Tangent through a fixed point on an ellipse

This issue must have been covered in this forum in the past, but I
could not find any relevant topics when I did a quick search. So here
goes...

I have an ellipse with a series of datum points placed on its
perimeter. How do I draw a tangent & normal to the ellipse located at
these points?

I have been struggling with this in the sketched mode, but for some
reason wildfire will not allow me to force a tangent line to pass
through a predefined point.

I might be able to eventually figure it out by writing up mathematical
equations, but thought there should be a less painfull way of doing
this.

Thanks

Tim

 

You can do it, but ellipses, conic arcs and splines tend to confuse the
sketcher constraint solver every now and then. (I've had problems getting
the constraint, shut down and re-started Pro/E, and then could get
everything to work. Go figure...)

I've also found working with "centerlines" (vs. "lines") to be more
problematic (wants to break the conincident constraint before allowing
tangency).

If all else fails create planes normal to curve thru pts and reference
them.

If you want to see how it's "supposed" to work; sketch an ellipse, drop a
sketch point on it, start a line on the sketch point and "rubber band" the
line around, approx tangent to the ellipse, and you should see a "T"
highlight when within constraint tolerance. Shift + RMB when it's visible
to lock it in and finish creating the line segment.

 

Are you using the Intent Manager?

 

Tim,
as long as the datum points were created on the curve..length
ratio/actual len you should be okay

create a datum axis tan curve.. pick ellipse, spline .. curve then the
point
create another datum axist >point normal plane the plane the curve is
on and then point you will use it later

now create a plane thru you tan curve axis , normal to the plane the
curve is on
and finally another plane thru the point norma plane axis and normal
to the plane you just created

now you can move all around the curve/ellipse by modifying the length
ratio point, it doesn't do it in sketcher ..but if you need is to put a
cut /hole/ extrusion at at tangent point later into the
curve/spline/ellipse it works