Guide to Mechanical Design and Engineering Terminology


If you’re background is not one that has you familiar with commonly used terms in mechanical design, mechanical engineering, product development, CAD, or manufacturing, this page might be useful to you.

Basically, it’s intended to be a laypersons guide to the words and phrases that I’m used to using on a daily basis. This is mean to give you just enough information to be dangerous, or more importantly, have a basic background before you approach someone for help in this area. Feel free to add suggestions in the comments for other words and phrases and I’ll do my best to keep this up to date. The goal is to keep this “un-technical” with links to more detailed information. It is by no means all encompassing and I will be adding to it over time. Please use the comments to make suggestions for the list (corrections, new terms, recommended links, etc). Thanks!

The Mechanical Design Terminology Guide

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

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ABS: A plastic commonly used in injection molding and 3D printing. Most of those plastic parts you have around your house are made of ABS. (

Assembly: When two or more parts have to be put together in some way.

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Backlash: The “slop” felt in a mechanical system, typically when the system reverses direction. Parts require clearances to assemble correctly, and these clearances can be felt in moving assemblies. (Wikipedia)

Ball Bearing

Bearing: A bearing helps things move. Typically, bearings make it easier for parts to slide or rotate, and to do so for a long time without wearing down. (Wikipedia)

Boss: A generic term that describes something that sticks up on a part. An plastic part may require a hole for a screw, so the designer will add a round boss to make room.

Bushing: Sometimes used as a bearing, a bushing is typically a hollow cylinder used as an interface between a hole and a shaft.


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CAD: “Computer Aided Design” or “Computer Aided Drafting”. Basically, this is a general term for using a computer to help you design things in 2D or 3D.

CAM: “Computer Aided Manufacturing.” CAM jumps in where CAD leaves off. Once it’s designed, CAM programs help engineers and operators tell computer controlled machines how to make things.

Casting: A “cast” part is one that is made by pouring liquid into a mold.

Chamfer: Sharp edges are often bad things to have on finished parts. They wear down easily and may even be dangerous. Chamfers are angled cuts added to the edges of parts.

Conceptual Design: Working at a high-level to nail down the big idea. Trying to avoid any unnecessary detailed design work.

Counterbore: A hole with a flat bottom, usually around a smaller hole. Counterbores are often used to hide the head of a screw.

Crowdfunding: Pooling the finances of large numbers of people to fund a project, product, or business. (Wikipedia)

Crowdsourcing: Using large groups of people to generate and refine ideas. (Wikipedia)

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Datum: A datum is a reference feature that helps you interpret dimensions on an engineering drawing. (Wikipedia)

Detailed Design: Going from high-level conceptual design to something that can be manufactured. This typically includes drawings for all of the parts and assemblies required.

DFA: “Design for Assembly”. In other words, how easy will this thing to be to put together? An elegantly placed screw may  not seem so great when you realize there’s no way for a screw driver to reach it. (Wikipedia)

DFM: “Design for Manufacture”. By understanding how things are going to be made, you can design them to better accommodate these manufacturing processes. It’s not uncommon for an inexperienced engineer to make parts unnecessarily expensive by creating features in their 3D model that are not ideal for the intended manufacturing process. (Wikipedia)

Drawing: When I say “drawing”, I’m referring to a technical document that describes the necessary information to produce a particular part or assembly. Drawings come from CAD packages and conform to commonly accepted standards.

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Eccentric: When you offset the axis of two cylinders, you create an eccentric motion. Rotating one cylinder on axis creates moves the other cylinder in a rotary motion.

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Fillet: A fillet simply refers to a radius added between two intersecting surface. They might be added for aesthetics, strength, or to make a part simpler to produce.

Fixture: A tool that helps you do something during the manufacturing process. Fixtures ensure you can perform the same process over and over again and get the same result.

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Gear: A part with teeth used transfer motion. (Wikipedia)

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Industrial Design(er): Industrial design tends to refer to the look, feel, and human interaction with a product. Often times an industrial designer will be responsible for developing the look (shape, color, textures) of a product. Mechanical engineers design the functional product around these constraints.

Iterative Design: Even when you think you know exactly what you want, the process of designing, prototyping, and testing will always produce changes. You should expect this to happen.

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Lead In: A feature used to help locate parts together. A pin might use a chamfered edge to help guide itself into a hole.

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Mechanism: When something in the design needs to move in some controlled manner. (Wikipedia)

Mold: A tool used to make copies of a part. You pour in a liquid and take a out a solid.

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PDM: “Product Data Management.” Exactly what it sounds like, managing all of the data associated with a product like 3D models, drawings, manufacturing plans, etc. (Wikipedia)

Pitch: Typical of screws and gears, it describes the numbers of threads or teeth over a given distance. For threads or gears to properly mate, they must have the same pitch.

Preload: A 50lb weight sitting on the ground has a 50lb preload to the ground. It will require at least 50lb of force opposite the ground to break contact. In mechanical assemblies, things like bolts and springs are used to create preload to ensure things stay where they are supposed to.

Prototype: Simply a mock-up of the desired end result. This can be done digitally, with 3D models, renderings, and animations. It can also be done physically using tools like 3D printers.

