Re: Simple Vector Feed Rate Setting Question

Dan,

Ahh. Mixing angular and linear moves in one block is something of
a source of consternation for control authors. For TurboCNC v3.1,
this is how it works:

In a case where one angular axis moves with a linear one, the
feedrate is applied to the linear axis, and the angular one moves
along with it. They both start and end together, and accelerate in
sync.

If the angular axis moves alone, the feed is in degrees/second.
This is to assist the HSM's, whose parts are typically on about the
right scale for deg/sec and ipm to be similar. Deg/min is way too
slow.

The "gotcha" is when the angular axis moves a long way in
comparison with the linear one. In order to keep pace with the
linear axis, it may have to move pretty fast - perhaps almost a rapid
move! So the true "chip load" feedrate ends up varying; which is
frustrating.

One workaround: set up the rotary table as a linear axis such that
one rev is 2.5" (a typical circumference for a wedding band). Then
your code should work much better. Naturally you would adjust your
macros so that 360 deg = 2.5" or whatever.

Another is for me to put in a special Mcode to override/enable the
max speed for an axis, so you wouldn't have to change any code except
to add an Mcode before the first cut and before the "rapids".

Very nice rings, by the way!

Dave Kowalczyk
Everett WA
TurboCNC and CNC stuff --> http://www.dakeng.com
Support forum --> http://groups.yahoo.com/group/turbocnc

--- In CAD_CAM_EDM_DRO@y..., "Dan Statman" <dan.statman@r...> wrote:
> This seems to be exactly what is happening. Is it very difficult
to look at
> both axes movements and calculate the feedrate based on not
exceeding the
> designated rate for either axis, even if one is a rotational axis?
This
> seems like it would be a common problem since most people with a
rotational
> axis connected to their CNC will use it concurrently with a linear
axis.
>
> How can I get around this problem? Does it matter what order the
axes are
> identified in a G01 move as to which axis gets the feedrate control?
>
> My current work-around method is to set the maximum speed of the
rotary axis
> to the rate at which I want to cut, but this makes rapid moves
anything but
> rapid.
>
> Dan.