On Wednesday 29 April 2020 01:10:54 John Dammeyer wrote: > > If using the parport in EPP mode, you can set a reset time > > separately, so you can step at the base thread rate. As far as motor > > speed is concerned, the speed limit is generally the speed limit of > > the opto stuff in the driver, and I've run steppeers laying on the > > table at slightly better than 300 kilohertz with a 2M542 driver, or > > about 3000 rpm. zero torque at that speed of course. :) > > > > > > Cheers, Gene Heskett > > Hi Gene, > I'm just in learn mode trying to figure out how LinuxCNC works. Not > worried about speed. So far, with various steppers when actually > used to drive machines I've found that if you can step at 20kHz you > are way beyond the torque capabilities of the motors. John > This is also true John, its the nature of the beasts. In fact one machine I own, a 6040 that came with crap electronics I had to replace all of, has a batch of the shortest nema 23 motors I have seen. But with a box of good drivers its doing rapids in the xy at 200 ipm. The Z has to lift the horse or so spindle motor so its all done at 35 ipm going up, but the little motors have much less inductance so they will take the needed currant at higher speeds where the 435's on the g0704 mill are all done well before 100 ipm.
Either. at working speeds has more than enough torque to shatter a plugged up with hot alu tool in a heartbeat. I very quickly found that mist cooling on that puppy was an absolute requirement so I invented some, I am pulsing a peristoltic pump, similar to what the hospitals use to put an IV drip in you. Pulse is settable from the axis gui. Air for it is also switched by the same button. I've also found that the proper programming of the vfd's can get enough power to cut alu at a quite decent feed rate even when that 24k revs spindle is only turning 1k revs, the secret is to set the low speed currant limits in the vfd to match the motors FLA rating. They don't come OOB set to do anything like that. Thats not always easy when trying to translate the vfd booklet, written in Chinglish, to something you and I might understand. But I've done it twice now with amazing low speed results. My converted Sheldon lathe, with a 1 horse 3 phase that spent the first 40 years of its life on an air compressor, can pull large swarf turning blue, when driven at 8 hz, for long enough to get the job done, without getting the motor too hot to lay my hand on it. Flat, plumb, hasn't been used yet, don't need the backgear. 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
