re: parabolas
Posted by
Elliot Burke
on 2001-04-13 18:06:49 UTC
If you just want to draw a parabola in a 2D drawing, consider using a cubic
spline. CAD programs have different sorts of spline curves, you want the
cubic spline. It tries to draw a cubic curve through the points. If you
give it a few points that are on a parabola, the cubic term will be zero and
the curve will be a quadratic. The quadratic curves can be parabolic,
elliptical, or hyperbolic (the conic sections). Thus you'll be able to draw
the other conic sections too. The cubic spline coefficients are
recalculated for every segment between points. Some programs handle the
derivatives at the end points in an odd way, so you might have to pad out
the ends of the curve with an extra point.
Elliot Burke
Date: Sat, 14 Apr 2001 00:18:33 -0000
From: cmsteam@...
Subject: Parabola via CNC?
Hi,
Would some kind gentlemen please fill me in on the Cad programs that
are capable of generating parabolic curves. I've scanned thru 3 thick
books on Autocad with nary a mention. A web search only turned up
EasyCad as a possibility.
Of course the end result has to be convertable to g-code.
Excel can generate the coordinates in a jiffy but, where to go from
there?
Rich
Elliot Burke
HighTide Instruments
spline. CAD programs have different sorts of spline curves, you want the
cubic spline. It tries to draw a cubic curve through the points. If you
give it a few points that are on a parabola, the cubic term will be zero and
the curve will be a quadratic. The quadratic curves can be parabolic,
elliptical, or hyperbolic (the conic sections). Thus you'll be able to draw
the other conic sections too. The cubic spline coefficients are
recalculated for every segment between points. Some programs handle the
derivatives at the end points in an odd way, so you might have to pad out
the ends of the curve with an extra point.
Elliot Burke
Date: Sat, 14 Apr 2001 00:18:33 -0000
From: cmsteam@...
Subject: Parabola via CNC?
Hi,
Would some kind gentlemen please fill me in on the Cad programs that
are capable of generating parabolic curves. I've scanned thru 3 thick
books on Autocad with nary a mention. A web search only turned up
EasyCad as a possibility.
Of course the end result has to be convertable to g-code.
Excel can generate the coordinates in a jiffy but, where to go from
there?
Rich
Elliot Burke
HighTide Instruments