Re: [CAD_CAM_EDM_DRO] Does a VFD do the trick?

my experience is with nema 23 size steppers.
they do not offer much resistance when power is off.
and there is no way they can harm my drivers- they can
not generate any voltage worse than what happens when
they are stepped by the controller - and that's all
snubbed for protection anyway.
they certainly can't generate significant current
unless i put an electric drill on the crank to spin em
up.
desktop machines i know almost always have hand
cranks on the steppers. straight from the factory they
come this way.
i don't really understand any way they could hurt by
hand cranking them.
if i'm the slightest bit wrong, please, somebody,
flame my ass bigtime and fast!


--- Familia Peter Arce & TAD <peteryco@...>
wrote:

>
> The 2 motors are inside the machine linked with belt
> or gear.
> But when I have a stepper I still have a force to
> overcome cranking it
> when the current is switched of. And as I understand
> if I crank a
> switched off stepper it generates current that might
> kill the driver
> (lets say a Gecko).
> Right?
> Sven Peter
> ----- Mensaje Original -----
> De: juan gelt <juangelt@...>
> Fecha: Viernes, Enero 6, 2006 9:15 am
> Asunto: Re: [CAD_CAM_EDM_DRO] Does a VFD do the
> trick?
>
> > you might reconsider steppers as they are cheap to
> > control.
> > you can get steppers with double shaft and put
> crank
> > on it. my cnc mill is like that. no trouble to
> work it
> > manually at all.
> >
> > --- Familia Peter Arce & TAD
> <peteryco@...>
> > wrote:
> >
> > >
> > > Hello friends,
> > > I fell over my own words yesterday and have to
> make
> > > the best out of it.
> > >
> > > A (2,5-3tons) beauty of surface grinder from
> 1957 I
> > > have to get again to
> > > work. Complete new electrics with a PLC.
> > > What I thought were reduction motors are plain
> three
> > > fase motors (1700
> > > revs, 125W) inside 1 to 1 geared.
> > > Out side reduction Y 1:3 makes 1,7mm per motor
> turn
> > > and Z 1:7,5 makes 0,13mm per motor turn.
> > > With solid state relays I will get the Y
> movement
> > > reasonable well to work.
> > > But for the Z movement not. I would like to have
> an
> > > automatic down feed
> > > graduable from 0,001 to 0,04mm until I am close
> to
> > > the final measurement
> > > and still be able to manage the machine by hand.
>
> > > That makes me exclude steppers as option.
> > >
> > > Does a VFD on standard three fase motors do the
> > > trick that I can turn it
> > > just something like 2 degree or more per impuls
> and
> > > later leave it free
> > > spinning?
> > >
> > > As you know me, I work on all kind of machines,
> but
> > > I hadn´t to convert
> > > any with this kind of task and have no hands on
> > > experience with VFD's.
> > > The PLC has encoder inputs so if necesary I can
> hook
> > > some on the motors,
> > > screw or nut.
> > >
> > > The owner first of all needs the machine
> running,
> > > keeping future options
> > > open, but a automatic use and position feed back
> > > will be greatly
> > > apreciated. And tiny VFD's aren´t that much out
> of
> > > financial reach.
> > >
> > > Who has played with VFD's and standard threefase
> > > motors (240V Delta
> > > generated with slave motor) and can give me a
> > > reference if it is feasonable?
> > >
> > > Best regards from Costa Rica, where clocks work
> > > diferent.
> > >
> > > Sven Peter
> > >
> > >
> > >
> > > 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@..., timg@...
> > > Moderator: pentam@...
> indigo_red@...
> > > davemucha@... [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
> > >
> > >
> > > CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> > >
> > >
> > >
> > >
> > >
> >
> >
> >
> >
> > __________________________________________
> > Yahoo! DSL ? Something to write home about.
> > Just $16.99/mo. or less.
> > dsl.yahoo.com
> >
> >
> >
> > 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@..., timg@...
> > Moderator: pentam@...
> indigo_red@...
> > davemucha@... [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
>

=== message truncated ===




__________________________________________
Yahoo! DSL – Something to write home about.
Just $16.99/mo. or less.
dsl.yahoo.com