Creating a parabola in WF2, 2

[texaspete]

Hello gang. I need to create a parabola for rear tail lamp for a van. It is the backup and stop/turn cavities. I am trying to create the parabola without using the technique that PTC recommends. they recmommend a new coordinate system located some where in the tail lamp and then by trail and error, locate the parabola in the correct spot. I am creating a 2d sketch in wf2.0. My goals is to use angles, a par, dimension, ex, .75 or .50; a par value that is equal to a parabola. I know that I have seen this sketch somewhere. Can someone help me out as to how to create this parabola. - thanks texaspete

 

[Guest0527211403]

In sketcher, a conic arc can let you create a parabola in the method that you have described. You can find it in the flyout menu for arcs.

A conic parameter of 0.5 will give you a parabola. Higher values give you hyperbolae and lower values give you ellipses.

See pages 38-40 of the document at

http://pkatuch.szm.sk/download/sketcher.pdf

for more details about the conic parameter.

 

[texaspete]

I have exhausted my knowledge of trying to sketch a parabola. I can create only a portion. From the "X" axis and the focal point on the "X" axis to the vertex which is on the "X" axis and the "y" dimension of the end of the parabola curve. Could someone reply to this posting showing me what to type in the equation window.
PTC has x=D*cos(180*t), y=B-C*cos(360*t), z=0.
I think I have to some variable assigned to "A, B, C, t" before the equation.

I have no clue what to type. I think the equation window is notepad.
thanks to all. texaspete

 

[jeff4136]

/*Parabola by equation
/* For cartesian coordinate system
height = 3
span = 4
x = (span/2) * cos(t*180)
y = (4 * height / span^2) * x^2
---------------------------------

The suggestion to use a conic arc with rho = 0.5 is easier, though.
See the following links for some layout geometry.

http://www.mcadcentral.com/proe/forum/forum_posts.asp?TID=29611&TPN=2

http://www.mcadcentral.com/proe/forum/uploads/jeff4136/2006-01-20_165544_parabola_wf2.prt.zip

(WF2)

Very simply, though, to create a revolved parabolic surface 1 high x 2 dia:
Reference points will be [1, 0], [0, 1], [0, 2].
Axis of revolution [0, 0], [0, 1].
Conic arc [0, 1] to [1, 0].
Tangent directions; normal to axis and coincident with a line from [1, 0] to [0, 2].
Rho = 0.5.

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