Re: Contouring and CVV

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

> Fred,
>
> Huh?
> When I am programming centerline, using a large tool (being aware
> that the radius of the tool is "adjusting" REAL f/r), I insert

an "f"-

> word to get back to the intended f/r. Same as slowing for inside
> corners when pocketing. Why doesn't this work!? (Since I think it
> does) Same with crack-the-whip, if I'm understanding your usage of
> the term.
>
> All these things were well understood and used by manual

programmers

> before Computer CAM systems became common.

By some only, and then usually after they learned the hard way. Have
you seen it documented in any of the CNC texts? I have read at least
2 cover to cover and do not recall the subject coming up.

> >Fred wrote:
> <snip> Only works if the control is aware of the tool size.
> <snip>
> >I view constant velocity contouring as a compromise over what

people

> >will spend for an option that potentially only 5-10% of a

controller

> >manufacturer's customer base will use.

Sure, if a controller is designed for general machining, it could be
used in steel, aluminum, or wood production applications. In steel
the CV may never be an issue. Aluminum has a slight chance,
depending on the size of material to be produced, same for wood. How
many controllers cannot do cuttercomp? Those have NOT made the
investment no matter what, as they cannot properly develop tool edge
contouring. That leaves many hobby class controllers behind. Those
few that can do cutter comp, do they properly compensate for the tool
edge velocity or still simply make the tool center have a planned
trajectory? Again it is an investment that few of the hobby class (
probably none, even including EMC) make because 1) do it manually if
you need it 2) sloooooooowwww cutting speeds in metal, especially on
hobby class machines don't need it. Cutting aluminum sheet and
routing wood, foam, and similar sheet goods needs it. Only a small
percentage of the hobby class customers *need* or even *want* it.
Hence the capability is scarce. These things tend to change when
discussed. ;-) Hopefully. <VVBG>


Best Regards,

Fred Smith
IMService