobbled up the remaining noise, but the Mesa bill was up to a bit over 200 bucks by then. Bulky because the pi is upside down so the 26 pin header had a short direct shot at the bigger 7i90's 26 pin header, so there's only maybe 1.125" of cable between them. The 7i42TA's are stacked like stair-steps on top of the 7i90. That 7i90 is damaged, stepper out #0 is no more. Pix are someplace in the list archive. And may show a pi3, but its since been swapped for a pi4 with its many times faster video. Extras carved out of hal's bits and pieces include two 100 ppr quad encoded dials that hal reads as step commands ranging from .0001" per step to 50 thou a step, with a mode pushbutton beside the dial so the dial is its own jog size control, so I can drive it from those dials by hand just as if the old cranks were still there. Home switches too, all machine power slaved to 40 amp SSR's which are driven by the state of the F2 key, and the alarm from the new z stepper-servo that kills F2 and unhomes the machine if tripped. That and some tracking stuff in hal reports how far it overshoots on a rev command, and if the gcode uses that feedback, can display the overtravel distance in thousandth's in the pyvcp panel. With a nearly 40 lb 8" 4 jaw mounted, at 100 rpms, its a tad over .25 turns to reverse it, so rigid tapping works fine. Pretty good for a vfd. Clamps on the back of the backing plate hubs make sure I don't unscrew the chucks doing that. So this nearly 80 yo service truck lathe is now doing tricks the folks at Sheldon never in their wildest dreams ever thought a lathe could do. And yes, I'm proud as hell, doing all that with a pi3 at first. I even comped most all of the bed wear out with lincurve. 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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
