On Thursday 10 December 2020 04:51:33 andy pugh wrote: > On Wed, 9 Dec 2020 at 23:13, Gene Heskett <ghesk...@shentel.net> wrote: > > I noted that 1 turn of the bs-1 worm is exactly 10 degrees > > I would be surprised if that were the case. I think that dividing > heads are either 40:1 or 90:1, and the docs for the BS1 say it is > 40:1, or 9 degrees per rev.
Probably, I was turning the worm with a 4" crescent wrench. > It would be better to count full turns of the input shaft against a > full chuck rotation to be sure. I have hal code that will count 100 turns, using the home switch to count turns. But that means I'm playing with SWAG's for SCALE while trying to get the ballistics close. And there is plenty of friction in his. Takes at least a 15% duty cycle to get it to move but will run on 8 or 9% once started. Pgain is interstellar of coarse > > idea of measuring one turn of the motor, hard to do without a long > > pointer, but came up with about 20 counts shy of 6000 for one full > > turn > > Again, it is more accurate to measure 10 (or more) full turns and > divide. 6000 is an unusual number of counts (but not as unusual as > 5980) No argument there. > > Obviously wrong as can be, so that seems to be a scale not for 1 > > turn of the bs-1 but the right scale then is for 1 degree of its > > rotation? > > Yes, the scale is the ratio between steps or encoder counts and > engineering units. > If you are using degrees, then it is steps per degree. Of course you > could work in radians, but the scale would be irrational. I just knew there was something wrong with it. > > When I used the rotary table, scale is stepper micro-steps for one > > full turn, and I can tell it to go in 90 degree steps while making > > tap hats, and its right. So why is it not the same "unit" for a > > servo? > > Did you program the rotary table in fractions of a turn or in degrees? I programmed its movements in degrees. But it seems to me that the scale was in micro-steps for a full turn. I didn't have a home switch on it early on, and when I did put one on it, and counted 100 turns. I was well within .1% with my wild guess. That was obtained by repeatedly moving it CW by 360 degrees and adjusting the scale until it stopped again on the 0 mark. Anyway it looks like SCALE will be 1 degree. Any higher and its obviously moving too fast. 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
