How to draw a vertical pyramid?

[khoshravan]

In the attached drawing, I want the angle between planes ABEH and ACDB to be 90 degrees. How should I define the pyramid to obtain that shape?

 

piramid.dwg

[paulmcz]

Can't find plane ABEH or points E and H. Where are they?

[Dana W]

I am not sure what you mean by a plane other than the ABCD plane. Any way, the only 90 degree angles in a pyramid are the four corners of the base.

[Dadgad]

From the sound of things, you want a right pyramid, I think you want to use LOFT to POINT.

 

A pyramid (from Greek: πυραμίς pyramis) is a structure whose outer surfaces are triangular and converge to a single point at the top,

 

I should add that I haven't opened the attached drawing, and it sounds like you want a four sided based right trangle, same technique to do it.

Edited December 25, 2016 by Dadgad

[ReMark]

Or use the Primitive: Pyramid.

[steven-g]

As Dana W said the four corners on the base can be 90 degerees, if you have 90 degrees between the verticle faces then it will be a cube.

[khoshravan]

Can't find plane ABEH or points E and H. Where are they?

Sorry I uploaded a wrong drawing. In this drawing I want plane OAB to be perpendecular to ABCD plane.

[khoshravan]

From the sound of things, you want a right pyramid, I think you want to use LOFT to POINT.

 

A pyramid (from Greek: πυραμίς pyramis) is a structure whose outer surfaces are triangular and converge to a single point at the top,

 

I should add that I haven't opened the attached drawing, and it sounds like you want a four sided based right trangle, same technique to do it.

 

Dear Dadgad

You are correct. I want a right pyramid. Although your notes are helpful but couldn't get a hint from your notes on how to do it?

I am new to 3D and don't know how to do it. The only new command I saw in your reply is loft and I will give it a try.

[paulmcz]

Is this (attached) what you are looking for?

 

If it is, here is what you do:

 

Set your view to "SE isometric"

Draw a square 1.42 x 1.42 (A-B-C-D)

Extrude the square to 1.25 height. Let's call the new solid a "base body"

Let the new upper plane (the one parallel to base A-B-C-D) be a plane A1-B1-C1-D1

Change the UCS to "Front"

Draw a polyline D-B1-D1-close

Extrude new polyline to 2 units height.

Subtract newly created body from the "base body"

Change UCS to "Left"

Let's a midpont of the edge A1-B1 be "E" point (you can place the "E" point anywhere along the edge)

Draw polylines A-E-A1-close and polyline B-E-B1-close

Extrude both polylines to 2 units height

Subtract the two new solids from "base body"

 

Done.

pyramid.dwg

Edited December 26, 2016 by paulmcz

[Dadgad]

Dear Dadgad

You are correct. I want a right pyramid. Although your notes are helpful but couldn't get a hint from your notes on how to do it?

I am new to 3D and don't know how to do it. The only new command I saw in your reply is loft and I will give it a try.

 

Create the base of your pyramid.

At whichever vertex you want to be the right angle along the Z axis, create a point.

Switch to an Isometric perspective, select the Point and move it up orthogonally along the Z axis, to the appropriate distance, representing the height of your pyramid.

Start the LOFT command, select the POint option from the commandline prompts, then just follow the prompts, very simple.

 

If you look at my screenshot, you can see the point which is highlighted with a circle, and now selected, above the left most vertex of the triangle on the left side of the screenshot.

Loft to a Point is pretty darned straight ahead, as long as you are in an isometric perspective, so you can see what is going on.

Edited December 27, 2016 by Dadgad

[GP_]

How should I define the pyramid to obtain that shape?

From your dwg:

Edited December 27, 2016 by GP_

[ReMark]

I'd like to know why you felt it was necessary to set your crosshairs in an isometric plane in the drawing attached to post #1? Care to explain?

 

Do you know how to reorient the UCS?

[BIGAL]

Using Gp method No ucs etc create POINT mid point of base line use properties change Z of point, Ctrl pick top pyramid pick Node all done then erase node. Autocad always has so many ways to do one task.

 

Also thought about 3dfaces convert to surface convert to solid. Not sure how to pick top of pyramid point if it was to be automated..

[ADSK2007]

Here is how you do it - See attached

 

 

Adsk