Designing Mechs in SketchUp: Part 1

Jessica TC Lee shares her expertise in SketchUp and mech design...

In this tutorial, we will learn how to complete a portfolio piece of a mech design in SketchUp, KeyShot and Photoshop. We'll talk about the process of designing the mech, developing thumbnails into a detailed sketch. You'll be introduced to essential SketchUp plugin tools needed for following the tutorial, examples of how to use them, important modeling tricks and demonstrations of how to achieve certain shape results. In the next article, we'll take the completed model into KeyShot to add materials, make a render, and then finish the image in Photoshop using basic photo-compositing techniques.

Before I even start making thumbnails, I usually research online for inspiration, especially when I don't have a specific idea in mind. I look into references that have a lot of mechanical parts. I sometimes just draw from references to build an almost subconscious awareness of how the mechanical parts distribute, and are concealed and exposed. To name a few good references: DARPA robots and drones, car assembly machines, sand buggies, garden machinery, generators, street-cleaning machines, and so on.

I also pay attention to where the power source might be located and how big it has to be to move the machine, and what elements such vents, wires, hydraulics, rivets, joints, handles and sensors look like and where they're located. Collecting this information is like preparing all the carving tools and materials when sculpting. I know where to put what, so the design not only looks cool but makes sense, without me having to stop too often from the creative process to go back to look up things that I might be able to use.

Step 01 Thumbnails

The point of thumbnailing is to figure out an interesting and exciting silhouette which will define the general shape of the final design. Since we are designing something mechanical, there are a few things we should ask when doing thumbnails. Is this mech bipedal or quadrupedal? How does it move? Does it use weapons? What is it for?

These basic questions define how the 'big chunks' of the silhouettes are arranged and proportioned. When I am doing mine, I like to think about if it's an attack mech; where the weapons might go and what kind of weapons they are; I like to think about how the 'head', 'body' and 'legs' would co-ordinate in order for the mech to move. Try to think about the mech in motion to get a better grasp on the overall arrangement and proportion of all the parts. A useful tip to keep in mind is the common rule for proportioning the overall look of the parts. I always have big, middle-sized, and small parts. As my mentor told me, treat it like the proportion of the layers of a cake. The final touch will be the tiny cherry decorations! In a mech design, the 'cherries' can be lights, rivets, pipes, wires or handles.

Testing out design ideas with thumbnails

Step 02: Detailed sketch

After I finish the thumbnails, I move on to interpret the chosen one as a perspective drawing. The method I use allows me to gradually flesh out all the details with 'layered thinking'.

In #1, I rough out the general shape of the design in perspective and some ideas of the overall structure. In order to translate the design from the thumbnails, I think about the 'big chunks' in perspective, such as the big rectangular shape on its back. I also mirror the legs.

I pay attention to how the joints are connected and use circles to indicate them. I also roughly think about how I'd like the 'head' or the front part of the mech to look, since it will be the focal point of the design.

In #2, I further define and develop the look of the big parts and important joints, such as subdividing or cutting out the shapes and editing cut lines. I also start to think about the decorative 'cherry' parts, such as where to put handles, wires and rivets.

In #3 and #4, I use a new paper and start to really define all the details. After I am satisfied, I add some basic shadow to see how the overall shapes will feel in 3D. For the mechanisms of the joints, aside from following the thumbnails, I sometimes experiment with ideas by drawing simple cylinders and boxes to see what other possibilities are.

Developing our chosen thumbnail into something more complete

Step 03: Important SketchUp plugins and customized interface

I'd like to mention a few necessary plugins for accomplishing this tutorial. All the plugins I mention can be found on SketchUcation, a free online SketchUp plugin community.

I install their Plugin Store tool so I can easily find and directly install plugins to SketchUp without having to go through the process of manually installing and downloading them from the web. The SketchUcation Plugin Store tool can now be found under the Extensions tab. The essential plugins for this tutorial are FredoScale, JointPushPull, Round Corner, and BoolTools.

All the above plugins are free except for BoolTools, which is released by smustard.com and costs ten bucks. However, it's worth having.

After installing all the essential plugins, it's time to customize the interface by going to View > Toolbars. Except for the above-mentioned plugins, I usually also turn on Shadows, Measurements, Construction, Drawing, Solid Tools, Styles, Views, and Warehouse.

Since I like to model in Parallel Projection mode (found under the Camera tab), it's convenient to have the Views tool on, so I can change to different views to check my design. Having the Styles tool on is handy too, because sometimes I need to adjust geometries or components that are hidden. With the Styles tool on, I can switch between shaded mode and X-Ray mode.

In addition, since I use SketchUp Make instead of SketchUp Pro, I can't export models to OBJ files with the default options, so I get SketchUcation's OBJ Exporter plugin in order to do so.

