I took drafting in classes in school back in the 1980's, and I hand-drew all of my engineering drawings up until 2D CAD programs came along in about 1987.

I finally learned 2D CAD drafting in 1994, and that was a slow process, but not too difficult, since it mimicked manual drafting on a computer screen.

I started learning to draw model engines in 2009, and while I knew how to use a 2D drafting program, I did not know how to design or draw model engines.

My first atttempt to create 2D drawings for one of my dad's engines was a disaster, when I discovered that none of the various pieces that I had drawn would actually fit together when assembled (who knew things have to align on an engine?).

The drawings went into the garbage can, as did some machined parts.

To borrow a Monty Python phrase, "I got better" at engine design, using my 2D CAD program, but I was still having problems visualizing new designs, and was restorting to using cardboard mock-ups to try and figure out some designs.  I was having too many parts not fit or align correctly.

I began to see some very nice 3D work online, some of which was by a guy in the UK. I was most impressed with what could be done with 3D modeling, and vowed to learn how to use it.

I purchased a 3D program in 2012 and began to learn 3D modeling.

Once again, it was a trainwreck. I could not begin to figure out how to use a 3D modeling program, and could not wrap my head around the fundamentals, in spite of seeing both written and video tutorials.

The problem for me was that while it was easily to conceptualize doing 2D drafting on a computer screen instead of on vellum, it was not easy to conceptualize exactly how to translate 2D work, or design work in general, to a 3D program.

I am one of those folks who have to be able to reach a satellite overview of an entire topic before I can begin to see exactly how to use something, and how to use it effectively.

What follows is my paper trail for learning 3D modeling.

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Edited By PatJ on 06/05/2022 12:08:13

I recall loading my new 3D software, opening the program, and being totally baffled at the array of menus and toolbar buttons that were available.

My thoughts at the time were "boy, have I stepped into something deep on this one".

I am a visual person, and I don't learn well by reading text (call me dyslexic, or stupid, or whatever, but I most definitely have learning problems with text-based narratives, and always have).

My approach to learning 3D was to somehow figure out how to use 2D CAD techniques to force 3D modeling to work, but without really understanding the 3D process.

The result was some extremely frustrating floundering around like a fish on a beach, with absolutely no progress for months.

I was finally able to model a few crude shapes in the 3D program, but I still had no idea how a 3D program worked, or what exactly I was trying to achieve.

I distinctly recall asking myself over and over "what the flock am I doing? and what am I trying to do?".

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Edited By PatJ on 06/05/2022 12:17:56

I finally figured out the 2D sketch plane vs 3D modeling space toggle.

When drawing using a 2D CAD program, there is only one sketch plane, which is the X-Y plane, and it represents a piece of paper.

Drawing in 2D CAD is basically "what you see (or draw) on the screen is what you get".

Creating a 3D model from a sketch involves two steps, which are to first draw a section of some object on a 2D plane (just like drawing in 2D CAD), and then toggling over to 3D model, and using a 3D funtion such as "extrude" to extrude that flat shape into a 3-dimensional object.

It took me a very long time to figure out just this simple toggle thing, but there is nothing analogous to it in 2D CAD or in manual drafting.

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Instead of the typical X-Y planes used with 2D drafting, a 3D program has an X, Y and Z plane.

You can create sketches on any one of these planes.

I typically begin my first sketch on the front plane, but it really makes little difference; you can begin on the top or right plane.

So now I am basically doing exactly the same thing as if I were using a 2D CAD program, ie: drawing lines on a flat piece of virtual paper.

We will create a sphere, and will start by drawing a circle, cutting the circle in half, adding an axis, switching to 3D mode, and then revolving the 1/2 circle around the axis to create our sphere (the REVOLVE BOSS/BASE command in my program is used to sweep the 1/2 circle around the axis to create a sphere).

The result is a 3D solid sphere.

Edited By PatJ on 06/05/2022 13:07:31

In this example, whatever sectional shape I draw will be revolved around the vertical axis I drew.

I have created my first sketch plane, and it should be listed on the left side of the screen.

I can right click on that sketch plane name, and toggle back onto that plane, and edit it to create a different revolved solid, as follows:

Note that when I start to edit the sketch I created, the program presents the three planes to me in an isometric arrangement, and I have to pick a button to bring my sketch plane flat on the screen. I am not sure what the exact command in my or other programs is to do this.

Edited By PatJ on 06/05/2022 13:27:33

So basically you are creating a Play-Doh die on the sketch plane, and extruding that shape into a 3D solid.

You can also use your sketch to create a cut, such as using a formed cutting tool on the lathe.

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Edited By PatJ on 06/05/2022 19:28:16

Using method one, we can draw a circle on the front plane, extrude it FROM THE CENTER outward in both directions, and create a shaft.

If we pick one end of the shaft, we can sketch another circle, and extrude it inwards, to create a flange (if that is the correct term), and then mirror that flange to the other end of the shaft.

For round objects, the second method is to draw the shaft and flanges in section, and rotate that section around a central axis.

How to recover if you model expolodes;

1. Hit the "Edit-Undo" button (on my program, it is in the pulldown menu) repeatedly until you undo the problem.

2. In the beginning of my learning 3D, I would use a "Save-As" after every step, and if my model crashed, I could open the last good file.

These days, I never use the Save-As, and I only have one file for each part.

There are parts that are complicated enough that sometimes I cannot forsee which exact method I should use.

3D models are often created using the rotated sketch, additive method, and subtractive method.

On rare occasions I have to start a model over again, and map out a new strategy, but for me, starting over again on a model is very rare.

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One technique I have learned, which is very useful for complex parts, is to take a screen capture after each step, and paste that image into a photoshop program.

This leaves a quick visual paper trail, and should things go wrong, you can glance at your method, and generally figure out a new approach (if needed) quickly.

This paper trail is also very useful if you put a model away for a year or so, and then come back and start working on it again. I can quickly refresh on the approach that I took on any given part.

Here is a paper trail on a part that I modeled (a bearing support block).

Complex models may be intimidating at first glance, but the trick is to break their creation down into one simple step at a time.

Like climbing Everest; you don't jump to the top in one big leap, but rather take one small step at a time, and rest often for recovery.

Edited By PatJ on 06/05/2022 20:42:30

Everyone seems to eventually settle in on their favorite methods/techniques as they learn 3D modeling.

My techniques generally get refined with each model I create, as I discover better/more efficient methods.

The trick is to remember what you did, and how you did it, and thus the reason I use the paper trail for most of my models these days, since my memory is not very good.

There are many many ways to model any given part.

The only way to learn 3D modeling is to use the program, start with very simple models, learn one step at a time, and then keep using the program.

If you get frustrated with the program, put it away and try again another day.

This is how I learned machining.

I would chuck up a piece of metal, machine on it for an hour, ruin the piece, curse profusely, swear that I would never machine again, leave the shop, come back the next day, do the same thing, and by day 4 or 5, I would finally master machining that part.

Persistence is the key.

Few if any people learn machining or 3D modeling overnight.

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Edited By PatJ on 06/05/2022 20:43:48