Abstract Chat about 3D Modeling Techniques With Strong Feelings and Emotions

[CI]

There was a question about learning 3D modeling, and transitioning from 2D drafting to 3D modeling.
I can help with the way I do it.

There are many trains of thought on the "best" way to do 3D modeling.
I don't know if anyone would consider my 3D methods the "best", or even consider them "good", but they do work well, and work particularly well if someone is very good at 2D CADD, and transitioning into 3D modeling.

The "right" way to do 3D modeling of course is the method that works best for YOU.

.

[CI]

I started manual drafting (vellum commercial drafting paper on a drawing board) in college, about the turn of the stone age (1976), and leanred to make engineering drawings.
We made all of our own engineering drawings manually using this method until the IBM-PC came out, and then some simple drawing programs began to emerge.
I think this was about 1986.

Autocad came out some time after 1986, and competed against many other CAD programs.
After many years, Autocad emerged in most Architectural/Engineering firms as the dominant program.
I learned AutoCad in 1995, and it took me perhaps a week to get somewhat proficient using it.

AutoCad 2D was easy because all I had to do was duplicate on a computer screen what I had been doing manually for years on a drafting table.

All was well in the CAD world until I decided in 2012 to learn 3D modeling, using Solidworks.
I basically collided with reality when I realized that 3D modeling was not going to be as easy to learn as 2D AutoCad.

It took me a year of struggling to get to the point where I could begin to use a 3D modeling program.
The sad thing is, if I would have had access to a good tutorial, I think I could have become proficient in perhaps a month.

Here are my thoughts on why learning 3D modeling, coming from a 2D CAD environment, was so difficult.

.

[Dave Otto]

Pat, I think you are the only person in the country that uses the process that you do.   
Seems that we had this discussion not long ago.

Dave

[CI]

2D CAD is just like manual drawing.

You place the cursor, draw a line, raise the cursor (so to speak), move the mouse to a new location, draw a new line or shape, and repeat that over and over again, on what is basically a sheet of paper simulated on the computer screen.

When I started trying to learn 3D modeling, my first question was "Where is the paper ?".

LOL, well as it turned out, in 3D there are infinite numbers of sheets.

Second question was "Where do I start drawing; ie: how do I get to the paper so I can start drawing ?".

Third question was  "Now that I have drawn a shape, such as a circle, and extrude it into a solid, how does that become an engine part".

I watched some tutorials, but the problem was that I did not have a conceptual foundation/understanding of what the overall goals and objectives of 3D modeling, and so without that knowledge, the tutorials had little relevant meaning.
The tutorials did not create engine parts either.

.

[CI]

Pat, I think you are the only person in the country that uses the process that you do.   
Seems that we had this discussion not long ago.

Dave

Well then it is obvious that this is not the thread for you, so don't waste your time reading things here that you have previously discussed.
I don't think your point is relevant in learning 3D at all.
Folks in some countries drive on the wrong side of the road from what is done here, but it is all good, right ?
Different strokes for different folks.

I am going to lay out my method, and people can use it, or ignore it (in part or full).
If anyone has another method, please start your own thread, and illustrate your method in your thread.
Thanks much.
There is no need to discredit someone's method just because it differs from yours.
There are literally many many ways to slice a loaf of bread.

Edit:
The method used to create 2D sketches has no bearing on 3D modeling; it a transparent thing that nobody would even be aware of had I not mentioned it.
The 3D modeling methods remain the same regarless of how the 2D sketch is generated.
Its like saying "Well you use an Apple computer, and I use a Windows computer, so your drawing methods are not good".
Totally irrelevant.

To clarify, I often create sketches in Autocad 2D, and import them into Soldworks, to start an initial sketch/model.
Works well for me, but is totally optional, and one can do all the sketching in the native 3D modeling program if desired, but sketches can also be imported.
I have imported most of the initial sketches for most of the 3D models I have made, because sketching in Autocad is infinitely easier for me than sketching in Solidworks.
One should use the method that works best for you.
.

[Dave Otto]

Sorry I thought that I was posting to the Alibre thread, I will show myself the door.

