Thanks, I am planning to cut aluminum, not the hard type, I can take when cutting, so maybe I'll cut slowly, what stepper is recommended? How big should it be?
-- Youda On Fri, Sep 4, 2009 at 11:19 PM, Gene Heskett <gene.hesk...@gmail.com>wrote: > On Friday 04 September 2009, Youda He wrote: > >Thanks, that look good. > > > >Does the EMC2 tracking the actual position, assume sometimes the stepper > >lost a step or so, with parallel port communication, how does one feed the > >optical encode position info back to the computer? > > > >-- Youda > > Through the input pins on that same port, or if there are not enough pins > available, a 2nd parport card can be added to the computer. I believe > there > are enough spare pins that a quadrature pair can be had for 3 axis's > without > the extra port being needed. > > However there is a potential problem with that approach. If the stepper is > pushed too hard or fast, it will indeed lose steps, and that error will be > fed back into emc, which will attempt to play catchup, further weakening > the > motors torque since steppers torque falls with increasing speeds. So the > incipient stall is converted into a full blown stall by the feedback. > > Either way the motor will generally stall until the step rate is reduced to > near zero at the far end of the move, and the part is of course wasted. > > In my own experiments, I have found that if the machine is well lubed and > adjusted, the snappieness of movement can be sacrificed, and because the > accels are reduced, then the maxvels go up quite a bit. Faster in steel > than > my limited spindle can cut without breaking bits because the max spindle > rpm > is only 2400. I end up programming steel cuts at maybe 10 thou deep and 2 > to > 3 thou thick chips. Any more and the spindle will stall, blow a fuse or > trip > its safety off, and a $14 1/4" carbide bit is made into 2 or more pieces. > > Hard grades of alu can be cut at faster feed speeds but requires the > surface > be well flooded to preserve the finish and exclude as much oxygen from the > cut as is possible. That of course we all know. > > With steppers, it is far more preferable to stay in the bottom half of the > speed envelope where the potential for a lost step and or stalls > disappears. > If you need more speed with steppers, throw more psu voltage at the > drivers, > but currents are generally more than sufficient at 2 to 2.5 amps. Or if > there is torque available, change the gearing to get more speed. > > > > >On Fri, Sep 4, 2009 at 6:35 PM, Gene Heskett <gene.hesk...@gmail.com> > wrote: > >> On Friday 04 September 2009, Youda He wrote: > >> >Thanks, it seems most computer works, especially the Intel Atom worked > >> > well. Do we have drawings to connect parallel port to step driver? We > >> > have some Allegro chip that takes pulse, direction and will do the > rest > >> > >> of > >> > >> > driving. > >> > >> That is available as a ready made unit, 3 or 4 channels(motors) wide, > >> from xylotex, google for it. > >> > >> I have both a 3 axis and a 4, and within its limits (2.5 amps/motor) and > >> 30 volts max for the psu, it works quite well. It will need active > >> cooling, so > >> I made a box a few inches longer than the board, and the same square as > a > >> common psu fan, one in each end of the box, one blowing in and of course > >> the > >> other end is sucking the warm air out. That also works well. > >> > >> >-- Youda > >> > > >> >On Fri, Sep 4, 2009 at 12:21 PM, Peter C. Wallace <p...@mesanet.com> > >> > >> wrote: > >> >> On Fri, 4 Sep 2009, Youda He wrote: > >> >> > Date: Fri, 4 Sep 2009 11:42:21 -0700 > >> >> > From: Youda He <yo...@geometrysystems.com> > >> >> > Reply-To: "Enhanced Machine Controller (EMC)" > >> >> > <emc-users@lists.sourceforge.net> > >> >> > To: "Enhanced Machine Controller (EMC)" > >> >> > <emc-users@lists.sourceforge.net > >> >> > > >> >> > Subject: Re: [Emc-users] What hardware should buy to start > >> >> > > >> >> > Thanks, do we need to consider what CPU performance level is > needed, > >> >> > P4, Core2, GHz? memory size? > >> >> > > >> >> > -- Youda > >> >> > >> >> Probably 1 GHz or greater, 256M or more of RAM. If you are using > >> > >> software > >> > >> >> step > >> >> generation, for example with a parallel port driving the step motors, > >> > >> the > >> > >> >> main > >> >> issue will not be the processor speed, but be the latency of the PC. > >> > >> This > >> > >> >> may > >> >> require some fussing about with video cards, disabling SMI, or > >> >> choosing > >> > >> a > >> > >> >> different motherboard. The wiki lists some known good motherboards: > >> >> > >> >> http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Latency-Test > >> >> > >> >> Peter Wallace > >> > >> > ------------------------------------------------------------------------- > >> > >> >>----- Let Crystal Reports handle the reporting - Free Crystal Reports > >> > >> 2008 > >> > >> >> 30-Day trial. Simplify your report design, integration and deployment > >> >> - and focus on > >> >> what you do best, core application coding. Discover what's new with > >> >> Crystal Reports now. http://p.sf.net/sfu/bobj-july > >> >> _______________________________________________ > >> >> Emc-users mailing list > >> >> Emc-users@lists.sourceforge.net > >> >> https://lists.sourceforge.net/lists/listinfo/emc-users > >> > > >> > >------------------------------------------------------------------------ > >> >--- --- Let Crystal Reports handle the reporting - Free Crystal Reports > >> > 2008 30-Day trial. Simplify your report design, integration and > >> > deployment - and focus on what you do best, core application coding. > >> > Discover what's new with Crystal Reports now. > >> > http://p.sf.net/sfu/bobj-july > >> >_______________________________________________ > >> >Emc-users mailing list > >> >Emc-users@lists.sourceforge.net > >> >https://lists.sourceforge.net/lists/listinfo/emc-users > >> > >> -- > >> 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) > >> The NRA is offering FREE Associate memberships to anyone who wants them. > >> <https://www.nrahq.org/nrabonus/accept-membership.asp> > >> > >> Justice, n.: > >> A decision in your favor. > >> > >> > >> > ------------------------------------------------------------------------- > >>----- Let Crystal Reports handle the reporting - Free Crystal Reports > 2008 > >> 30-Day trial. Simplify your report design, integration and deployment - > >> and focus on > >> what you do best, core application coding. Discover what's new with > >> Crystal Reports now. http://p.sf.net/sfu/bobj-july > >> _______________________________________________ > >> Emc-users mailing list > >> Emc-users@lists.sourceforge.net > >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > > >--------------------------------------------------------------------------- > >--- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 > > 30-Day trial. Simplify your report design, integration and deployment - > > and focus on what you do best, core application coding. Discover what's > > new with Crystal Reports now. http://p.sf.net/sfu/bobj-july > >_______________________________________________ > >Emc-users mailing list > >Emc-users@lists.sourceforge.net > >https://lists.sourceforge.net/lists/listinfo/emc-users > > > -- > 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) > The NRA is offering FREE Associate memberships to anyone who wants them. > <https://www.nrahq.org/nrabonus/accept-membership.asp> > > Death is God's way of telling you not to be such a wise guy. > > > ------------------------------------------------------------------------------ > Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day > trial. Simplify your report design, integration and deployment - and focus > on > what you do best, core application coding. Discover what's new with > Crystal Reports now. http://p.sf.net/sfu/bobj-july > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. 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