Im aware the 90deg case is currently covered.  I was commenting to the OP
who thought about allowing the trajectory planner to run a little faster
than it can see could end badly even with such a common case.

For 3d profiling CAM usually writes the g-code.  I don't know anyone who
would hand calculate tens of thousands of little segments:)  As such, I
don't know that its necessarily "poor quality".  It has to generate as many
segments as necessary to fit the arbitrary arcs to the specified
precision.  Around tight curves, that requires lots of short sections w/
high changes in velocity.  But you have to go slow within the limits of the
machine around those anyway.  On the longer smooth arcs, it generates
longer segments (Im using Visual mill pkg in Alibre) so no problem there
either.  Are there common CAM pkgs that dont do this well?  I guess if I
set the curve fit in CAM to a very small number (currently using 0.001") it
would bog my machine down.

Like I asked: How big of a problem is this really?  I can imagine a Hass
class machine that can hold tenths at high speed could be fed a huge file
w/ tenths arc fitting.  Even allowing some small  additional error like G64
P0.0001 I can envision a scenario which might not run at the programmed
feed rate.  So I ask again: Are there real world examples of it being a
problem?

Stephen

On Thu, Apr 19, 2012 at 9:33 AM, andy pugh <bodge...@gmail.com> wrote:

> On 19 April 2012 14:04, Stephen Dubovsky <smdubov...@gmail.com> wrote:
>
> > But I see how it might be a limiting factor for a modern Hass class speed
> > machine w/ massive spindle hp and feed rates possible when profiling.
>
> It shouldn't be a limit on any machine with decent G-code. I am
> describing a problem with poor-quality G-code which is made up of
> thousands of very short line segments.
> There is a constraint to at least touch every segment (I think) so
> your concern about the 90 degree bend is covered.
>
> --
> atp
> The idea that there is no such thing as objective truth is, quite simply,
> wrong.
>
>
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