On Monday, June 04, 2012 02:01:32 AM Jon Elson did opine: > gene heskett wrote: > > On Sunday, June 03, 2012 03:06:54 PM dave did opine: > >> Any chance of collimating the LED's by putting a slit in front of > >> them? > > > > Placing the slit would be an exercise in precision I haven't mastered. > > I got a nearly lifetime supply of beam-break sensors out of scrapped > floppy drives. > The ones for track zero sensing had slits molded into the plastic and > would be > good for this. If you have any scrap floppy drives around you might > check for > suitable sensors. > > Jon
Well, after last nights playing with a new 50 cycle disk, I have a lashup that works. I put another 1k pot in series with each led, which allows me to get to 50% duty cycle required, and was able to get it working better in mode 0 than the 39 cycle disk worked in mode 1. But, I stand by my comments in last nights message about the encoder module. It is extremely sensitive to this bit of timing variation caused by a nominally 5 thou non concentricity in the way it is mounted (I believe because the center hole in the disk is slightly undersized, forcing one side of the hole to be pulled into the threads valley) both in duty cycle AND quadrature accuracy else the encoder.N.velocity output contains noise that at best is +- 50% of its average value despite the fact that even in the degraded state, it can still follow the spindle at 50 RPS! I think I can improve it further yet with some mechanical adjustments that include marking its high point, and polishing out the central hole 3 or 4 thou on that side, then adding a layer or 2 of alu foil between it and the bearing nut to shim some of the about 10 thou wobble out of it. Once that has been accurately done, I don't think the z drive will have nearly so ragged a drive tone in the G76 cycle. But even noisy, the 39 cycle disk cut some 28 tpi threads that were an excellent fit on a #209 nipple for one of my BP rifles. Sharpening the single tooth tool properly is quite an exercise though. 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> Cats, no less liquid than their shadows, offer no angles to the wind. ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
