How to Quickly Design a 3D Model Using Basic Shapes

I have been designing my own parts, printing and putting them to use for some time now.

In all of these projects, I've created all of my designs with a very simple approach.

However, this wasn't always the case.

Overcoming my limitations

• When I first got started with 3D printing, I began experimenting with models that were freely available online
• Although this got me started with printing, it bothered me that I wasn't able to print my own creations
• As most hobbyist will agree, I tend to put my spirit into my creations, but in this case, that was easier said then done!
• In my college years, 3D Modelling software (especially the free ones) were hard come by and I was used to designing things using conventional methods of drawing
• But these days, with so many choices, I felt it was almost an injustice to not try and learn at least one 3D Modelling software at the very basic level
• Over the past year or so, I began experimenting with Google SketchUp - I was exposed to an early version of this software in the past and decided that I will start my journey into uncharted territory with something I was familiar with
• After countless tries and armed with some self-taught elementary skills, I was able to design, print and use my first real part to solve a real problem!
• Inspired by this success, I went on to create and print few more of my own creations

For some time now, I wanted to write about my journey into the uncharted territory and how I was able to become self reliant in the world of 3D printing. In this IBLE, I will demonstrate how I went about designing a 3D model for one of my most recent projects by applying these simple, self-taught techniques.

Along the way, I will also point to some problem areas I bumped into and how to get around them.

For the purposes of this IBLE, I will be demonstrating the design approach with two tools that I frequently use:

Google SketchUp Make - the latest free version can be downloaded from here

MeshLab - a free tool open source tool to work with 3D Meshes downloadable here

NOTE

There are many number of free tools available online and therefore the design approach here should be applicable to other tool sets as well.

I use MeshLab at the most basic level, but if you want to know more about what it can be used for, the link to the MeshLab page should give you more information about its capabilities

Just because I'm using the tools that I'm using - it does not automatically make this IBLE about Google SketchUp or MeshLab.

Therefore, details on how to download and install these tools is not elaborated here. Besides, there's no shortage of online resources that can help you get through the installation process.

Only bare minimum features of SketchUp are described in the context of building the model step by step

So what is it then?

In my experience, I've found that it was lot easier for me to go buy a 3D printer, set it up as per instructions and get it ready to print.

And to print something, it's as easy as going up to a site like thingiverse.com, download a "thing" that closely conforms to your requirements and start printing.

But if you're like me and want to print your own creation, then you'll find that it's a very frustrating process to get something from an idea to a 3D model, let alone print.

Not unless, we begin with a little simplicity and an approach to go with it.

And that's what this IBLE is about!

The visual shows some of the features of Google SketchUp Make that we will be using to design and build the 3D Model.

1. The Select tool will be used to select parts of the model
2. To construct the basic 2D model, we will be using Line, Circle and Arc features
3. To extrude the third dimension (or 3D), we will use the Push/Pull tool
4. For additional modifications, we will use the Offset Tool
5. To move the design across the drawing surface, we use the Pan tool
6. To swivel the design around in empty space, we use the Orbit tool

Google has amazing documentation on how to use these features that are very intuitive to begin with, and therefore adding details on how to get started with them here lacks merit.

Once you're ready, fire up Google SketchUp Make to bring up the design surface.

To have an easy point of reference, we will start drawing out the design at the Absolute Zero or the Origin point which in this case is the intersection of the Red, Blue and Green Axes.

NOTE

Every time SketchUp program is started, the Select Tool will be the one that would be active by default

The model we want to design is comprised of a few circles and a couple of arcs.

Note that the dimensions of the part are not important and as mentioned before, we will be concentrating on the approach and not dimensional accuracy. And with enough practice, you can go about designing a part with proper dimensions as applicable to your design.

1. Drawing the first circle is as easy as selecting the Circle tool from the menu bar, clicking on the Origin point and dragging the mouse pointer to the required diameter, and letting go of the mouse pointer
2. An alternate approach would be to simply start typing the radius of the circle as you drag the mouse pointer before you release it
3. The numbers you type will automatically show up in the "dimensions" box located in the bottom-right corner of the screen
4. Using the same technique, draw the second circle inside the first
5. Next, we need to draw another pair of concentric circles that will be the other end of the part we're designing
6. For this, use the Line tool to draw a line from the center of the first pair of circles - drag the line along the Red axis until you're satisfied with the length of the part
7. With the other end of this line as the center, draw a couple more concentric circles - the diameters of this pair doesn't have to be identical with the first
8. Lastly, clean up parts of the line that lie on the inside of both the circles
9. Use the Select tool, click on each segment of line and hit the DELETE key to delete all segments

What you have now are a couple of circles separated by a distance.