Dave

[CI]

 

[CI]

Conceptualization:

Conceptualization was the key for me to be able to start using 3D modeling.

I would look at an object like an engine part, and try to figure out how I drew a 3-dimensional object on a flat computer screen.

The answer is that you have to start modeling the object by first drawing a sketch in 2D on a flat screen, and then doing something like extruding that sketch into a 3-dimensional object.

Where does the first sketch come from ?

The method I use is to visualize cutting a section for a 3D object.
Slicing an orange in half creates a circle on the perimeter of the edge.

A rectangle can be sliced on its long or short axis, to create a rectangle or square, or can be cut on a diagonal, or at a skewed angle.

A shape such as a small carburetor can be cut in many different places.
I generally start by cutting in a place that can be used to produce the largest shape that is within the entire body of the carburetor.

An ah-ha moment occurred when I remembered the old Play-doh extruder.
The extruder has a number of dies that can be used, and if you cut off the shape that is being extruded, you are basically created a sketch for that particular shape.

You are sketching the outline of the die in the extruder.
Change the die (sketch), and the shape of the extrusion changes to match.

.

[CI]

Where do I start Drawing ?:

I am not trying to dumb-down this topic, but rather just recall what I had to mentally conceptualize, before I could start using 3D modeling effectively.
I am sure some folks can almost automatically understand 3D modeling, but that was not the case with me.

I conceptualized having three drawing tables on the screen at the same time, which is the X, Y, and Z planes.

Unlike 2D CAD where there is only one plane to draw on, in 3D modeling, you have to select which plane you want to begin drawing (sketching on).
This was very confusing for me, since the first program I started using would automatically jump on and off of the plane after you were finished sketching.
I would sketch, the program would jump off the plane, and I would be back out in space looking at the three planes again.
WTflock is happening, I recall saying.

.

[crueby]

Love the play-dough analogy!

Another way to 3d-ify from the sketches are to rotate a portion of the sketch - draw a cross section, pick one side and the axis, and it will rotate the cross section around the axis to make the object. Lots of other tools too - lofting from one shape/sketch onto another one along a path, that sort of thing. Once you get the hang of it its amazing what you can draw up quickly, but it does take time to learn. Watching the tutorial videos, as mentioned, is a great way to get towards the 'aha!' moments.

[CI]

Sphere Example:

So first thing is to learn how to pick a plane, and rotate that plane so it is flat on the screen.
Then you draw a 2D sketch on that plane.
Next step is to extrude that sketch into a solid, and I do that while I am on the plane in my program.

In this example, I got on a plane, lets say the X plane (not really critical which plane at this point), drew a circle with an origin at the center point of the X,Y,Z plane, drew a vertical axis, cut off half the circle, and then used an extrude-rotate (I forget the exact command name) to rotate the half circle sketch around the vertical axis.

I find it important to start the center of the sketch at the X,Y,Z origin, for reasons that can be illustrated later.

.

[CI]

Various Shapes Examples:

If a different shape is desired, draw a different sketch, and in this case it is also revolved around a vertical axis.

.

[CI]

Various Shapes Examples:

If a different shape is desired, draw a different sketch, and in this case it is also revolved around a vertical axis.

.

[CI]

Model a Shaft:

Draw a circle at the origin, and extrude it in one direction (or extrude from the center in both directions at the same time) into a shaft.
You can pick the shaft and modify the length.
You can pick the circle sketch, and change the size of it to modify the shaft diameter.

.

[CI]

Flanges on a Shaft:

You can draw a shaft, and add flanges onto the ends.
One way to do this is to pick the end of the shaft, tell the program to go to that sketch plane (methods vary about doing this), rotate that surface flat to the screen (I forget the button name that is used for this), draw a circle on the end of the shaft, and then extrude that circle either inwards or outwards.
If you extrude the new circle inwards when creating the flange, then if you change the length of the shaft, the flange remains the same thickness, but moves in synch with the end of the shaft.

If you want flanges on both ends of the shaft, no need to draw the circle twice, just mirror the flange across the initial sketch plane to the other side.

.