How to create a 3D model from orthogonal projection (Orthographic projection) ?

rune_thorsen229

What is recommended workflow starting from an orthographic projection to 3D representation.
Example :https://civilseek.com/wp-content/uploads/2018/12/orthographic-projection-drawing.jp
I import the JPG in a sketch, lets call it 'projectionsketch' . Then I outline the TOP FRONT AND RIGHT side. 
Is it then possible to project parts of this sketch onto a TOP, FRONT and RIGHT sketch?
Then I guess one should extrude each of the 3 sketches and the intersection should be the model right?

What I really want is to have a parametric model driven by the dimensions on the 'projectionsketch' . For example I would like to make the front a bit longer, so I do it in 'projectionsketch' and everything gets modified automatically.

Sorry if this is a very basic question but I cant find good guides on the topic.

rune_thorsen229

rune_thorsen229 said:

PS: I found this tutorial that shows how to do it but it's not onshape :https://www.youtube.com/watch?v=ZFSV47I7SBg

Thanks everybody.
To summarize: It's not possible to use the  "AutoCAD 2D to 3D Conversion Trick" by 'turning' sketches '90degrees up'  (while keeping original references), though it should be programatically simple. 

rune_thorsen229

PS: I found this tutorial that shows how to do it but it's not onshape :https://www.youtube.com/watch?v=ZFSV47I7SBg

NeilCooke

You would follow the exact same process https://www.onshape.com/cad-blog/turning-your-old-2d-drawings-into-3d

rune_thorsen229

NeilCooke said:

You would follow the exact same process https://www.onshape.com/cad-blog/turning-your-old-2d-drawings-into-3d

Thank you for the link, it confirms that I haven't been off track. BUT... you scale by a factor and add absolute values in extrusion.  Suppose you wanted that to be driven by your original sketch, then doing the copy pasting of the sketch breaks that link. That is why there should be a way to transform or (inviarnt) project the sketch1 or 'projectionsketch' onto the other planes, like in the video i linked to originally. If the feature transform worked on a sketch that would do some of the trick. (By the way, the scaling is a problem if you wanted to end up with a well defined diameter of the disk for example. It would be good to be able to scale so a selected entity would match a given length for example instead of the percentage scaling.)

NeilCooke

It's probably not the best idea to try and drive a model from orthographic views from an imported 2D drawing. That process is really only if you need to make a 3D part that won't ever change. If you want it to be parametric, it is best to model the part from scratch using the dimensions off the 2D drawing as a reference.

owen_sparks

Yeah, to me a "flat paper drawing" is the last resort output of a model if you have a process that won't accept 3D data, rather than what I'd base the mode off.

That said importing some images and positioning them on planes to reference can certainly be useful.  I've used that to reverse engineer stuff from a datasheet.

If it we me doing this for real I'd:-

(a) Pick a view, doesn't matter which and draw that sketch.

(b) Extrude that as a solid.

(c) Add the next sketch on the face of the part (not some plane) and then extrude only which ever "sketch regions" are appropriate.

(d) Repeat for final view

That way there's no messing about with intersections, everything stays parametric and there's no interpretation of what dashed lines mean.

I can't imagine a reliable scenario where a complete 3D model could be made automatically from just a drawing.

Owen S.

rune_thorsen229

NeilCooke said:

It's probably not the best idea to try and drive a model from orthographic views from an imported 2D drawing. That process is really only if you need to make a 3D part that won't ever change. If you want it to be parametric, it is best to model the part from scratch using the dimensions off the 2D drawing as a reference.

Exactly, the whole design could be driven from that 2D drawing (turned into a sketch), but not being able to transform (invariant project) the entities onto the other axis is blocking that design intent. 

rune_thorsen229

owen_sparks said:

Yeah, to me a "flat paper drawing" is the last resort output of a model if you have a process that won't accept 3D data, rather than what I'd base the mode off.

I can't imagine a reliable scenario where a complete 3D model could be made automatically from just a drawing.

Owen S.n.

I see your point, its just a bit counter intuitive argumentation. So why would you be able to transform a model into a drawing? 
In my case I have a 'client' that has made a drawing and would like to turn it into a model and I found it baffling that it was so difficult  when other CAD has this possibility:;https://www.youtube.com/watch?v=ZFSV47I7SBg

NeilCooke

• Creating models from 2D projections is making a big assumption that the 2D geometry is to scale and has not been "fudged" (many a 2D drafter will tell you that it is quicker just to override the dimension value than to update every single view). 
• Creating models from 2D projections is only good for VERY simple prismatic shapes.
  
• I would suggest that you could model that part from scratch in half the time it takes to do in that video.

rune_thorsen229

rune_thorsen229 said:

PS: I found this tutorial that shows how to do it but it's not onshape :https://www.youtube.com/watch?v=ZFSV47I7SBg

Thanks everybody.
To summarize: It's not possible to use the  "AutoCAD 2D to 3D Conversion Trick" by 'turning' sketches '90degrees up'  (while keeping original references), though it should be programatically simple. 

owen_sparks

Sure you could, it's just a copy, paste, transform into position.
The actual questions are whether it's worth the effort and whether the result would be accurate. As Neil said it's almost certainly quicker, easier and more accurate to use other methods.
Owen S.

rune_thorsen229

Jake_Rosenfeld 
From :https://forum.onshape.com/discussion/comment/60481#Comment_60481
Case story for 'raising' sketches to orthogonal projections. 
A collegue propose to make this device that has been sketched as they teach you in school
https://cad.onshape.com/documents/7047b5746d757ac5dd0d5bae/w/7a31455153d74d67bf3400db/e/b4188f5b5481fb09e1f87972

I thought it would be simple to make a mockup, make it parametric, 3D print a small demo and then scale to full size. 
As Onshape 'potentially' could be very easy if it allowed the workflow described here:https://forum.onshape.com/discussion/comment/60295/#Comment_60295
and it shouldn't have taken much time. I notice that my students using Onshape keeps making their designs non-parametric (Im more a programmer than a designer so I don't like inserting konstants) and run into problems when needing to change diameters on the fly. 
Hope that clarifies the workflow I hoped could be achieved in Onshape.