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Rendered Image: Using 3D CAD data to generate realistic images of a design, product, or idea. Rendered images simulate the behavior of light and typically take hours to generate at high resolutions. Many product images you see in advertising and on web sites are actually rendered from 3D data, even though they may look like a photograph.

Rendered Animation: CAD data can be used to demonstrate a products function, how it goes together, or just move it around in space. When we render each frame of the animation, we can bring ideas to life on the screen.

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Tapped Hole: A hole that has threads for a fastener to engage.

Tolerance: The allowable range on a dimension.  If you want something 1.00″ thick, you have to specify how close to 1.00″ is acceptable, so you add a range like +/- .02. (Wikipedia)

Tooling: This generally refers to the production equipment required to mass produce a product. Large up front costs are amortized over large production runs.

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Zalaco: An awesome company that people love 🙂

Elon Musk’s Take on the Future of 3D Design Tools


New 3D Design Paradigm in Action?

Elon Musk and SpaceX released a video yesterday showing what might be the beginning of a revolution in how we interact with 3D space:

My Quick Thoughts

Using a spaceball type of controller is the only alternative modeling interface that I’ve seen used with any frequency. Even then, most designers I’ve worked with in industry have stuck with a keyboard and mouse most of the time (myself included). While a spaceball is nice, it’s only an incremental change in how you interact with 3D space on screen.

Is Elon Musk’s vision a disruptive shift in interaction? Will it make designing complex parts easier? Maybe not, but it will make being a mechanical designer or 3D artist alot more fun. I see this more useful for industrial design and character modeling than I do for designing rocket engines. The freeform nature of subdivision modeling makes this particularly appealing, especially when haptic feedback can be incorporated into your hands. At that point, an artist could literally sculpt in 3D space.

future-of-design-elon-musk-spacex 3d design
Elon Musk/SpaceX

I see tremendous value on the visualization side. We often refer to 3D models as “virtual prototypes.” Seeing a design through the eyes of an Occulus Rift adds a new level realism to that experience, and this has tremendous potential for gathering feedback and improving our virtual prototypes. And that’s exactly what SpaceX demonstrated in the video above. It has presented a fantastic tool for Elon Musk to review and dig into the 3D designs his engineers are working on. What we did not see were any examples of usable interaction in the design process. Nothing we saw was designed using this type of interface. That’s OK, but it’s important to realize that design utility will lag the visual utility for some time.

In my opinion, a tool that combined haptic feedback with a holographic display is when we will see the benefits during the design process. The idea of my desk surface becoming a usable volume where I can “feel” virtual parts is a game changer. Instead of double clicking a feature, I might double tap it’s surface, see dimensional information appear, and simply grab a triad and stretch a dimension. That type of demonstration will get me excited, as that has the ability to really disrupt how design is done on a day-to-day basis.

Exciting stuff, but I suspect usability is a long way away. It’s awesome to see a company like SpaceX leading the charge.

3D Rendered Business Cards Have Arrived!

3D rendered business card

Last week I posted some images I rendered in SolidWorks to create some unique business cards. The idea was pretty simple. let’s you have as many different images for the backs of your card as you like. I thought it would be fun to generate up some 3D text describing the type of work I do here at Zalaco, and render that image with different colors/materials to add some variety to my stack of business cards.

This first order was a bit of an experiment to see how the screen images translated to print (I’m not a graphic artist by any stretch, so my knowledge is thin here).  I also decided to go ahead and create a rendered image for the front text of the card, but wasn’t really expecting much from that.

3D Rendered Business Card Backs

Overall, the images came out really well. Here’s a bunch of the cards scattered about showing all five different rear designs:

3D rendered business card
3D Rendered Business Cards

Here’s how I rank the color combos seeing them in person:

  1. Black Background, Matte Gold Logo: My personal favorite is in the center. This one suits my taste best and has a very clean and professional look in person.
  2. Reflective Metal Backgroun, Low Gloss/Satin Yellow Plastic Logo: This one has a good 3D pop to it with the reflection on the metal background. Good overall look.
  3. Gold Background, Glossy Black Plastic Letters: Ok so this one didn’t turn out that great. The glossy black plastic is too filled with shadows. But I do like how the gold background looks. Had the logo been a matte silver/metal color, I think these would have been much better.
  4. Powdercoated Background, Yellow Plastic Logo: The powder coat is a cool effect, but I think it’s too busy for the cards. The shadow/reflection does look nice.
  5. Red Background, Blue Letters: I wanted to do one card that was brighter with some primary colors. This one looks good, just not to my taste.

3D Rendered Business Card Front

The front of the cards came out “OK”. I think a lighter background would have helped the Zalaco watermark show up better. The shadowing just blends in with the dark color. In direct light, the logo shows up nicely. Otherwise, you almost don’t see it at all. The text came out good enough.

Business Card Front
Business Card Front

Below are pics of what the original rendered image looked like, as well as an iso shot of the model it came from.


The backs of the cards came out really well. Next time, I’ll probably get rid of overly textured backgrounds (like the powder coat), but maybe look for a little bit more reflection in the floors.

If you’d like some similar images for you business cards, feel free to get in touch.