Re: home switches

And what's really interesting is that when you open the fancy box and
see the o-ringed roller acting on a "standard" microswitch...

I've said before that what you want to do is to be sure and TALK with
an app engineer at the switch company-ies.

Show an interest in what he or she has spent an adult life getting
good at, and come away knowing that switches can be made from good to
bad, and not all the good ones are expensive; nor are all the bad
ones cheap!

And further, that "food" and "bad" for home switch is not necessarily
the same as good and bad in other uses...

At a minimum, request the specs and READ 'em...

Ballendo

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Ed Gilbert" <co2man@n...>
wrote:

> Hi,
>
> Ballendo is absolutely correct as to accuracy.
> The SS Plunger type with a roller on top are rated at .01mm

repeatability.

>
> These are standard brands Square D, Allen Bradley, etc.

Automationdirect.com

> brand labels the Telemechanic brand and sells them for $34.00 US

each. Check

> out the ABM models.
>
>
> Best,
>
> Ed Gilbert
>
> Gilbert Engineered Systems
> 632 Warrenton-Embro Road
> Macon, NC 27551
> 252-257-0539
>
> > -----Original Message-----
> > From: ballendo [mailto:ballendo@y...]
> > Sent: Tuesday, March 23, 2004 9:54 PM
> > To: CAD_CAM_EDM_DRO@yahoogroups.com
> > Subject: [CAD_CAM_EDM_DRO] Re: home switches
> >
> > Hello,
> >
> > If you do a search of the archive for home switch, you'll find
> > perhaps a hundred posts... (25 by me<G>)
> >
> > The short answer is: Microswitches of the proper type--and even

some

> > relative cheapies-- are far more repeatable than is often

imagined.

> >
> > Second, if you AND a single slot index wheel with your

microswitch,

> > and use an optointerrupter for reading the index wheel slot, you

can

> > get even better repeatability. This is the standard technique

used in

> > commercial cnc machines; where they just use the existing servo
> > encoder's index pulse AND'd with a mechanical switch.
> >
> > Hope this helps,
> >
> > Ballendo
> >
> > P.S. Try the microswitch by itself first. Less work, and you may

be

> > quite surprised. Putting the surprise odds in your favor is a good
> > homing routine. Slam into the NC switch, reverse, slow WAY down,

and

> > move OFF the switch to find home. Since you're moving at a slow

rate,

> > and that rate is the same each time, repeatability is pretty

decent.

> > You are also in a state that a wrong move will RE-trigger the

switch.

> > An important consideration often left out...
> >
> > If you choose an oiltight submini simulated roller, it is low cost
> > and can handle at leat some of the rigors of the machining
> > environment. Certainly okay for your micromill, IMO.
> >
> >
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "david_margrave"
> > <david_margrave@y...> wrote:
> > >
> > > Hi
> > >
> > > I'm a bit confused about the whole concept of home switches.

How do

> > > you get any degree of accuracy and repeatablity based on

mechanical

> > > contact of a switch closing? What sort of things have people

done

> > > for this? Just wondering because I'm at the stage in my micro

mill

> > > CNC project where all I have remaining is wiring up the
> > > home/limit/stop switches. The stop switch was easy - just

connected

> > > the switch to the output-enable pins of the allegro-micro 5804
> > (maybe
> > > some pull-up resistors were used to, I forget exactly). I am

using

> > > EMC on linux.
> > >
> > > cnc project page http://www.margrave.com/static/cnc/
> > >
> > > Dave
> >
> >
> >
> >
> > Addresses:
> > FAQ: http://www.ktmarketing.com/faq.html
> > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> > Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
> >
> > Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> > Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> > List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com,

wanliker@a...,

> > timg@k...
> > Moderator: pentam@c... indigo_red@q... davemucha@j...
> > [Moderators]
> > URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> >
> > OFF Topic POSTS: General Machining
> > If you wish to post on unlimited OT subjects goto:
> > aol://5863:126/rec.crafts.metalworking or go thru Google.com to

reach it

> > if you have trouble.
> > http://www.metalworking.com/news_servers.html
> >
> > http://groups.yahoo.com/group/jobshophomeshop I consider this

to be a

> > sister site to the CCED group, as many of the same members are

there, for

> > OT subjects, that are not allowed on the CCED list.
> >
> > NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY

POSTING THEM.

> > DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> > bill
> > List Mom
> > List Owner
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
>
>
>
> -------------------------------------
> This message has been scanned for viruses and
> dangerous content by NCOL.NET, and is believed to be clean.