Contouring and CVV was Re: DeskNC for Windows experience anyone?

--- In CAD_CAM_EDM_DRO@y..., "ballendo" <ballendo@y...> wrote:

> Chris,
>
> I don't know if the MillmasterPro/windows has contouring or not. As

I

> said, I have not used it. But the advertising I did see, mentioned
> improvement of several items which I am aware were problems with
> their DOS product.
>
> Flashcut has had contouring, but by whose definition? And other PC-
> based cnc controls also beg this question.
>

>
> The earliest solution was to begin the next moves' accel at the same
> point that the current moves' decel began. This is still the most
> common form of "contouring" in commercial cnc machines. The down

side

> is, the "corners" are rounded when using this approach. (corners may
> also be rounded by servo following errors) Inaccuracies from both
> following error and the accel/decel contouring algorithm increase
> with higher feedrates and also with increased toolpath angle change
> between blocks.
>
> True contouring(CVV) requires trajectory planning,
> We have now come to the place/time in our computer capabilities that
> this can be done "real-time", allowing feedrates to be changed

on-the-

> fly, while still maintaining the most CVV possible, given the limits
> of the physics acting on the machine. Expensive controls (and
> Master5) do "real" trajectory planning. I'm not sure where EMC is at
> this point in time.
>
> Does anyone know how EMC handles this? I noticed rounding of corners

at least on sharp direction changes. If I reduce feedrate most shallow
direction changes are cut with no problem. I would love to be able to
tell EMC not to "contour" when the trajectory changes are greater than
a set amount. I know I can turn it off or on with Gcode but inserting
these manually ,.. ? Is there a file in Emc with accel/decel
contouring algorithm numbers that can be changed. Or maybe I'm not
understanding settings in the ini file?

Frank