On Tuesday 25 June 2019 05:21:52 Erik Christiansen wrote: > On 25.06.19 04:02, Gene Heskett wrote: > > Perhaps you have forgotten that the ER style nut is a loooong ways > > from symmetrical internally? > > > > My guess is that the spindle is balanced w/o the nut, and that the > > nut is separately balanced. Or should be... > > +1. The angular position of the tightened nut will depend on brawn, > spanner length, and where in the ER collet's 1mm tolerance the tool > shaft diameter falls, I figure - i.e. it'll end up anywhere. > Absolutely. And in the ER32's turning 3G's max in my G0704's abused spindle, balance is not a prime concern, but in an ER20 where you expect to hit perhaps 15k revs, or in my 6040 with its ER11 turning 24k, a few milligrams can destroy the motors bearings eventually. I have both in the 1.5 horse pen, but one is air cooled and one is water, so the air cooled won't fit in the water cooled mount. And I'd have to drill new holes in the slider to take the other mount, so I haven't tried it. Except for the shh of the air, the air cooled one is smoother and quieter, virtually zero humm, indicating to me that its very well balanced. But with the water cooled one, I can program the vfd to use a slower minimum speed, with more amps and still have power enough for a 2 flute bit in wood or thin alu at 4G's and 15 or more ipm. So far, the hottest I've ever seen on an lcd strip on that motor is 33C, while the strip on a 4 gallon tank is showing 31C. It all depends I think on the vfd driving it.
I gave up on what came with the 6040 for the vfd, and bought a clone I can run with a 7i76 but its different from the clone on the sheldon, and harder to program because of the poor engrish translation in the booklet. I've got it running fairly well but since the motor doesn't list the FLA, you raise the lower speed amperage slowly. To add further insult, its a 110 volt motor. I have it rigged so an amprobe can be used to watch it, but none of the toolbox amprobes I have claim a wide frequency range, so at 20hz, or 200hz, you have no clue if its even +- 50% of whats its telling you. They are calibrated at 50 or 60 hz, so keep that in the back of your mind. The only true rms reading you will ever get is from a meter that is basically a bolo-meter, and is actually measuring the temperature of the shunt. Old 6 volt auto headlamps in series with the motor would work better by measuring the brightness of the lamp due to the current passing thru. That, if well shielded from ambient light, can't lie to you, its a perfect rms conversion you can calibrate with a dc current. > Erik > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users 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