Some useful plugins recommended for this tutorial

Step 04: Blocking in

I start to block in the big chunks of the design. I overlook all the details or subdivided shapes at this point and just try to get the proportion of the design the way I want. I save a cube and a cylinder to my component library (fig.04b) so I can simply drag them into the scene, scale and rotate them for blocking in. This way, the work process will be much faster and easier, and the components won't 'stick' to each other (if the geometries are not components or in groups, SketchUp automatically merges any connected parts). I carve out the big general shape of the head part, which is the focal point, to get a good feeling of how the overall silhouette of the model would look. I mimic what other 3D programs have and make components on both sides by flipping one side to mirror it on the other.

After finishing the initial blocking-in, I make the cubes and cylinders 'unique' in order to further detail the shapes of the different parts without changing the shapes of the others (fig.04c). This is a very important action that I need to constantly remember to do. Without it, if I modify one component, I would then affect the other components which are recognized by SketchUp as being its duplicates.

Fig.4a - The basic block-out of the mech design

Fig.4b - Saving shapes to your component library will save time later

Fig.4c - Don't forget to make shapes 'unique' as you go along!

Step 05: Starting to add details

After establishing the general proportion and shapes, I start to dig into the focal point, which is the head and front area. At this point, I still don't get too detailed with tiny rivets or handles, but pay more attention to the subdivided shapes of each big chunk. The advantage of making different parts into components comes in again, because I can still easily modify each part, even when it is hidden by other parts, by duplicating it and dragging it to an empty area and modifying on the duplicate (fig.05b).

I use the Tapering tool in the FredoScale plugin to make a component slant without messing up the geometries (fig.05c). The same tool can be used to taper a component as the name says (fig.05d). The power of the FredoScale plugin is to modify the general shape of a selected area without messing up with the geometries, in most cases, and can achieve results very fast.

Fig.5a - Adding more detail to key areas

Fig.5b - Duplicating a piece and moving it out for ease of editing

Fig.5c - Using FredoScale to make slanted areas

Fig.5d - Using FredoScale's Tapering tool

Step 06: Adding further details

I also use the technique of intersecting faces to carve out certain shapes while not messing up the geometry of the component. I first put in the shape of the part that I want to cut out from the shape that is in the component. I then select them all and right-click to find the Intersect Faces option. I choose 'with Selection' to cut the geometries. However, since I am editing inside the component, it doesn't really matter which option I choose. They will all do the same thing. However, if I am editing outside a component, then the result will be only the cut lines of the intersecting components instead of really cutting the geometries (fig.06a). I then remove the part that I don't want and seal the geometry (fig.06b).

A way of cutting geometries outside of components or groups is by using the BoolTools plugin. Here I use the Difference tool to cut out the shape I don't want (fig.06c). The icons of the BoolTool clearly show the function of each subtool. After getting to a certain degree of detailing, I change to a side view to make sure that the upper-front part of the mech won't cut into the parts on the sides when it's turning around (fig.06d).

Fig.6a - Cutting up some geometry

Fig.6b - Removing unwanted geometry

Fig.6c - Cutting geometry with BoolTools

Fig.6d - Checking how the mech looks in profile

Step 07: Creating handles and arched panels

This step is more about showing a couple of tricks and techniques that help me get certain shapes that I want. For creating handles, I first draw a circle, then find its center and draw the path along which I want my handle to follow, and then use the Follow Me tool to finish the tube (fig.07b). I finish the handle in an empty area so I can see better, then make it a component before bringing it back to the model. All the wires, handles, tubes and pipes can be achieved using this technique.

Sometimes I want a covering panel slightly above the body but with exactly the same arch or shape. In order to achieve that, I first duplicate the face which has the arch I want, and elongate it (fig.07c). After that, the powerful plugin JointPushPull comes in to help me thicken the surface. It allows me to push/pull a surface that is not flat (fig.07d).

However, I decide to tweak the shape a little bit, again using the Tapering tool in FredoScale. I want the axes to follow the slant degree of the panel, so I click on an edge that has a similar slant degree to redefine the scaling axes (fig.07e).

Fig.7a - Adding handle and arch details to the mech

Fig.7b - Creating handles with the Follow Me tool

Fig.7c - Duplicating and enlarging an existing face to create the arch piece

Fig.7d - Using the JointPushPull plugin to thicken the arch

Fig.7e - Adjusting the scaling axes of a slanted piece

Step 08: Further detailing and mechanism logic

I further detail the front part and the middle body with other techniques. Here I use the Arch tool to connect arches with different degrees to create the result I want (fig.08b). Here I also use a technique to create the thickness of certain portions of a handle. I first use the Intersect tool to create cut lines, and then use JointPushPull to create the thickness. (fig.08c)

I also want to create an indentation on a slanted surface with the same slanting degree. I first use the Follow Me tool to create the indentation (fig.08d). I then use the Intersect Faces tool to cut the geometries and delete any unwanted bits that I don't want (fig.08e).

