On Friday 23 November 2012 09:14:56 andy pugh did opine: > On 23 November 2012 04:04, Gene Heskett <[email protected]> wrote: > >> To buy the crank code-wheel new is not that cheap ($100) but there > >> ought to be many in the junkyards now. The correct pickups are less > >> likely to exist, but those are $17. > > > > Since the requirement is that its ferrous, I seen no reason that can't > > be a milling machine project. > > The target wheels we have on our engines are _not_ ferrous. They are a > magnetic track and the crank sensor has no internal magnet. > (I can't find that actual sensor on the Allegro site).
For a hall sensor to work, there must be a magnetic field for it to sense. Generally that requires a ferrous material. It can be magnetized, or a bias magnet in the sensor can make a soft iron toothed wheel work. Not all steels are magnetic though, as you can check by trying to pick up with a magnet, an exhaust valve from one of the engines Ford has been making since 1955. :) Its 'austenitic'(sp). You would have to warm that valve back up to near melting, and let it cool slowly in order for it to regain its magnetic properties as it cools below its 'curie' point temperature. > Having said that, ebay has many "trigger wheel"s at quite low prices > which could work, though most seem to be quite low-resolution. > http://www.ebay.com/itm/261124381577 > > You can see the one I have in my drawer at the bottom of this picture > here: > http://images.sklepy24.pl/87078282/3668/large/kolo-pasowe-walu-korboweg > o-1-8-tdci-dayco.jpg You can just about make out the magnetic track. > (There are two parts there, 6B319A and 6B319B) 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> is up! No foreign coins. ------------------------------------------------------------------------------ Monitor your physical, virtual and cloud infrastructure from a single web console. Get in-depth insight into apps, servers, databases, vmware, SAP, cloud infrastructure, etc. Download 30-day Free Trial. Pricing starts from $795 for 25 servers or applications! http://p.sf.net/sfu/zoho_dev2dev_nov _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
