Re: Question about angular and linear feedrates

Hi Brian,

Well instead of 0, why not have it assume a radius that gives the same
feedrate, I.E. with my 3.6" /rev equivalent feed, a 1" dia gives nearly
(1.14159", actually) the same feedrate. I haven't tested this! But I'm
thinking then even with out a "radius" parm, it would be a simple mental
exercise to double or halve (or whatever) the feedrate to adjust for
other dia's.

Alan KM6VV

Brian Pitt wrote:

>
> lets keep it simple
> if the control dosent have a register for the A-axis diameter offset
> it should at least be able to do an interpolation based on the user units
> of both axes
>
> in the example Dan gave I'm guessing the software did the position
> interpolation right and the tool path was a smooth helix from
> X0,A0 to X.5,A180 but for the velocity interpolation only used the X-axis
> value and ignored the larger value of the A-axis movement and
> forced the A-axis to move too fast
>
> if the control does have an A-axis diameter offset it can use that
> to calculate the feedrate but if it dosent or if that offset is set to zero
> then the control should calculate the feedrate with the values its given
>
> Brian
>
> On Monday 05 August 2002 01:42, you wrote:
> > What the control really requires is the relative position of the zero
> > point to the centre of rotation of the A-axis so it can calculate the
> > actual coordinates and distances travelled by the toolpoint for all
> > subsequent movements.
> > If the zero point is directly above the centre of rotation and almost
> > touching the work surface of a cylynder then that of course is the
> > radius. I've termed this Initial Tool Offset around A-axis (ITOA) to
> > hopefully save confusion unless anyone has a better term.
> > I assume that the zero point for 4-axis work is normally set at or
> > above the centre of rotation of the A-axis. Is it likely that the
> > zero point would ever be offset in the Y-axis ?
> >
>