On Monday 12 October 2009, Hubert Bahr wrote: >I am actually working on two machines in parallel. An X2 and an X3. >The X2 already has LMS addon pulley set for spindle power. For it I am >thinking of just Drilling single hole on one side of the larger pulley >and sensing that as a index pulse and starting along the lines suggested >here >http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Closed_Loop_Spindle_Speed_Contr >ol Tapping may not be desired on this machine. > >For the X3 I am planning to build a belt drive mod for the machine that >will give me three speed ranges, I am looking at cutting interrupter >notches into one edge of the spindle pulley or at least attaching a disk >containing the notches. The quadrature encoder/sensors I am familiar >with were designed to be attached to a servo shaft, not a tool holding >spindle. I am guessing if I provide slots of uniform presence and >absence of material around the periphery of a disk this will give my the >50% duty cycle. Then if I set two detectors in a relationship where one >is offset from the other half a slot away this provides a method of >detecting 4 transitions per slot instead of just two. And then the >relationship of the highs and lows determines direction. A third >detector senses a single slot/hole elsewhere that rotates in a constant >relationship with the other slots.
That is the general idea, and there is code to cut such a wheel on the wiki, or the modified version of that code I posted yesterday will cut a smaller version with fewer holes. Compare them to see where I modified the wiki's code to do my smaller one for my 7x12. I also posted a pix of it 10 minutes ago, but no idea if the server can take pictures that big. >I think I am approaching the limits >of the number of pins available from a parallel port for a 4 Axis mill. >The number of slots to use is a trade off between desired/necessary >resolution. What resolution is required for tapping? Isn't the >starting edge of an index pulse sufficient, or do they need to track >loading on the spindle? Loading needs to be tracked in real time. [snip] -- 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> Sailing is fun, but scrubbing the decks is aardvark. -- Heard on Noahs' ark ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
