Old Timer Draftsman stubbornly chasing his tail.

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jlondon53
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Joined: Wed Apr 24, 2019 11:26 pm

Old Timer Draftsman stubbornly chasing his tail.

Postby jlondon53 » Wed Apr 24, 2019 11:55 pm

So I'm trying to learn to use FreeCad but back in the Dark-Ages i used a pencil, paper, and straight edge - and a 2D drawing of a top, bottom, and side view was used to create the 3D perspective (hand drawn of course) - not the other way around. In FreeCAD, however, everything is counter-intuitive/backwards for me including all the tutorials/videos. I already know that what I'm asking is probably no longer considered the 'best' way - but I just want to know if I 'can' - or if I'm just wasting my time trying to find a way. To repeat, I want to create a 'part' or '3D image" by FIRST creating a properly dimension-ed 2D front, top, and side view drawing - just like the old days and convert 'that' to 3D perspective - NOT create a 2D drawing from an an imported and/or already created 3d part/image like shown in literally every tutorial I've run across. 'CAN' I do this in FreeCAD? 'CAN' I simply create a properly dimension-ed blue-print and simply go to a different workbench and have it automatically converted to a 3D rendering? Thanks in advance!
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bejant
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Re: Old Timer Draftsman stubbornly chasing his tail.

Postby bejant » Thu Apr 25, 2019 4:02 am

Hi jlondon53, and welcome!
jlondon53 wrote:
Wed Apr 24, 2019 11:55 pm
I want to create a 'part' or '3D image" by FIRST creating a properly dimension-ed 2D front, top, and side view drawing - just like the old days and convert 'that' to 3D perspective
(snip)
'CAN' I simply create a properly dimension-ed blue-print and simply go to a different workbench and have it automatically converted to a 3D rendering?
Sorry but the answer is: No. As one example of how to create a 3D thing, in the Part Design WorkBench ("WB") we usually create a 2D Sketch, define the geometry in that Sketch by assigning Constraints to that geometry, then do some other operation (Pad, Revolve, etc) to move the shape contained in that 2D Sketch through the 3D space in order to create a 3D object. More Sketches are added to the model, and the geometry in those subsequent Sketches are again moved through the 3D space to add or subtract material from the previous state of the model. Each Sketch is somewhat like a 2D view of a portion of your model.

There are other ways to create a 3D thing, but we can't start with a 2D drawing of 3 views, click a button, and have FreeCAD create a 3D shape.

If you'd like to continue with FreeCAD, post an image of what you'd like to create and we can likely help you get started. The FreeCAD workflow to create your 3D thing will probably become clearer for you then.
jmaustpc
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Re: Old Timer Draftsman stubbornly chasing his tail.

Postby jmaustpc » Thu Apr 25, 2019 4:23 am

bejant replied whilst I was typing and we pretty much say the same thing, I will post my response anyway in case it helps.
jlondon53 wrote:
Wed Apr 24, 2019 11:55 pm
To repeat, I want to create a 'part' or '3D image" by FIRST creating a properly dimension-ed 2D front, top, and side view drawing - just like the old days and convert 'that' to 3D perspective - NOT create a 2D drawing from an an imported and/or already created 3d part/image like shown in literally every tutorial I've run across. 'CAN' I do this in FreeCAD? 'CAN' I simply create a properly dimension-ed blue-print and simply go to a different workbench and have it automatically converted to a 3D rendering? Thanks in advance!
That is pretty much impossible, however in a simplistic sense, for simple cases, that is what Sketcher does in PartDesign WB. Create a fully constrained 2d sketch then "Pad" that to a solid.

You should be able to learn PartDesign workflow easily with your back ground. But rather than trying to make the 3d solid from one massively complex 2d drawing, think in terms of splitting your workflow into several more simplistic steps (which is what a feature is).

For a very simplistic example, if you want a cube with a hole through it, create a 2d sketch only containing a fully constrained square, then Pad that sketch to get the cube, then 2d sketch a fully constrained circle and "Pocket" from that circle sketch to create the hole. Of course in that simple example, you could have included the circle within a square in one sketch and "Pad" that one sketch, the result would be a cube with a round hole in it. However that circle must be fully within the square, if an edge of the square and circle where to touch or overlap, the Pad would have to fail as it would not definitively define the resulting solid.

Just work step by step with simple examples and you should very quickly understand the logic.

Generally FreeCAD like most modern CAD programs defines a real 3d thing, where as 2d CAD is just defining a "picture" of a real thing as viewed from some arbitrary direction hence is useless for any further interpretation (or calculation or FEM or Path for CNC or Mesh for 2d printing or ray tracing for high quality visualisation etc.) without a human except for simple 2d examples like CNC laser/water/oxy cutters cutting out plate or similar.

You can use FreeCAD Draft WB for "old fashioned" 2d CAD work, but to FreeCAD they are "real" 2d geometry objects sitting in 3d space.

