Re: rough circle

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Fred Smith" <imserv@v...>
wrote:

>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "afogassa" <afogassa@y...>
> wrote:
>
> > thank's Fred,
> > If it can do all axis at the same time why there is no provision
> for
> > helical milling ? or interpolating three axis.
> > here is what happens, I'm using powermill to generate the

gcodes

> > from 3d surfaces to machine a stearing wheel mold, finish looks

good

> > at the outside radius, but at the center ofthe stearing wheel

there

> > is smaller radius curves where I'm having problems with finish.
> > the code generated is all line segments not arcs and I have the
> same
> > resolution for x y z .
>
> Helical milling has very limited usage on hobby and desktop

machines.

> Thread milling, a fairly common use, can easily be done with 3 axis
> interpolation and most any decent 3D cad-cam system.
>
> DeskCNC is superb at simultaneous 3 or 4 axis interpolation,

provided

> you don't exceed the 300 blocks per second throughput limit.
>
> If you examine your Powermill program, you will probably find that

you

> have interpolated the surfaces at an accuracy tolerance more fine

than

> necessary, and probably at a much higher resolution than your home-
> built machine can actually cut. Simply set the interpolation at a
> more reasonable level and regenerate your CNC program.
>
> It may be that you need to apply a different cutting strategy to

the

> inner radius than the outer. A uniform cutting pattern may be

causing

> too high a block density near the center, compared to the distance
> traveled.
>
> Hopefully this will help you solve your problems.
>
> Fred Smith - IMService
> http://www.cadcamcadcam.com/hobby
>

I think you're right, maybe there is more line segments on the
smaller radius than deskcnc can handle with a 300 blocks CC.
That's why it gets better when I slow down the feed rate.
I'll see if I can change the line segments resolution on the code.