Re: [CAD_CAM_EDM_DRO] Repeatability of Home switches

Nigel,
I have a quantity of new Omron slotted photo electric switches
available at a pretty reasonable price. I don't know if they are exactly
what you mean, but I'll try to take some photos, and e-mail them to you
later today.

Marv Frankel
Los Angeles

----- Original Message -----
From: "Nigel Bailey" <nigel.bailey@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Thursday, April 03, 2003 12:57 AM
Subject: RE: [CAD_CAM_EDM_DRO] Repeatability of Home switches


> I use hall switches with a tiny magnet on the moving part for sensing
> position, but in an environment which suffers from dust, which will
possibly
> block optical switches, However where there are ferrous bits floating
about
> in the air they will always get onto the magnet and cause repeatability
> problems.
>
> If ferrous dust is not a problem, it is possible to get ordinary hall
> switches pretty accurately repeatable by spreading the field from the back
> of the magnet with a wide pole piece of steel, and putting a narrow pole
> piece on the front of the magnet, making the front of the field "doughnut"
> more pointy and thus the field gradient steeper. (also a bit of metal
behind
> the hall sensor will tend to concentrate the field).
>
> I would be tempted to use a slotted opto switch for the job of home
sensing.
>
> BUT.... using either switch, remember to sense while moving only in one
> direction as the hysteresis of the switch will give a different position
for
> the transition off-on to the position of the transition on-off.
>
> Nig.
>
> -----Original Message-----
> From: mrgamber [mailto:mgamber@...]
> Sent: Thursday, April 03, 2003 2:46 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Repeatability of Home switches
>
>
> What repeatability should I expect from home switches?
>
> I can get a Honeywell Hall Effect VX series switch in a standard
> package that claims .005" repeatability. Can I do better with a
> typical hall effect switch?
>
> The output on the switch is confusing, does sink mean that it is
> coupling the supply voltage to the output? Or is it contact closure
> like a normal switch.
>
> link;
>
> content.honeywell.com/sensing/prodinfo/solidstate/catalog/c20048.pdf
>
>
>
>
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subjects, that are not allowed on the CCED list.
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