On Thursday, February 16, 2012 01:40:53 PM Erik Friesen did opine: > What I have in mind is my own "daughtercard". Encoders would be fed > through to the 5i25. I would use a mcp3208 in spi mode to give me 8 > analog inputs, assuming the 5i25 can do it. > > I have been looking at the gecko drives, they are 10x microstepping, > which seems overkill. They do have some decent features though. > However, my computer can only do 15khz software step generation, which > doesn't do well with 10x microstepping and speed. > The main advantage to the microstepping is two fold, and both come from the same effect, that of smoothing the steps and getting a lower excitation amplitude of the resonances in the motors mechanical vs magnetic characteristics. Remember, you are dealing with a very strong magnet whose instant position is determined by 2 very strong magnetic fields, so the armature is effectively held in position by 2 springs of varying strengths according to the currents programmed for that particular position in the full step envelope
You will need less in the way of dampers to control this resonance, and at the same time the motors turn noticeably quieter. At one point 3 or 4 years back I got curious and set the xylotex's for 1/2 step, and you could hear the motors howling in the neighbors back yard, so that experiment was terminated the same day. When I bought the MM542 drivers I'm using now I knew the /64 microstepping they could do was not feasible, not on an atom powered D525MW board, but that /16 might be usable & if that was pushing the computer I could always go back to /8 which I was using with the xylotex drivers. The noise reduction was noticeable, there are now some speeds less than 1 rps, where the motors are almost dead silent compared to the other noises from the fans and such, and its a bit odd to see them doing half a rev per second silently. I have not checked to see how far I can push the rapids as I had a previous config setup that ran much faster, but that was also at the expense of long accel times, but there was no real gain in job times so I have not explored the rapids ranges above nominally 16 ipm on my toy yet, better things to do & too cold in the shop to spend days fine tuning that sort of thing. > On Thu, Feb 16, 2012 at 8:55 AM, Andy Pugh <bodge...@gmail.com> wrote: > > On 16 Feb 2012, at 14:29, Erik Friesen <e...@aercon.net> wrote: > > > How feasible is it to use the mesa 5i25 in a similar way to the > > > universal stepper controller? IE.. Use hardware step generation + > > > encoder > > > > feedback? > > > > Just a bare 5i25, or using daughter cards? > > You ought to be able to do it with a 7i76 and a 7i77 (that's the > > stepper board _and_ the servo board at the same time. Otherwise you > > would need a special firmware I think. 25 pins might be a bit few, > > though there is a second 25 pin header too. The dedicated daughter > > boards use > > serial-connected hardware for the extra IO pins with only the > > stepgens, encoders and pwms wired direct back to the 5i25. > > > > ---------------------------------------------------------------------- > > -------- Virtualization & Cloud Management Using Capacity Planning > > Cloud computing makes use of virtualization - but cloud computing > > also focuses on allowing computing to be delivered as a service. > > http://www.accelacomm.com/jaw/sfnl/114/51521223/ > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------ > ------ Virtualization & Cloud Management Using Capacity Planning > Cloud computing makes use of virtualization - but cloud computing > also focuses on allowing computing to be delivered as a service. > http://www.accelacomm.com/jaw/sfnl/114/51521223/ > _______________________________________________ > 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) My web page: <http://coyoteden.dyndns-free.com:85/gene> The finest eloquence is that which gets things done. ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
