Re: DRO: USDigital new resolutions 250cpi x 4

Russell,

There are a lot of machines out there based on 5TPI (.200"lead)
screws. When driven by a "typical" 1.8° stepper, which has either 200
(fullstep) or 400(halfstep) SPR(Steps Per Revolution), you get a
SYSTEM resolution of .001 or .0005 inches/step.

Another factor is that you generally want a resolution at least
double your intended accuracy; so for a machine designed to make
parts of .001 tolerance, the scales of .0005 are a minimum.

Now to your router: There are many commercial (and expensive) routers
which have only 500 SPI (Steps Per Inch). This is often a trade-off
to get the higher top speed this type of machine needs. Modern
technology is making some of these trade-offs less demanding than
they used to be, due to things like fast block times and pulse trains
from the controllers, affordable microstepping drives, and more
powerful magnets, which translate into more compact and electrically
efficient motors...

Beware of "empty" resolution. This is where your machine makes
several steps without moving. Also beware of equating resolution with
accuracy; they are NOT the same thing!

Hope this helps.

Ballendo

--- In CAD_CAM_EDM_DRO@y..., Russell Shaw <rjshaw@i...> wrote:
> Why does anyone need that resolution? Wouldn't backlash
> be greater? and isn't 1/500=0.002? I'm figuring out what
> resolution to put into the router i'll make.
>
> Dan Mauch wrote:
> >
> > Yes but they were suppose to also come out with a 500CPI or .0005
which
> > is what everybody really needs. That was last april.
> > Dan
> >