Re: Why is the push to such high step rates (Grex and Arc100)?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "lcdpublishing"
<lcdpublishing@...> wrote:

>
> Hi Graham,
>
> Have you found any linear motors and drivers? I too am facinated by
> them and would like to tinker with something using them at some point
> in time. THe only stuff I have found so far is the high-end industrial
> stuff of which I cannot afford.
>
> Chris
>

The drives from Copley motion are within the realms of possibility for
the serious amateur. They consist of a stainless tube containing
magnets and a stator/rotor(not sure) containing the coils that moves
back and forth on bearing supplied by the user. I built an ultrasonic
scanning system using them for my old job, that used renishaw encoders
but most people don't want micron resolution. You could use them with
the US digital encoders I'm sure (might require some differential line
drivers or something). If you look at there stuff then for the sake
of cost you would probably just want to get the bare tube and motor
units like I did rather than the actuators.

They do several drives that can be set up with RS232 and controlled
with Canbus however they can also be set up for step and direction
control though I never tried.

I recently bought a THK branded demo unit which contains a full copley
motion actuator and renishaw encoder along with driver. When I get
the chance I'll get it up and running to check it out.

Fanuc actually do a 3D single point shaping machine that is used to
make optical components, I think this uses a linear motor of this or
similar type to get the rapid sanning action of the diamond cutting tip.

Graham

p.s. The fast laser system you saw was probably a dual galvo system,
this is something that I have not seen hobbiests try but for vector
cutting rather than scanning/marking normal servos and a g-rex would
probably work.