On Wednesday 22 September 2021 00:27:53 John Dammeyer wrote: > I love it when a plan comes together. Tested out the Bergerda 1.27NM > motor on the Y axis. I was worried that it might not carry the extra > weight as the DC Servos were 1.6NM. > > Well. Silky smooth. For a 2.8A motor it never has more than about > 1.0A current draw and about 0.34NM based on what the servo drive > reports. Sounds nice too. And that's with two heavy vices and a > rotary table all the way up to 3000 RPM 4:1 to 0.2" pitch ACME screw. > > Time to put the other one on the X axis and verify that the positions > remain accurate. > > John
I'm surprised you kept the acme screw. I used a stationary acme as z on my hf micromill, first mill I cnc'd. with a rotating nut design useing two nook nuts. Had to adjust the phases of the 2 nuts to keep the backlash under 5 thou, several times a year. First thing I did to the bigger G0704 was put a ball screw kit in it. Never looked back, 5 years later backlash is still under 2 thou. Now my biggest problem is that the post isn't plumb. So its impossible to tram correctly. But my garage is full, no room for a bigger, more accurately cast nachine. > > > -----Original Message----- > > From: Bari [mailto:[email protected]] > > Sent: September-18-21 11:30 PM > > To: [email protected] > > Subject: Re: [Emc-users] DC Servo issues > > > > On 9/19/21 00:44, John Dammeyer wrote: > > > Over 10 years ago I bought two of these for the XY axis of the > > > mill. > > > https://www.automationtechnologiesinc.com/products-page/dc-servo-m > > >otor/nema34-1125ozin-dual-shaft-servo-motor > > > > > > One of the things that showed up right away was that with > > > identical drives one motor ran hotter than the other. Further > > > > investigation showed the resistance of the windings was different > > with the warmer motor having the lower resistance and inductance > > which matched the spec sheet. By then it was too late to return the > > high resistance one so I decided to put what appeared to be the on > > spec motor on the Y axis since it had to carry more weight. The X > > axis got the cooler and higher resistance motor. > > > > > Especially since AutomationTechnologies wouldn't replace the motor > > > even though it was clearly out of spec. Not about to buy > > > > anything else from them. > > > > > > They are local for me. The owner is a nice enough guy but he also > > problems with getting reliable consistent parts from his homeland. > > > > I only buy things from them that I expect to be like a kit that > > needs to be cleaned and assembled properly before use. I have had to > > return radial bearings with detents and linear bearings with crud > > inside or flat spots. We call them crunchy bearings. CNC mills come > > with red oxide treated fasteners and without nuts on the end of > > ballscrews so you can't adjust preloads unless you shim or replace > > with proper screws. Cables are assembled without the use of strain > > reliefs. > > > > Red oxide treated fasteners� https://postimg.cc/jnhmsRhq > > > > No strain relief� https://postimg.cc/7bqwTvvy > > > > 1mm of lash� https://postimg.cc/w1bvqpWk > > > > > > > > > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > 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
