Design pattern to create a 3D object from a 2D ground plan

baumar

Hi,

I would like to ask a question and introduce the concept of "design patterns", that is learning and issue with a simple example.*

 create a pyramid from a base plane to a given peak point, as I sketched in Pyramid https://cad.onshape.com/documents/294778f0f2aa9b816d4bccca/w/a87bbbd68e49f2f904fb13c9/e/ad9abb1ee3b6ca4b82398cf7

The four sides of the pyramid should be separate identical parts.


To create the faces of the pyramid, the outer line has to remain constant, whereas the other to lines have to stretch. 
I tried to add another transformation, like scale or distance, but that didn't stretch properly-


Would you know an elegant way how to do that? 

(I was hoping to find a kind of "smart extrude" allowing to pull up the middlepoint and then cut the solid body with diagonal planes, but I didn't manage...) 



* The idea is based on "design pattern"  (cf https://en.wikipedia.org/wiki/Design_pattern ). Simplified a design pattern offers solutions or solutions strategies to a common design problem. 

Design patterns were originally created for architecture and found a large expansion in software programming. 
I guess it could also give valuable contribution to a design tool like onshape. 

Another influence for this are learning bits. They're also used IT, where a complex software is explained in small units or tutorials describing the usage of just one function or aspect of the software. 

daniel_splawski

No worries boss.  

I've updated the model in my original post to create the 4 identical non-overlapping parts that you were looking for.  I used to Extrude>Remove commands to cut away the excess material from the top and bottom edges (Extrude 3 and 4) of the original part and then I used a circular pattern to duplicate/rotate the part to create the other three sides.  Because each part is identical by definition, the circular pattern method of duplicating the parts will save a lot of hassle in the long run.  

daniel_splawski

Is this what you were trying to accomplish?  Now you can adjust the height of the pyramid by manipulating the vertical dimension in the "Aufriss" sketch.  The diagonal line and the base line are then used to define a new plane which is then used for the extruded sketch.  

I'm not too familiar with the transform feature, so I don't know if there's a way to make it work the way you want it to.   

https://cad.onshape.com/documents/5789465ce4b0e65410fa6595/w/05ecf63c6975a11a3565d407/e/793b8182c82d56976954d119

baumar

Hi Daniel,

Thanks a lot for your fast reply! 

If I get it right the solution you suggest is:

Create a plan with the 2 corner points and the peak point, design the triangle and then extrude it. 
Then repeat it for all 4 surfaces. 

I have done this in https://cad.onshape.com/documents/57895170e4b0dbf8509d319c/w/3391396343760f852f755d39/e/05d526af86fb1a355436cb59

It has the bottom of the triangle inclined and not yet even to the surface and the tip will have to be manipulated, that should not be too hard.

But eventually  there should be 4 equal parts, here they are just overlapping. And I'm not shure how to do that...
(I'm sorry for not having written clear, I added it now)

daniel_splawski

No worries boss.  

I've updated the model in my original post to create the 4 identical non-overlapping parts that you were looking for.  I used to Extrude>Remove commands to cut away the excess material from the top and bottom edges (Extrude 3 and 4) of the original part and then I used a circular pattern to duplicate/rotate the part to create the other three sides.  Because each part is identical by definition, the circular pattern method of duplicating the parts will save a lot of hassle in the long run.  

baumar

Hi Daniel,
brilliant, that's 2 flies in one swoop...

thanks a lot!

PS I wished I was your boss
If ever you are looking for a job to assist and review my design, let me know !-)

daniel_splawski

Thanks.  Before you call this file finished, you may want to take a close look at the ground plan sketch.  The diagonal lines don't exactly intersect the origin so the edges of the pyramid don't meet perfectly. 

baumar

Mmh, I see now what you mean. Good eyes - better then mine, but they might be a bit older then yours... and good point!
Are you saying the corner points do not match the lines in the sketch called "groundplane" and thus the planes are not right and thus the extrusions? But I don't see the error rsp how to fix it...
Do you know why they don't coincide - rsp what to do that they do coincide?
I tried to match the corner points with the lines in the sketch groundplane, but either it remains undefined or gets overdefined. 
Would it help to set a point at each corner in the ground sketch?

Thanks a lot for your valuable help, boss !-)

Cheers

Markus

daniel_splawski

I'm not exactly sure how everything was constrained originally so it's tough to say.  To fix it i just deleted everything from the original sketch and started fresh with a center point rectangle on the origin.  Then I constrained one side to be equal to the adjoining side, making a square, and then gave one edge a dimension, thus fully constraining the shape.  After that I just used lines to connect the origin to each corner of the square.