An important thing to keep in mind when interpreting a 2D mech design into a 3D model is how different parts are connected, and if they can move without cutting into each other. When I design and model, I mentally assign certain parts to certain groups, such as the 'thigh' group, the 'joint' group and the 'leg' group, to make sure that they're connected in a way that can move, no matter how complex the structures are. Once things are broken down into different groups, I know that I can pay more attention to how to make the 'joint' groups functional and have more fun with the shapes of the other parts.

Fig.8a - Taking the details even further

Fig.8b - Connecting arches with the Arch tool

Fig.8c - JointPushPull in action again

Fig.8d - Creating indentations with the Follow Me tool

Fig.8e - Cutting and deleting unwanted geometry

Step 09: Hidden joints

After finishing most parts of the front portion of the mech, I start to think about the joints between the main body and the front legs. These joints are hidden from a three-quarter view beauty shot, but are essential to the mechanism of the front legs.

I block in some cylinders and boxes to settle the mechanism, which should allow the legs to move both up and down, left and right. Then I detail the shapes of the parts to make them more than just primary shapes (fig.09a). A small trick I use here to get a bevel corner on an irregular shape is by using the Intersection Faces tool and sealing the holes later (fig.09b).

Fig.9a - Modeling more detailed joints

Fig.9b - Using Intersection Faces to add bevel detail

Step 10: Back legs

It's time to get to the back legs. There is a lot of fine tweaking to the model and I don't follow exactly how the original sketch looks, especially with the ankle parts. I rearrange how the panels are overlapping each other, so I can get a look as close to the sketch as possible while not making the legs too thin and narrow. This is a situation I often encounter when interpreting 2D design to 3D; the width of a part of a sketch on paper is often not really the same case when it's modeled.

I adjust the proportion of the back legs because I imagine this mech has a strong jumping mechanism that resembles a hunting animal. I start to have a rough idea about the exact usage of this mech; more for scouting in a small area. In many cases, a design that mimics a function in nature is usually appealing because of its relatability.

The mech's detail level at this stage

Step 11: Back legs, continued

I use a couple of tricks to get certain shapes. For the small panel extruding from the joints, I first draw a rectangle, and then cut out the shape on the rectangle (fig.11a). I finish the panel by pushing out the thickness.

I also want to create an offset continuation on an irregular and slanted surface. Therefore, I first use the Offset tool to offset the edges I want, and then I draw the construction lines from the points. In order to connect the construction lines, I draw along the line I already have and find the pink indicating line, which means the new portion of the line is on the same path. Eventually, I connect all the points and create faces (fig.11b).

Fig.11a - The mech's detail level at this stage

Fig.11b - Top to bottom: drawing construction lines, finding the pink line, and connecting the points to create faces

Step 12: Wrapping up details

Here I like to mention a few tricks and a plugin that are useful for adding the 'cherries' on top, or the details such as rivets, small and repetitive indentations, bevels on an irregular shape, and smooth bevels on edges. I created and saved a rivet to my component library right at the beginning, so now I simply drag and drop it every time I need it.

To create repetitive indentations with the same intervals, I first draw the shape of the first indentation, and then duplicate it by holding Ctrl while using the Move tool. Right after duplication, I type in '3/' to create two duplicates in between (fig.12b). '3/' means 'divide the interval by three'.

We can also duplicate right next to the original and type in '3X', which means 'make three duplicates from the original'. I then finish the indentation by using the Push/Pull tool.

Fig.12a - The mech's detail level at this stage

Fig.12b - Duplicating a piece to create repeating patterns

Step 13: Refining edges with bevels

To create a bevel on an irregular surface, instead of using 'Follow Me' as if it was on a straight edge, I use the 'Intersection Faces' tool (fig.13a).

The plugin I use to create smooth and sophisticated narrow bevels on edges is called RoundCorner. It is simply for mimicking how, in reality, most edges of an object are not really that sharp (fig.13b).

Finally, it's time to check if the four legs can move without obstruction, and can allow the mech a reasonably smooth movement and ability to turn (fig.13c). Next time, we'll look at ID-labeling, adding materials and rendering with KeyShot, and creating a background to finish the image!

Fig.13a - Creating bevel edge detail with Intersection Faces

Fig.13b - Creating smoother bevels with RoundCorner

Fig.13c - Testing whether the limbs can move unobstructed

Related links

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