FAQ - Computer Aided Design (CAD)

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Richard Hull
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FAQ - Computer Aided Design (CAD)

Post by Richard Hull » Thu Feb 23, 2017 8:49 am

R.Hull transfer to FAQs by request

postby Andrew Robinson » Wed Feb 22, 2017 10:50 am

The purpose of this FAQ is to outline some of the benefits and drawbacks of CAD/CAM (Computer Aided Design/Computer Aided Machining). It’s true that not everyone here will have access to the latest and greatest software options out there, or the skills and equipment necessary to fully utilize this software, however, this should not dissuade or discourage anyone from continuing to read on. There are many grades of CAD software out there, and several can be found for free, and while you traditionally will pair higher end CAD and CAM suites together, this is not exclusively true, nor is it a requirement. There are in fact several benefits to using a standalone CAD application and I highly recommend anyone out there with aspirations of building a more complex fusor to consider going the virtual route first with regard to their design. There are several advantages to doing so which we will discuss in detail below.

To start off, let’s answer the first question most of you have. Why should I bother modeling everything in CAD first when I can just build it now? The biggest answer to this question is cost savings due to design errors. There are countless examples on these forums of people rushing into things and making mistakes that end up being unsurprisingly costly. Such examples include bolt misplacement, incorrect welds, clearance issues, thermal issues, etc. The list can go on and on. The benefits of using CAD far outweigh the cons:

1. Allows you to visualize your assembly beforehand.
2. Check for clearance issues before committing in construction
3. Ability to use finite element analysis to simulate thermal, mechanical, electromagnetic, fluid, etc. working elements.
4. Enables more accurate BOM (Build of Material) creation for the purpose of purchasing logistics.
5. Greatly improves the quality of the design as a whole.
6. Improves communication between third parties.
7. Revision work is more efficient.
8. The list goes on…

Also, at the time of this writing, CAD is now a fairly standardized practice across most engineering disciplines and as a result, most of the parts you will need for your fusor probably already exist virtually in a format you can consume. If you look long enough on most vendor websites, you will eventually find a CAD library. In the library, you will usually find 90-95% of their products as a convenient download in one of the common formats such as .part or .step. If nothing else, I strongly recommend that everyone here at least invest some time in designing their chamber using CAD. By the time you are finished, you will understand the benefits yourself.

Aside from the benefits mentioned above, there is one additional somewhat overlooked benefit to first designing with CAD. As I already mentioned, most people rush into construction or blow through a chunk of their budget without the full picture in mind. This usually results in a lot of wasted time, money, and energy. CAD has the happy side effect of slowing down the build process which gives you extra time to approach problems critically. This also gives you some additional foresight which at the end of day saves you money.

CAD also enables us to visualize instead of conceptualize 3D space. What seems like a great idea in your head, may not be realistic or ideal in the real world. A perfect example are some older sedans that pack so many things tightly under the hood of the car that you practically have to disassemble the engine to change the battery. Sure the battery fit in the available volume, however, no one bothered to test how that battery would be removed from the chassis post assembly. In some instances, the battery cannot physically contort in such a way required for removal. Don’t box yourself into a similar situation. Use the motion and assembly capabilities of your CAD software and make sure that your assemblies mechanically make sense!

If you are able to acquire a higher end engineering software package such as Solidworks, then I highly recommend you dig into FEA as well. For some of the more complex fusor projects these resources are invaluable! Several of you out there are still students. Inquire with your teachers or professors about your schools software licensing. For those of you attending a University, especially those with engineering schools, you will most definitely have access to Solidworks. Check out the book store or some of the engineering labs on campus. Even some community colleges may have access. In fact, some community colleges will even teach introductory Solidworks courses which will include a student license with tuition. Outside of Solidworks, there are several other direct industry competitors and other less popular options. I recommend doing some research and finding the solution that is best for your budget. You might even look into getting started with Google SketchUp just to get your feet wet. Regardless of how you decide to go about it, just decide to commit to it. I cannot begin to tell you how much money I have saved professionally in the long run by utilizing CAD first. Do yourself a favor and take the plunge.

Watch this entire video (below) and you will see a pretty good collection of the simulation capabilities available in Solidworks. For additional examples related to fusors specifically, check out historical posts of mine too. I usually always include a CAD model with real pictures of the components being represented.

https://www.youtube.com/watch?v=YyBFYs733uM

Best of luck!

~Andrew Robinson
I can wire anything directly into anything! I'm the professor!
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

ian_krase
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Re: FAQ - Computer Aided Design (CAD)

Post by ian_krase » Thu Feb 23, 2017 9:13 am

It should be noted that both Onshape and Autodesk Inventor 360 provide cloud-based parametric CAD that's free to use without paying any money. (Onshape sharply limits your ability to make private models, Inventor 360 is usable by hobbyists and by startup companies that don't have much income yet.) I've used both of these; Onshape seemed more than a little cumbersome but still very useful.

If you are a university student you can almost certainly get an academic license for all of Autodesk's products (including their much more full-featured non-360 Inventor) with minimal limitations. Last I checked you still had to pay for Solidworks education licenses but not too much.

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Andrew Robinson
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Re: FAQ - Computer Aided Design (CAD)

Post by Andrew Robinson » Sat Mar 11, 2017 10:50 pm

Another page/video that I should have added to my original FAQ above: http://www.solidworks.com/sw/products/3 ... -check.htm
I can wire anything directly into anything! I'm the professor!

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