On Friday 19 August 2016 23:16:47 Gene Heskett wrote: Had to quit for much of the rest of the weekend, need some steel, and TSC doesn't satisfy my hunger with their crappy hot roll.
But I've a question, based on what I know about steppers. That 1600 oz/in I took off the mill that was falling over at 30 ipm going up is being a puzzle. The 9x0 oz/in I put on in its place has no problem with 90 ipm. But I wanted to see what might be its limits just laying on the table, with the same 60 volt psu, and the same DM860 driver. I hooked it all up and drove it with my function generator. At 100 revs, it could run the rotisary spinning this house. So I cranked up the kilohertz, after setting the DM860 for its nameplate rated 3.5 amps. and a /16 divisor. That label on the DM860 tries to fool you, its minimum divisor is 2. It finally stalled at 150 kilohertz! By my calculator, that is at least 20x what it could do as the z drive on the mill. I did have to sneak up on the frequency above 20 kilohertz, but that was way faster than it could run on the Z axis of my mill. I suspect a properly configured lowpass placed in front of the PID could make quite a difference in its ultimately attainable speed. Spinning that yard and a half long 2505 screw at 1/1 should be a piece of cake. Just don't expect that the saddle and screw are zero inertia. This is obviously bigger iron. But this new apron will weigh, even with the X motor on its rear face, likely 10% of what the OEM apron weighed, and that cannot help but help overall.. That I expect will seriously cause excess over shoot getting turned around when rigid tapping. A lag in the turn around at spindle reversal would I hope, throw a following error. One might use a rising following error to reduce the spindle accel allowing Z to catch up. That would be the ideal I'd think. Just shutting it all down will stop Z ok, but the chuck etc will still coast enough to bust the tap, and that is not a desirable result. Question: How will the following error be handled in a G33 or varient thereof? Or is that a never mind given the mass of an 8" chuck to be turned around gently enough it won't unscrew itself from the spindle nose? Following error should not uncouple that electronic gear lock In due time such questions can be answered, but I'd like to head off such problems before I get to the "pass" if I can. Comments? I should have that induction heater module Monday, its someplace in PA when I looked this morning. Which end of PA, I don't know. Thanks. 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