NOTE

• There is no need to click on the "dimensions" box before or after you begin drawing
• The "dimensions" box is contextual in nature - expecting a Radius when drawing a circle, a Length when drawing a straight line, Length and Width when drawing a Square and so on

The inner circles are actually cutouts for the mounting holes of this part.

Cutting out the holes involves just two steps:

1. Using the Select Tool, click on one of inner circles - the selected area will change its appearance to a dotted mesh
2. Hit the DELETE key, and the selected area will be "cut out" from the sketch

Repeat this step with the remaining inner circle to create a second cut out.

With these steps, you have created a pair of holes in your part.

Next. Giving the part its shape.

At this point, the mounting holes appear to be in a straight line.

But by drawing a couple of arcs to join the two ends of this part, you can create a perception of these holes being out of line.

Before proceeding to draw an arc, it's important to note that the edge of the circle is not exactly round, but made up of short straight sections to make up the circumference of the circle.

1. To draw an arc, select the 2 Point Arc tool from the menu bar
2. Select a point on the circle on the left and click on it to form the first point of the Arc
3. Drag the mouse over to the circle on the right, and select a point on the edge of this circle
4. Usually the "Tangent at Vertex" hint will indicate that you've correctly located a point on the circle
5. Click on the second point to form the arc
6. The last step would be to pull the arc out by dragging the mouse pointer until you're satisfied with the curvature
7. Alternately, typing in the "Bulge" dimension on your keyboard and releasing the mouse pointer will complete the arc

PROBLEM AREA

• If the arc joins with the circles correctly, then the area bound by the arc should be automatically filled in once you finish drawing
• If the area doesn't fill in, then you haven't properly selected the points on one or both circles when drawing the arc
• If so, delete the arc and repeat the above steps until the area is filled in

NOTE

1. We're focusing only on the visual emphasis of the design - meaning, if the arc is not shaped properly, you can always delete it and repeat the process until you're satisfied with its shape
2. A more realistic design will involve basic measurements before the arc can be drawn to the required shape

The process of drawing the inner arc is similar to the method followed when drawing the outer arc.

Again the process begins by identifying the the starting and ending points of the inner arc along the edges of the two circles

PROBLEM AREA

• When drawing the inner arc, you should be careful about selecting its end points on the circles
• The visuals shows the right and wrong way of selecting the end points of the inner arc
• Doing it the wrong way causes an area of the circle to be cut off as the arc intrudes into the circle
• If the cut off portion is not deleted at this stage it can cause the 3D Model to render incorrectly in your slicer software such a Cura
• Subsequent steps will draw attention to this rendering problem when we are finished with the model

As with outer arc, if the inner arc is drawn correctly, the remaining area of the part bound by this arc will be automatically filled in.

The next step would be to clean up the extra (construction) lines that are not required.

As before, use the Select Tool to click on the inner edges of the two circles and hit DELETE

Removing these two lines fills up the entire area of the part which now appears to be bound by two circles and two arcs.

At this point, you've constructed the 2-dimensional (or 2D) model of the part!

NOTE

• Taking the time to construct the 2D model will save a lot of time and pain when the 3D model is finally constructed
• It's a lot easier to undo mistakes and apply corrections at this stage instead trying to apply corrections once the 3D model is fully constructed
• For example, you may not like the profile of the part when the arcs have been constructed - but deleting them, and redoing them not once, but multiple times is a lot easier at this stage!
  

To convert the part from a 2D sketch into a 3D Model, all you will need to do is pull on the third dimension.

Literally!

For this you will use one of the most intuitive of the tools in the SketchUp toolbox - The Push/Pull Tool

1. Click on the Push/Pull tool from the menu bar and click on the area of the 2D part
2. Click and drag on the mouse in the upward direction
3. The entire 2D structure will form into a 3D model just with a simple click and drag of the mouse!
4. As before, you can drag on the mouse until the model is deep enough before releasing the mouse pointer
5. Alternately, you can type the depth of the model on your keyboard as you drag on the mouse and release the mouse pointer

Once you've completed this step, you will appreciate the time you put in to construct the 2D shape before converting it into a solid 3D model!

