Re: rough circle

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

>
> Hi all,
> got a 3 axis servo driven gantry, rutex + deskcnc, it's working
> ok,but when doing full or half circles using the cam generated toolpath
> the finish is not good at all, if I slow down the feedrate to about
> 1000mm/m it gets better but still not good enough.
> I'm wondering if deskcnc does not have the necessary speed when using
> two axis the same time or it's the servodrive is not fast enough to to
> correct the possition.
> It's not facets, it's more like the tool gouges in as if I was using
> a dull endmill.
> It has a 2.5 lead leadscrew 500 ticks encoder, and x4 multiplier on
> servo drive.
> so, it's a 0.005mm per step with a max speed set at 3800mm/min.
> that's = 200 steps per mm.
>
> Any sugestions.

Do you get that great finish on straight cuts on both X and Y ?
Do you also get a great finish on an angular cut, where both X and Y
are moving ?

I'm not familair with DeskNC, does it have look ahead programming ?

Wjhat I suspect is that the machine has vibration so it cannot cut a
smooth finish, or that the arc is being cut in segments and at the end
of each line, it pauses. at each pause, the cutter idles and cuts a
little larger spot.

Maybe if you made a semi-circle of only 16 points, you could see it
each line end has athe same effect. then try 32 points and keep
increaseing the number to see where it starts.

Also, have you tried a G code to cut a circle ?

Dave