On Saturday, February 19, 2011 10:57:11 am cogoman did opine: > > From: gene heskett <[email protected]> Subject: Re: [Emc-users] My > > first wiki page > > snip > > > I must say also that since the complete step is now handled in one > > cycle of the base thread, I haven't noticed my motors playing tunes > > as they change speeds, it is MUCH less obvious, and that has opened > > up another octave on the maximum speed for me. In fact, I have > > slowed my base thread to about half of the maximum my box can do > > without appearing to effect its performance at driving the machine. > > Its quite happy with a 50 u-second base thread, which in turn makes > > the video back plot in axis a lot closer to real time. That elderly > > mobo can be pushed to under 25 u-seconds but other things like the > > video get pretty laggy then. > > > > -- Cheers, Gene > > I'm just curious about what stepper motor controller you use that allows > quadrature input. It seems step pulses, whether step/direction, or step > up/step down are the common interfaces. I would think that quadrature > makes a whole lot more sense. > No quadrature input. Pure step/dir at 8 microsteps, xylotex 4 axis drivers.
Where did I say I was using quadrature drive? Perhaps I should have said "step true, wait 3 u-s, step false in one base thread cycle" above? The xylotex, like most microstepping drives, does have one glaring fault that I have not given a lot of thought to, and that is the a home operation can and will displace the motors up to quite a few microsteps as it places the motors into a known phase sequence that can be as much as 2 full steps as the motor is homed from where you just carefully set it with a dial indicator. For the levels of accuracy I need, it is not normally a huge problem because my screws are 20 tpi acme's on the x/y, and 10 tpi with a 17/42 geardown on the Z. Because of that effect, it would be nice (hint, hint) if we had the option of not forwarding that reset pulse to the drivers because then we could truly home where its at. A minor detail for most. And in day to day operations, keeping backlash current is probably a larger problem. The split nuts used in that el-cheapo mill leave _much_ to be desired with the very high wear rate of the adjustable part, and that will likely be the target of a better design eventually. Or buy a better mill. I am studying the Grizzly catalog, but will probably just drive up and take an in person look at some of their X3 like offerings, the new catalog has several additions. ;-) Its about a 500 mile round trip from here to the Lycoming Mall in PA, east of Williamsport about 20 minutes. OTOH, I need a bigger lathe I can cnc too, and that youtube of the homemade one is quite neat. That thread cutting was very impressive. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) <http://tinyurl.com/ddg5bz> "What are we going to do tonight, Bill?" "Same thing we do every night Steve, try to take over the world!" ------------------------------------------------------------------------------ The ultimate all-in-one performance toolkit: Intel(R) Parallel Studio XE: Pinpoint memory and threading errors before they happen. Find and fix more than 250 security defects in the development cycle. Locate bottlenecks in serial and parallel code that limit performance. http://p.sf.net/sfu/intel-dev2devfeb _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
