>I'd expect the lab-built "digital motor" approach to be less
>than the cost of a roughly equivalent stepper
>solution as viewed by total system cost.
A new shaft encoder can be had for $19.00 these days. Adding
a "second shaft" to any surplus DC motor is a piece of cake if you
have access to and know how to use a mini-lathe...Or buy a surplus
motor with encoder. H-bridge ICs are around $5.00, microcontroller
around $3.00...Here's what's missing....Good PID code for the
micros....Right now it's under lock and key but will soon trickle
into the public domain.
--- In Homebrew_PCBs@yahoogroups.com, uhmgawa <uhmgawa@m...> wrote:
> Phil wrote:
> > --- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
> > <stefan_trethan@g...> wrote:
> > ...
> >
> >>DC servos are not the answer to a simple drilling machine for
sure,
> >
> > as the
> >
> >>controllers are unnecessary complicated.
> >>But we all have our opinions.
> >
> >
> > While I'm reluctant to recommend servos for cost reasons, I think
they
> > can be done at about the same complexity level provided one is
> > conversant with microcontroller design and programming. They are
more
> > reliable as open loop steppers can miss steps in some
circumstances
> > and the encoder always tells you where you are.
>
> Agreed. I was assuming we are talking about
> "midnight engineering" here rather than looking
> for a $ervo motor off the shelf. I'd expect the
> lab-built "digital motor" approach to be less
> than the cost of a roughly equivalent stepper
> solution as viewed by total system cost.
>
> --
> uhmgawa@m... www.gnu.org