Re: [CAD_CAM_EDM_DRO] brushless vs. brushed servo motors

Since they don't rely on any kind of mechanical contacts, they have lower
maintainance and such forth. They get used a lot if there's a risk of
explosive gases in their enviroment, as they don't generate sparks, in
vacuums, where it's easier to implement them without degassing problems, and
in clean rooms, where the dust generated by the contacts in brushed motors
can't be tolerated.

No mechanical contacts also means better mechanical performance. I read that
one of their main problems is that they can get very warm and sometimes have
problems conducting the heat away quickly enough, so a lot of them seem to
have cases specifically designed for excellent convection cooling
properties - like big heatsinks.

They usually have very high strength rare earth magnets in them, giving them
very high power densities - small motors that produce a lot of torque for
their size. Which is important if you have the drivers for one axis mounted
on another, since one will have to carry the other's mass, effectively. This
is important for things like spindles, because they're usually very high
power motors.

Almost all new commercial machines aim towards brushless motors, but newer
controllers are allowing the brushed motors to keep up for a while longer.

Hobbyists look set to start inheriting some newer technologies within the
next decade or two. Numerous new motor formats are being made realistically
available to industry, which means that the older technology, high tech to
us, will be being discarded and we will no longer have to compete with a
commercial buyer for things like brushed servos. Something that is already
happening right now.

Steppers will become the ultra-poor guy's option = me! :^)

I would expect brushless servos to start getting much cheaper soon. They are
entering a widespread use phase, and soon, linear motors will start hitting
the scene big time. Linear motors will start forcing brushless motors our
way, as it gets harder and harder to find machine tool manufacturers who'll
want to buy them rather than the newer linear motors.

Soon, every hobbyist will be able to afford a brushless powered knee mill at
home. Happily optimisitc, but certainly close to reality.

Kind regards,
John

----- Original Message -----
From: "a57chevytruckguy" <a57chevytruckguy@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Wednesday, November 17, 2004 2:46 AM
Subject: [CAD_CAM_EDM_DRO] brushless vs. brushed servo motors


>
>
> I am trying to put an old boss back together everything was taken off
> (except the ball screws) so I am staring from scratch and I have been
> seeing brushless servo motors on ebay cheap......I was woundering what
> (besides the the fact 1 has brushes and 1 doesnt) is the differences
> are? Can I use regular controlers?
>
> Thanks eveybody!
>
> Jon
>
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