On Tuesday 15 December 2020 05:59:34 andy pugh wrote: > On Tue, 15 Dec 2020 at 00:36, Gene Heskett <[email protected]> wrote: > > So the last attempt was only for ten trips past the home switch. > > That kept the halmeters out of sci notation. Tracking the encoders > > rawcounts with two sample-holds, first freezing the rawcount at the > > first switch passing, the second freezing the raw count at the 10-11 > > transition. Then subtracting the first from he second gave 2400114 > > rawcounts difference. > > This is _much_ more likely to be 2,400,000 than 2,400,114. (The answer > must, at the very least, be divisible by 10)
I wondered about that, but didn't come up with that particular reason, and its a good one. Given the contact bounce of a 34 cent microswitch, and the latency timing jitter since the switch is moving relatively slowly I certainly won't argue the point. The question then becomes "how many 6's do I put to the right of the decimal in the ini file definition?" > So your scale is probably 666.666666666666666666666666666666 > > Not that the difference in the numbers is likely to correspond to any > significant error in the parts. Extending this same reasoning to that 666.666666forever line of thought, and knowing that 1 full turn of the worm is exactly 9 degrees since its a 40/1 drive in the BS-1, can we further refine it to an even integer number? Leaving only the mechanical errors in grinding the worms and bull gears since they are going to be cyclic AND synchronous averaging to zero error at any one point in the 360 degree rotation. From the variations in drag as its turned by hand, there is obviously some eccentricity in the BS-1 bull gear and in the BS-1's worm. And I can also see a cyclic variation in the effort the pwm is exerting on a scope watching the pwm width and it seems to correspond to the internal gearing of the motor. Its encoder HAS to be an integer per its armature turn, but is an unknown, not specified, but both the encoder and the motors internal worm gear ratio have to be integers. I could fine tune that by running it more turns but eventually the halmeters switch to sci notation displays so my usual 100 turn measurement isn't possible due to that rounding. 20, maybe 30 turns might be possible, but by 50 I'm looking at sci notation displays. And the way its mounted on the mill as I am drilling and tapping for mounting bolts precludes putting the indexing disk on it, so I am totally dependent of the home switch and its vagaries for this 1 turn index ATM. 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
