Because 20 TPI has been a standard for manual machines for years. Also, most small machines aren't designed for scarey rapids, so there was no need to change to a more expensive solution.
And finely, microstepping does not improve accuracy only resolution. For a 200 step motor and a 10TPI you can get 1/2 thou accuracy compared to 1/4 thou accuracy with a 20TPI leadscrew. Whether the small machine can take advantage of the exta accuracy is another question. :) --------------------------- Peter Homann http://www.homanndesigns.com/store On Tue 17/04/12 11:45 AM , Dave wrote:On 4/16/2012 9:28 PM, Jon Elson wrote: > Kirk Wallace wrote: > >> >> Most of the components on the G540 are SMT and too small to have >> markings, so I could only guess about what they are. I have some close >> up pictures of the area in question, but my camera's cable has woken up >> and run off somewhere. I'll post the pictures when I get this sorted >> out. >> >> > Most of those tiny parts have a 2 or 3 letter code that can be looked up to > tell what part it is. > >> On the other hand I'm thinking I'll need to deal with the G540 as it is. >> >> I'm still concerned that the G540's 10x microstepping would put it out >> of the parallel port arena. It seems a 5i25 would be more appropriate, >> plus taking into account other savings the 5i25 might provide, might >> make it cost similar to a PCI parallel port and buffer board. Trying a >> Pluto-P is on my to-do list. >> >> > Right, 10X microstepping on small motors with fine-pitch leadscrews end up > needing a fast step rate. Assuming 2000 (micro) steps per rev, and wanting > maybe 30 IPM on a Sherline or Taig with a 20 TPI leadscrew, that is > 30 * 20 = 600 RPM or 10 RPS. 10 RPS * 2000 = 20,000 steps/second. > This is doable with software stepping, but near the limit. And, the step > timing becomes jumpy at the high end. It is barely humming for a hardware > step generator, however. They can easily go ten times faster and more. > Well, maybe you will have luck with the Pluto, but others have had > problems with it. > > Jon > > > True, but even little Nema 23 steppers have little usable torque beyond 800 rpm unless you go with a high voltage stepper drive (which the G540 is not). Larger Nema 34 steppers are pretty useless beyond 600 rpm or so. Why do they use such finely threaded leadscrews? I would think that 10 tpi would be more reasonable. Dave ------------------------------------------------------------------------------ Better than sec? Nothing is better than sec when it comes to monitoring Big Data applications. Try Boundary one-second resolution app monitoring today. Free. http://p.sf.net/sfu/Boundary-dev2dev [1]" target="_blank">http://p.sf.net/sfu/Boundary-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users [2] ------------------------- Message sent via Atmail Open - http://atmail.org/ Links: ------ [1] http://p.sf.net/sfu/Boundary-dev2dev [2] http://webmail.homanndesigns.com/parse.php?redirect=https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Better than sec? Nothing is better than sec when it comes to monitoring Big Data applications. Try Boundary one-second resolution app monitoring today. Free. http://p.sf.net/sfu/Boundary-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
