On Friday 22 July 2016 19:57:38 Jon Elson wrote: > On 07/22/2016 03:54 PM, Gene Heskett wrote: > > Thats one of the reasons I thought the 627 was the better device. > > Then I recalled that the index pulse resets the encoder counter, and > > it seems to me that the unit used for an index pulse would have its > > stuff all in one sock by the second time that ferrous flag came by, > > and that would then cancel the half a tooth error since the encoder, > > when in ABZ mode is counting edges. > > > > Am I wrong? In which case what device to use? > > The 667 detects the passing of the gear tooth, so it is rather > insensitive to small magnetic variations and the distance between > sensor and gear. A sensor that is affected by the space between gear > and tooth would give a different pulse width depending on spacing. > The 667 gives a very good 50% duty cycle largely unaffected by > spacing. In the Bridgeport hack, I had a VERY small clearance around > the bull gear to place the sensor, and no room to adjust the spacing. > If you have the room, a proximity sensor could be fine, but then you'd > have TWO interacting adjustments to deal with - sensor distance to > gear, and sensor quadrature spacing. I hate having to adjust stuff > where you have to position something to set TWO different parameters > at the same time. > > Jon
Yup, that turns me into a bear with 4 sore paws. Right now, gimp is doing that for me. The doc version in the repo's is about 15 to 20 releases older than the code, and no one on the gimp-user list knows a thing more that I do. But the way I read both this, and the 627 docs, they both powerup at a logic high, and they both have the AGC so the spacing is non-critical, but the 627 doc would appear to claim a wee bit better 50/50 performance, with identical rise and fall times where the 667 isn't symmetrical in that regard. Both can go to 20 kilohertz or to 12k rpms on their sample target disk if I read that right. Thats a BIG IF atm though. What I had the vision of for mounting 2 of them was to measure that gears OD, the cut an arc 50 thou bigger in some 1/2 alu plate IP have, then sink 2 of the 627's into carved pockets, one of which was wide enough to allow a quadrature adjustment to be made. Possibly with a third one positioned to read the head of a 3mm cap screw planted in the rim of the gear, below the bottom line of the teeth for use as an index pulse. If I can drill and tap that gear as I get the impression from the lack of wear, that its made out of some pretty hard stuff. Depends of there being room for the screw head to clear everything. The lid is on the spindle housing so it will need to come off to make that judgement, and to mark a tooth for counting teeth reasons. Might have to clean it up and epoxy or superglue something inside the gears rim. Maybe even use locktights GO2 si glue. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic patterns at an interface-level. Reveals which users, apps, and protocols are consuming the most bandwidth. Provides multi-vendor support for NetFlow, J-Flow, sFlow and other flows. Make informed decisions using capacity planning reports.http://sdm.link/zohodev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
