Re: [CAD_CAM_EDM_DRO] Re: Gecko G420's question

Dave,

Do Know the model number of the Gettys motor you have? Please Post it. I
have a good friend that is a Getty's rep. in Detroit. I'll see if he can get
the data for you.

----- Original Message -----
From: "David Eldredge" <techdave@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, April 30, 2002 6:25 AM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Gecko G420's question


> Thank you Eric, for your informative response. I expect when the drives
> actually come out there will be more information available on its
> "commutation scheme." I have some brushless servo motors but they have
> pancake synchro resolvers mounted on them. Motors are made by Getty's,
and
> I ran into a dead end trying to get info from the new owners of that
> company.
>
> Thanks again, Eric.
>
> Tom Eldredge
> ----- Original Message -----
> From: "Unterhausen Umberto" <unterhausen@...>
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Sent: Monday, April 29, 2002 9:29 PM
> Subject: [CAD_CAM_EDM_DRO] Re: Gecko G420's question
>
>
> > David Eldredge writes:
> >
> > "Gentlemen," -- loosely speaking in my case
> >
> > "Does anyone know what type of feedback the G420's are
> > expected to use?
> > Hall effect or encoder?"
> >
> > As I recall, they are Hall with encoder. In my
> > collection of drives and motors there are: Halls,
> > Halls with encoders, Halls with encoders with some
> > kinda absolute track, encoders with simulated halls,
> > and resolvers.
> >
> > When you use Halls with encoders, there are two
> > approaches. The first is to commutate the motor as if
> > you just had the hall signal and use the encoder to
> > keep track of your error. In this sense, the drive
> > doesn't know if the Hall is about to signal to go to
> > the next phase or not, it just does the commutation
> > with the feedback. My guess is that this is how the
> > Geckos will be. Other drives require that they know
> > the encoder counts and then use sinusoidal
> > commutation. I like to think of a brushless motor as
> > a stepper motor with a very small number of steps per
> > rev, even though Mariss says it's not true. You can
> > get them to step, but you will hate yourself in the
> > morning. The way I look at it a stepper motor
> > requires commutation, a dc motor does it thru
> > mechanical means.
> >
> > "Will the G420s save money on servo motor cost? I
> > understand the
> > benefits of eliminating brushes and commutators, but
> > are there many sources
> > of motors for them? "
> >
> > Brushless took over the machine tool and robotics
> > market sometime in the mid-1990's and thus they are
> > the wave of the future. Ebay has a regular supply of
> > brushless motors. I would say that high quality
> > brushless motors are more numerous on ebay than high
> > quality dc motors, but I don't really look that hard
> > for the DC motors. New brushless motors cost at least
> > $500, but all the other options are also
> > breathtakingly expensive if you buy them new retail.
> >
> > I skip the question about making them.
> >
> >
> > "How about some more discussion on what this new
> > development will bring
> > to the hobbiest CNC guy."
> >
> > The Gecko drives make brushless motors available to a
> > person that just wants to go out and buy a drive. The
> > competition costs $500 - $1000. The motors rarely go
> > for more than $100 on ebay, and almost never go for
> > more than $200. Obviously, it's still high end, and
> > it is considerably more involved subject than DC
> > motors or steppers.
> >
> >
> > Eric
> >
> >
> >
> >
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> http://www.metalworking.com/news_servers.html
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> http://groups.yahoo.com/group/jobshophomeshop I consider this as a
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