On Sunday 10 December 2017 07:24:06 Les Newell wrote: > On my lathe the gearchange is automatically controlled but it behaves > in a similar way. If I tell it to change gear it commands a low speed, > waits for the spindle to decelerate then changes gear with the motor > turning slowly. It then winds back up to the commanded speed. I did it > mostly with ClassicLadder. There's quite a lot of ladder logic on this > machine. > > Les > I have a limit3 in that chain whose job it is, is to convert hard changes in the reversals and such into a sine squared shape. That slows the reversals, such as at the bottom of a hole when running a G33.1, into something the z axis can track. This thing can do a reversal in high gear at 300 revs so fast that Z can't follow it. I put that in originally when the Z motor was a 1600 oz/in and would stall at 28 ipm lifting that much weight. But a smaller 960 oz/in, with an ac powered driver turned that into about 80 ipm. And it turned out that it was much faster as Z on the Sheldon. X is only half that, but generally X doesn't have to move as fast as Z, so 38 ipm is fast enough. Fast enough at the entrance and exit moves for a G76 to make some nice threads. I haven't tried to do some of the tricks I did with G76 on TLM, but I expect I'd have no problems doing them. The X screws drive is a new shaft thru the crank bushing screwed into the carriage, with a 50 tpi thread on both ends of a piece of as shipped A2, but the thread on the rear has a one thread depth taper on the last 5/8" that blends into a straight thread, give me a place to put 2 nuts on it which set the endplay to a slight preload on the hard needle bearings for thrust washers. That last, tapered section was bored for a push fit on the X ball screw so when the end of the screw is inserted into the bore, and I slit the end with EDM, much thinner kerf that way, makeing 6 petals out of it, and a 3rd nut, bored 50 tpi threads to match that taper then used to compress the bore onto the screw. And a bunch of green locktite slathered onto it. Overall backlash is under 2 thou.
No docs & no clue what the tpi or tpmm on that screw is, so I just adjusted the ini files "scale" until a commanded move of an inch was well within half a thou of an inch on a dial. I also put a pair of needle bearings in the hushing but it had enough wear that they aren't that tight, but the motor appreciates the freedom to spin, its a nema 24, 8 wire in parallel, for low inductance, with an M542 driver running at full current on about 42.5 volts. 2/1 pulleys there. Maybe by the time I need to pull that piece of A2 out again, I'll have rigged up a heater so I can harden it. One of the advantages of doing the slitting with EDM is that it leaves no burrs to screw up the fit. It also taught me that for that, distilled water is a better dielectric than K2. All this keeps me out of the bars. > On 10/12/2017 01:44, Gene Heskett wrote: > > Greeting; > > > > But now I've violated one of my basic premises in that I did have a > > limit setup to keep it from going above a 98% duty cycle, but thats > > now broken for both speeds. > > The snow is just enough to color the grass, and that copy of the old hal file, on dead tree, is out in the garage yet. But first I fix my woman something for breakfast. Priorities... > > So now I take a year old printout, and compare it with a fresh one > > and see where I broke it. > > > > But all the hal code, with this exception, is working as I intended > > it to work. The spindle speed also seems many times stiffer than > > before, using an FF0 = 1.000 and an Igain much less than .01 so far. > > Thats a MAJOR improvement. And the gear shifting help by running the > > motor at 15-20 rpms when the knob is not seated in a gear, but is > > turned on means I can dial up a thousand revs, reach over and change > > the gears as the motor is slowed to a creep long before the gear is > > disengaged, and slides right into mesh in the other gear with the > > spindle coming back up to 1k rpms a few milliseconds after the knob > > is seated under that switch. The pid_s is disabled on purpose during > > the gear to gear transition, so theres no windup to unwind. Sweet! > > Cheers Les, 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> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
