Re: [CAD_CAM_EDM_DRO] Re: typical servo speeds

The ones I have opened up look just like the big ones shrunk down a bit .
I never throw a hard drive away without taking out the very powerful
magnet that is inside.

--
Ron Kline

American Precision Ceramics .. (Industrial ceramics)
Central Ky.



optics22000 wrote:

>
> Graham,
> You might try hacking apart a hard drive, they have very fast moving
> coil drives that move through an angle of about 45°. It is easy to
> remove the case to get at the mechanism. The small drives of course
> have very small drive mechanisms.
>
> Companies like http://www.h2wtech.com/noncommdcactu.htm
> <http://www.h2wtech.com/noncommdcactu.htm> make small
> voil coil actuators and related equipment, which could be pretty fast.
>
> Hard drive head position feedback is usually through tracks on the
> disk, so you'll need to come up with your own. The simplest thing is
> probably a LED, a shutter in the moving part, and a silicon
> photodetector. The shutter is arranged so that a one end of travel
> no light is blocked, at the other end all light is blocked, half way
> half the light is block. A silicon photodiode can be found in
> several devices, for example a CD player or try digikey.
>
> If you manage to make one of these fly, we'd love to see it!
>
> It is probable that a voice coil drive like the hard drive motor will
> not have as high an energy density as an optimized motor with
> commutation.
>
> Has anyone on the list opened up a really small hard drive? I've
> never had my hands on one that could be dissected.
>
> regards-
> Elliot
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com
> <mailto:CAD_CAM_EDM_DRO%40yahoogroups.com>, "Graham
> Stabler" <grezmos@...> wrote:
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com
> <mailto:CAD_CAM_EDM_DRO%40yahoogroups.com>, Jon Elson <elson@> wrote:
> >
> > That is encouraging Jon.
> >
> > > A real hummingbird, I believe, flaps its wings at about 600 Hz
> > > (or am I thinking about a bumblebee?)
> >
> >
> > A Bumblebee (I'm currently analyzing microCTscans of a honeybee)
> flaps
> > at around 200hz, a humming bird depending on the species is in the
> > 15-30hz range though I'd have to look it up to be sure. I'm looking
> > at building something inspired by an insects flight apparatus but
> more
> > on the size scale of a humming bird. This rig is to allow PIV and
> > such analysis in air (other rigs have been scaled up and done in
> oil).
> > Its a tall order as the wings describe a figure of 8 and they have
> > controllable stroke reversal for control all at 20hz, the reversals
> of
> > course are at 40hz!
> >
> > Small flies can go right up to 1000hz
> >
> > All of the insects are resonant mechanisms meaning that the inertia
> is
> > accounted for with elastic storage, the muscles need only do useful
> > work and overcome losses. They can even tweak the resonance by
> > stiffening the thorax, its neat stuff.
> >
> > Graham
> >
>
>