On Wednesday 05 August 2015 12:19:20 Gene Heskett wrote: [huge snip] > > I have not hooked sumenc.out to pid.s.feedback yet, but sumenc.out > > is a heck of a lot cleaner than scaleX60's output. Mathematically > > it should be 4x quieter, and its at least that much quieter on the > > halscope view. It pains me to have to do all that data conversion > > back & forth, it would greatly simplicate things if sample_hold was > > float. Now I am going to hook it up to pid.s.feedback & see how much > > PGain I can use before it starts stuttering. > > Hooked up, Pgain at 500, control is stiffer than an oak timber. > Stable, but too stiff as issuing a slower s command kills the motor in > milliseconds! Then it has to be turned off & back on to reboot Jon's > servo driver. So that will have to be a compromise unless I can > restrict the pwmgen from going below 1% duty. > > Looks great at 2100 revs, very quiet output. My digital scope on the > encoders logic A/B outputs looks pretty good, so those opto's would > appear to be fast enough. > > Doesn't look so great at 60 rpms because a single quad value falls all > the way thru it at the servo-thread rate. Need to concoct a value > changed detector to trigger the sample-hold.hold's. And edge detector > won't do that, but a comp of the in vs out of the first sampler might > do it, but do I have to convert it back to float? Short answer is > yes. > > This could be tricky at the addf stage. I do not want to addf an extra > servo-thread delay. > > News at 5...
I wound up doing an s32-float with the first sample-hold's output, comp-ing that to the original input with a hyst setting of 2, which seems to be a pretty reliable way of detecting a new value from the encoder. The noise suppression is considerable even at only 100 rpm, and pid.s.Pgain is at 150. Control is very stiff, but still not rpm accurate, asking for 2100 revs gets about 2650. At the other end of the range, starting needs an s80 to get about 20 rpm. That's not too useful anyway other than I usually sense a G38.2 contact with the tool I'm using in the spindle, turning slowly in reverse so it doesn't chew up the contact guage near as fast. I also found that the Grizzly catalog has an error. On the page for the GO704, it says see page 744 for a clamp bolt set #1075, so I bought one when I bought the mill. When I pulled it out to mount the jig I made to carve those Green & Green style joints, I had to take all the T-nuts to the small mill and take .030" off both sides of the T before they would fit the slots in the table! And that chip guard thing was demolished on the first gcode run to see how it cut a piece of scrap white ash (very good, potentially 3 to 5x faster too), it was hit by one of the holddown bolts in the jig and nicely demolished by jamming the rod holding the plastic upward in its casting about 1/2". So another OSHA mandated "accessory" is history. I could see its usefulness if the spindle turned fast enough to throw swarf into the air, but at 2500, it all lands on the work, maybe 2" from the tool. That merits no more than a large, very expressive shrug from me. :) And I now have a machine with both the power, and the room to accomodate a vacuum hose to the dust collector. So that will be one of the first "accessory construction projects" once I get the electronics into their final working places and out of my way. Teeny junction boxes for cable terminations at the motors and connectors for quick disconnects on the power electronics box are still in the bowels of China Post, someplace. Question, since the motors can get quite warm, how do you fix a die-cast 1x1x2.5" box to a motor? Most modern glues tend to come apart at higher temps. And for movement space reasons I can't put it on the X motors end bell w/o moving the mill, which I think I have room to do since the furniture on the right's location was determined by wall stud locations. So that may not be a problem after all. Thanks for reading this far. > > Comments? Shoot me downs? Crickets. 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) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
