On Fri, 2009-04-03 at 21:23 +0100, Steve Blackmore wrote: > My lathe has a 100 slotted disc on the spindle, with one opto switch > fitted so far, the slot for that is longer than the others and gets me > one pulse per rev. It works fine to 3500 rpm as a rev counter. I want to > add two more opto's to get me an A and B channel to enable spindle > control for threading under EMC. Motor reverse is essential too. > > Are there any specifics as to the positioning of the opto's in relation > to each other? Do they need to be only a few slots apart, or more? I > think that the A & B need to be 1/2 slot out of sync - is that correct? > > Thanks > > Steve Blackmore
Just in case, I've seen some spindle disks using holes, the slots and fingers should be the same width so that you get a 50% duty cycle. A ___|^^^|___|^^^|___ B _|^^^|___|^^^|___|^ Another thing comes to mind, as an edge goes by the light has an analog transition that is "squared up" by the receiver at some on/off and off/on point. It seems that for DIY encoders you would want to be able to adjust that on and off trip point, so that you could get a 50% duty cycle. Although it may not really matter in practice. ------------- Kirk http://www.wallacecompany.com/machine_shop/ ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
