On Monday 16 December 2019 16:26:47 andy pugh wrote: > On Mon, 16 Dec 2019 at 20:10, Gene Heskett <[email protected]> wrote: > > https://www.cnczone.com/forums/uncategorised-metalworking-machines/1 > >72 > > > > >314-cnc.html > > > > No, but the lack of a geardown makes the step a major portion of the > > error, whereas the use of a much smaller stepper with 8/1 or better > > on that proposed center shaft should turn the steps so slow as to > > have the steps disappear into the general mechanical noise. > > My conversion used a little (NEMA23) servo rated at 25W and much less > torque than a comparable stepper. It had enough torque for most jobs. > A stepper would have had plenty of torque. > 90:1 worm ratio means a full step is 0.02 degrees. That's not a lot. > And then a bit of microstepping on top would be fine, I think.
My thoughts exactly. Turning it under cutting load, if its anything like my toy 4", will take more power, or a decent reduction drive like I have in mind. I've a 435oz nema 23 on it now but I also have the thru bolt tighter than normal because I had visions of pressurizing it to lift the pressure off the rim, works well but never got around to putting in an air valve to control that "air bearing" pressure. I did mill a 1/16" wide groove in the base castings rim face that serves as the air distribution. Basicly I just got tired of fighting with it, although it worked well for drilling and tapping the tap hats for grub screws to hold the tap by its square butt. But it had trouble makeing a big 3 flute bit when I cut a hole for a chair ramp in the front deck 18 months back, had to take pretty light cuts making flutes with a 1/4" ball mill. And changed the cut direction so the cut helped, so the cut was pulling it. Then it worked well. Made a dozen holes at high angles in the sides of 3 4x4's that have a 4" plastic post cover over them, planted in a big puddle of tight-bond-III with a fascia bolt running downward into the holes and on into the deck. Posts still are as stiff as if the were planted on concrete yet. 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
