creating a line 1

[rb1957]

apologies if this is too dumb a question but i've been trying to draw a line normal to a plane, through a point. i'd settle (actually this is what i really wanted) for a tangent starting at the point of tangency. neither of these fairly obvious constructions seem to be allowed ??

what i ended up doing was creating a rectangular co-ord system at the point and drawing lines along the axes ... but that seems a pretty obscure way of creating an orthogonal set of lines ??

next call would be to the "help"desk ...

 

[ThomasH]

Hi

One way to do it might be this:

Greate a point on the plane. Then copy the point normal to the plane (surface) and after that create the line between the two points.

I can't find a "normal to plane" command, only perpendicular to line :-(.

Regards

Thomas

 

[trainguy]

rb,

The amazing thing about FEMAP is that there are usually about 19 ways to the the same thing, and the help desk can often suggest a way you haven't tried.

If the point you already have is not on the said surface, I personally would try Modify/Project. I know you can project nodes onto surfaces, but because I'm not at my work PC, I don't know if there's a "Point onto surface" option.

You could always create a node(!) and project it onto the desired parasolid surface, then generate lines or other geometry snapping to the nodes.

The "project" command has bailed me out in the past.

As far as your reference to tangent lines, I'm having trouble visualizing the question.

tg

 

[rb1957]

thx for the thoughts ...

tom ... tried "perpendicular to a line" ... thought why the heck did it do that ? ... oh, it picked the "wrong" perpendicular line ! damn, how can i control which perpendicular it chooses ??

tg ... good idea, but no, the point is on the surface. to me they're obvious constructions ... a line normal to a surface thru a point,
or a line tangent to a curve, starting at the point of tangency, projecting a distance.

one "trick" i've noticed is changing the "method" ... using "on point" will load the co-ordinates of the point into "locate".

 

[trainguy]

Can't you copy some geometry (point or line) using existing geometry to define the vector?

tg

 

[trainguy]

Another trick:

When the locate window appears, select the same point twice but to add a value to one of the cells of the second point's coordinates. This is an easy way to define a vector that is parallel or orthogonal to the active coordinate system.

tg

 

[rob768]

create a workplane in the plane you got and used the coordinate system of the plane. The z-axis is perpendicular to the plane

 

[rb1957]

yeah rob, pretty much what i'm doing ... i posted that i was creating a co-ord system to create a line mutually perpendicular to two others; just thought this was a pretty esoteric way to do it ...