The model at this stage in the design process though solid, still looks pretty plain. But with a few more moves, additional characteristics can be added to enhance the functionality of the part.

In this case, I need to position a couple of flat washers when the part is finally mounted to its intended location.

It would be nice to have a couple of recessed areas around the mounting holes to seat the washers so that they don't move around when the part is mounted.

The easiest way to achieve this would be to use the Offset Tool - select this tool from the menu bar.

The Offset tool can make a copy of the shape you select and then either make it larger or smaller around the originally selected shape.

1. To create a recess, click on one of the mounting holes, drag the mouse outward until the circle is large enough to accommodate the washer and release the mouse pointer.
2. Next, switch to the Push/Pull tool and click on the area bound by the newly created "offset" circle
3. This time, instead of pulling on the shape, use this tool to push down on the new circle.
4. Click and drag the mouse down on the screen, to sink the circle into the model to the desired depth to create a recess.
5. You will notice that the "dimension" box on the lower right corner has a negative dimension indicating that you have pushed into the face of the model and created a surface that is lower than the face of the model

If you need a similar recess around the other mounting hole, simply repeat the above steps around the second mounting hole - the last visual shows the part after creating the second recess.

That's it!

Just by employing basic geometric shapes and a little bit of imagination, we've designed and built a functional part ready to be printed!

Although the part looks like a completed model, it's still a "sketch" at this point and is yet to be converted into a "model".

At least in SketchUp, doing this conversion is as easy as exporting the sketch out as a "3D model".

1. From the File menu, click on Export > 3D Model... menu option
2. In the dialog that opens up, type in the name of the model file
3. The file will be saved as a DAE file with a .dae extension

Open up the folder where the file is located and you can see that the DAE file has been created.

If you have MeshLab installed, double clicking on this file will open it up in MeshLab by default

NOTE

• DAE is an industry standard that makes it possible to work with 3D model files in different modelling software.
• Which means that this file originally created in SketchUp can now be opened up in another 3D modelling software such as MeshLab for instance
• If you want to know more about DAE, check out this link

So, why open up the model in MeshLab? The reasons are pretty simple:

1. First, we'll get to know and possibly learn a new tool other than SketchUp
2. Second, MeshLab comes with an extensive set of capabilities to edit, cleanup an improvise on a 3D model
3. Finally, opening up on of my models in MeshLab made me stumble upon a solution to a problem that I was trying to get my head around for at least a couple of days!

PROBLEM AREA

A few steps back, I had emphasized on why it was necessary to correctly select the end-points while drawing an arc. Well, that's because I learned this the very hard way after spending hours on a model that I thought would print, but ended up getting printed with one part of it completely missing!

• If the edges of a model do not merge with adjacent edges correctly, it might end up as a 3D model that is incorrectly rendered
• To the intuitive human-eye the model may look flawless, but you will be left wondering why some parts of the model just won't print
• I first realized this when I opened up one of models in MeshLab as shown in the first visual
• MeshLab clearly indicates the area of the model that it has recognized as complete in solid Black color
• However, a portion of the model that hasn't blended in with the rest of the part showed up in lighter color
• In contrast, the next visual shows a correctly rendered model we created in this IBLE - the entire part appears in single Gray shade
• Stepping back and opening up the original design of the defective model in SketchUp now made it obvious what I missed to notice - SketchUp also indicates this flaw!

LESSON LEARNED

As mentioned in earlier steps, taking the time to correctly construct the 2D sketch can help avoid such pitfalls late in the project.

NOTE

• Using MeshLab, a 3D Model can be cleaned up and designed flaws can be eliminated
• A quick demonstration of how MeshLab can be used can be found on this sourceforge page

I 'm guessing that I've been successful in demonstrating my simple approach to 3D modelling with this IBLE.

As an exercise, you might want to apply this approach to create this simple artifact that represents an alien city.

I have attached the first 12 steps - it took me just over 15 minutes to come up with this design by sticking to these simple rules:

1. Staying with basic shapes - in this case Circles and Lines only!
2. Drawing lines to space the circles apart at equal distances around the center
3. Taking the time to construct the 2D model, and deleting the temporary construction lines using the Select tool
4. Extruding the 2D shape into a 3D model using the Push/Pull tool
5. Using the Offset and Push/Pull tools to repeatedly construct each higher level of the city

Hope you found this IBLE interesting and inspiring enough to venture into an uncharted territory and learn something new.

I know I have! Happy modelling!