Re: [CAD_CAM_EDM_DRO] linear, circular, and helical interpolation?

Hi Colin,

Let me give it a try. If you need to move JUST the X,Y, or Z axis (one
at a time), then it is simple to move the bed to a new location. If you
need to move to a point using say, the X and Y axis, and you're not
cutting, then still no problem; you simply move one first, then the
other. IF, on the other hand, you need to move more then one axis, and
you want to CUT a STRAIGHT line, or an ARC, etc., it gets more
complicated. Cut a 45 deg. angle? You gotta move both X and Y axis at
the same rate, so that they end up at the same time. Now, I've heard of
some old machinists who CAN do this, but I'll bet most of us can't.

What is the angle is other then a simple 45? or is an ARC?? THAT's
when we call for interpolation, to get from point A to point B, and
travel a SPECIFIC path. For straight lines, we call this linear
interpolation. We may move 1000 counts in X, 750 in Y, and even some in
Z. All 2 (or more) axis must get to "B" at the same time, and have
proportionate rates. What if we want to put a radius on a corner? We
must move in a CIRCULAR path, and we call this circular interpolation.
Cut a Screw thread? This is Helical interpolation. Add to all this the
need to cut in three planes, XY, XZ, YZ, and it gets fun!

Example: Remember the red etch-a-sketch you had as a kid? Remember how
hard it was to draw a diagonal line? or a CIRCLE??

Hope this gives you an idea of what's going on (and didn't confuse!).

Alan KM6VV


cdoughty@... wrote:

>
> Hi All,
> Can anyone explain what linear, circular, and helical interpolation
> means and why one should have it?
> Regards Colin