how to draw parabola with focal point
I can’t think of a way of creating a parabola and it’s focal point in LB. Many years ago I did write an NC code editor/generator that has this ability though. Is this a one-off or is this something you’re going to want to do regularly?
What’s the focal length and dimensions of the parabolic curve as I should be able to generate one for you?
Thanks Marcus, I think i will draw it out in graph paper .
If you can give me the focal distance etc I can get one done for you in a few minutes.
X=150mm F=60
Just to clarify is X the diameter, radius or depth?
x=radius 60=depth
How does this look? This has a focal length (F) of 60mm with a 150mm radius. Let me know if I’ve misinterpreted what you want.
Parabola F=60, Dia.=300.lbrn2 (12.1 KB)
EDIT: BTW, the circle denotes the position of the focus.
1 Like
Thank you looks good. Thanks for lightburn, really a great program
Good, don’t forget to let us know how the project turns out.
FYI: The geometry is approximated with a bunch of circular arcs.As a result the focus won’t be a single point but spread over a distance.I’ve just done some checking of the geometry and measured the spread to be 0.16mm.
Hopefully this is good enough for your purposes but if you need it more accurate I can do another with more points/arcs.
4 Likes
If you are up to speed on your algebra, you may find this site useful.
1 Like
Just thought I’d try it in FreeCAD:
You need to convert the parabolic curve to b-spline before you export it as DXF but it seems to work and it might be more accurate than my approximation.
Here’s the DXF if you want it:
Parabola F=60, Dia=300 from FreeCAD.dxf (5.3 KB)
1 Like
I hate you guys. I had to miss recesses just to learn to divide.
4 Likes