On 06/14/2011 08:53 AM, Kirk Wallace wrote: > On Mon, 2011-06-13 at 13:47 -0700, Peter Loron wrote: >> Hello, folks. Can anybody comment on using hall effect switches on a 3 >> axis mill for limit / home switches? Seems like they would have some >> possible advantages over physical contact switches. >> >> Thanks. >> >> -Pete > My Hardinge lathe uses Hall limit and home sensors. The Z axis target > magnet is small and mounted such that there is minor protection from > chips. There is a small gap between the magnet and sensors when aligned. > If chips are in the magnet area, they get wiped off, but not too small > such that small chips don't bind in the gap. the magnets are weak enough > to have largesh chips fall off. The trip location accuracy only needs to > be within about 2 or 3mm because, in my case, the home sensor is used in > conjunction with the screw encoder index, which should be accurate > to .002mm or better. What I like about Hall sensors is that they are > machining fluid proof and will practically never wear out or change the > trip point or behavior over time. I tend to think using mechanical > micro-switches is silly, but a lot people use them to good effect. The > Hardinge Z axis uses a Hall sensor with magnet in a micro-switch > housing: > http://sensing.honeywell.com/index.cfm?ci_id=154286&la_id=1&Ne=7&sid=1308EB555700&ci_id=154286&N=3591+4294966517&la_id=1 > Short URL: http://alturl.com/v2jzu > > These are mounted in a location well protected from chips, but the area > is not sealed from coolant, which is fine because the sensors don't mind > fluids. > > The Z sensors are in an aluminum threaded barrel similar to this one: > http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=480-3256-ND > Short URL: http://alturl.com/netsd > > They tend to be expensive, but it should not be too difficult to machine > a barrel and pot an IC sensor with leads into it
Yeah, I'm going to roll my own...I have a pile of Allegro sensors here. Also, retail on the Honeywell sensors is probably more that I've got invested into the whole mill... :-) -Pete ------------------------------------------------------------------------------ EditLive Enterprise is the world's most technically advanced content authoring tool. Experience the power of Track Changes, Inline Image Editing and ensure content is compliant with Accessibility Checking. http://p.sf.net/sfu/ephox-dev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
