How do i locate a point on any particular face of a solid?

[Dhiraj Bhandary]

hi..
i am using autocad 2004. is it possible to locate a point on a particular face of a solid by using the mouse??? currently, i do it by specifying the co-ordinates.. but the detection of co-ordinates is very tedious....

for eg... if i draw a box.... then i want to draw a cylinder on the front face of the box... then how do i locate the center on the front face of the box??

[SEANT]

Probably the most straight foward method is with the use of "construction geometry". In your example, a line drawn from corner to opposite corner of the face, then "mid" osnap to that line. You may have to orient the UCS to the appropriate face before drawing the circle.

[yedan]

you should be able to use running object snap in 2004 if i remember (its been a while) that should allow you to pick the therotical intersection of the two mid points on your face.

[lucaso]

You need 5 points: 3 of the 3DFace and two of an (imginary) line.
For example:
a 3DFace and a line pointing to it (doesn't need to be pErpendicular)
Command: POINT 'cal ilp(end,end,end,end,end), this will create a point in the coordinate 2D-space of the 3DFace. (mid the ' in 'cal = transparent)
ILP takes 3 points of a surface and 2 points for a vector.
There are more "cute" functions with the CALCULATOR, check it out!!

[Spring]

I advice that using the edgeline of the solid to trim an assistant line, the endpoint of the assistant line being trimed is the point you want. It require the solid face is a planar and using UCS.