The 2d TechDraw WB is for, as you say, extracting an old fashioned 2d drawing from a 3d object, to print it on paper or a PDF etc. as required typically for human visualisation, legal requirements like building approvals, or a simplistic universal way to "exchange" data so in that sense somewhat like an exchange format.

Anyway, spend a few minutes in PartDesign and I think you will quickly understand it. Note that you create a "body" (a single contiguous solid) by building it up from "features". E.G. the Body would be the cube with a hole through it, it would contain a first feature (a Pad to make the cube) and a second feature (a Pocket to create the hole through it)
freedman
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Re: Old Timer Draftsman stubbornly chasing his tail.

Postby freedman » Thu Apr 25, 2019 5:26 am

I don't do this much anymore but I wrote a list of tips when I first started here. Maybe something will help you. It's about the 3rd post in, about a page worth of ramblings.

https://forum.freecadweb.org/viewtopic. ... 9&p=258352
Last edited by freedman on Thu Apr 25, 2019 4:52 pm, edited 1 time in total.
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HarryGeier
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Re: Old Timer Draftsman stubbornly chasing his tail.

Postby HarryGeier » Thu Apr 25, 2019 5:33 am

Hi Jlondon,

well, as many years ago i had to introduce Solidworks intot a buinch of "old timer" engineers and draftsmen, i fully understand your problem.

You could think of a 2 step approach .
First, you , in mind , apply your 2d, 3 views idea to 3 areas of the paper. Which are in fact so called datum planes in Part Design. The create sketches on each, representing your final model. We call such MASTER sketches. Then when done arrange them in 3D space so you can create the real sketches , from which the features will be built using the master sketches for carbon copying or referencing the objects.

harry
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PrzemoF
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Re: Old Timer Draftsman stubbornly chasing his tail.

Postby PrzemoF » Thu Apr 25, 2019 11:52 am

@jlondon53: 3D modelling is closer to machining than to drafting. Think about the part that you want to make like you had a block/cylinder (or other shape) of a raw material, then you want to cut this surface, drill a hole there.
paullee
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Re: Old Timer Draftsman stubbornly chasing his tail.

Postby paullee » Thu Apr 25, 2019 1:43 pm

Hi, starting from something simple like this? I never really use FreeCAD Part Design Workbench before this experiment.

3 sketches to create a solid / part.
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paullee
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Re: Old Timer Draftsman stubbornly chasing his tail.

Postby paullee » Thu Apr 25, 2019 1:43 pm

FreeCAD file
Attachments
Test_ 3 Sketches for A Part.FCStd
(26.48 KiB) Downloaded 12 times
jlondon53
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Joined: Wed Apr 24, 2019 11:26 pm

Re: Old Timer Draftsman stubbornly chasing his tail.

Postby jlondon53 » Thu Apr 25, 2019 11:27 pm

Thank you to all who have replied for your generous time and efforts to help. I now have the answer to my question which is "NO". While I appreciate some of the other technical help many have given, I do have some very basic, self-taught, understanding of the FreeCAD program, workbenches and procedures although I know it's probably hard to believe. My personality and weird way of learning often causes me to get hung up on the smallest things and until I get past them I end up "chasing my tail". FreeCAD is a deep and amazing well and I was just wasting my time trying to find a way to do something it is evidently not able to do although it does seem, to me, that what I was trying to accomplish would be a no-brainer for a program of this magnitude. I'm not computer illiterate - but do only know enough to be dangerous (grin). Thanks again!
jlondon53
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Joined: Wed Apr 24, 2019 11:26 pm

Re: Old Timer Draftsman stubbornly chasing his tail.

Postby jlondon53 » Thu Apr 25, 2019 11:35 pm

bejant wrote:
Thu Apr 25, 2019 4:02 am
Hi jlondon53, and welcome!
jlondon53 wrote:
Wed Apr 24, 2019 11:55 pm
I want to create a 'part' or '3D image" by FIRST creating a properly dimension-ed 2D front, top, and side view drawing - just like the old days and convert 'that' to 3D perspective
(snip)
'CAN' I simply create a properly dimension-ed blue-print and simply go to a different workbench and have it automatically converted to a 3D rendering?
Sorry but the answer is: No. As one example of how to create a 3D thing, in the Part Design WorkBench ("WB") we usually create a 2D Sketch, define the geometry in that Sketch by assigning Constraints to that geometry, then do some other operation (Pad, Revolve, etc) to move the shape contained in that 2D Sketch through the 3D space in order to create a 3D object. More Sketches are added to the model, and the geometry in those subsequent Sketches are again moved through the 3D space to add or subtract material from the previous state of the model. Each Sketch is somewhat like a 2D view of a portion of your model.

There are other ways to create a 3D thing, but we can't start with a 2D drawing of 3 views, click a button, and have FreeCAD create a 3D shape.

If you'd like to continue with FreeCAD, post an image of what you'd like to create and we can likely help you get started. The FreeCAD workflow to create your 3D thing will probably become clearer for you then.
Thanks. Your first sentence told me exactly what I needed to know (grin). The rest is helpful as well.