Initial Thoughts on Fusion 360

Published in CAD

Autodesk's Fusion 360 product is a unique CAD platform that I've been using for a few weeks. There are significant, fundamental differences compared to traditional CAD applications such as SolidWorks. After spending some time with it I will discuss some of my observations and comments on the product so far.

Philisophy

Parts and Assembly

The main difference you will encounter when transitioning to Fusion360 is in its modeling philosophy. In traditional CAD, parts exist in their own file, and have their own history, properties, parameters, and so on. These are then added and combined to form assemblies. Of course, there are assembly-driven design approaches in traditional CAD however each created part is still "containerized" and can still be opened and edited independently.

In Fusion 360, there is no concept of part or assembly by rather by simply a design file. Each file you start has the ability to be either a part or an assembly. What triggers this is whether or not there are components in it. The component in Fusion 360 is analagous the part in traditional CAD. The main difference, however, is that the component in Fusion 360 shares its feature history with any and all other features in the file (discussed more below).

A fusion 360 design file containing only bodies at the top-level will look and act much like a multi-body part in SolidWorks. As soon as one of these bodies is put into a component, or a new component created, does it behave like an assembly, in which motion is enabled and parts can move if unrestrained.

Timeline

Because parts are typically designed as components within the context of the overall (assembly) file, the feature history - or timeline in Fusion 360 - is unified across all parts and features. This represents another sigificant difference, because things like mates will show up in the feature history, which only exist at the assembly level in traditional CAD and not in a history-centric manner. This can be confusing and seem like a downside, since if you want to work on an individual part you cannot actually isolate the part and its features as you would typically expect (though you can automatically hide other features not associated with a component but it is merely a show/hide operation). The timeline, therefore, represents each step taken to produce the design - including any non-modeling operations such as move commands, joints, and ground/unground.

Complaints

In building some projects I've encountered a number of areas that I think could be improved:

The measure tool is underdeveloped.

Compared to the measuring tool in SolidWorks or SolidEdge, the measure tool lacks features found in those programs. There are three features in SolidWorks that are powerful:

  • When you click on a circular or cylindrical reference, you have the ability to measure from the inside, center, or outside (or min, center, max) for the geometry. This is a common occurence and is very useful with non-planar geometries.
  • Point-to-point measuring, in which wherever you click, a point is placed on the surface and the measurement is made from there, and does not snap to a center or edge

Fusion360 has neither of these and only reports a single distance. There is the option for "Show snap points", which allows the selection of the center of circular arcs and endpoints.

Versions are created on each save.

This one is not necessarily bad but I think if tweaked it would be great. By default, a version for your document ('V1", "V2", etc.) is made every time you save. While having a whole record of all of your work is useful, it might be better if it operated more like version control (git), where you have the option to make milestone records, since in normal work you save often to prevent data loss, rather than for recording the state of your design. This results in a large number of "versions". In git, you make changes and save as you please. Then, when your files are in a good state, your "commit" them to version control. The available states are only those you "commit". In Fusion 360 you have access to every save, which is fine and in many very cases useful; but perhaps if the option to hide "working" type saves and similarly mark "milesone" type saves was added it might be a much better workflow.

Also, a version is created for any change, even show/hide type changes. For example, if you insert a part/design into another design, but the planes are visible, you cannot hide them from the parent file because you cannot edit the inserted part there. Instead you must open the inserted file, hide the planes, and SAVE A NEW VERSION.

Is a managed application.

By managed I am refering to the data. Fusion 360 is a cloud-based application and all of your files are stored in the cloud on Autodesk's servers. Because it does not allow the option for local work I see this as a downside. Cloud-based work offers two great features in 1) your data is accessible from anywhere, and 2) it is backed up. Both of these I enjoy but the fact that you are forced into cloud-only is a drawback. And for some companies and industries this would likely prevent them from using the application due to the nature of work and requirements for data privacy.

This also sometimes results in issuse with file management. Because it tracks your files and the references, if a file is linked in another file (i.e. you insert a part into another file) you cannot delete the linked file. Makes sense but even if you delete the linked file from the parent file and save a new version, you still cannot delete the linked file because a previous version of the design still references the linked file. This is annoying because I like to clean up my project folders and delete unused files. You cannot delete previous versions and the only workaround is to save a copy of the parent file as a new design. Not ideal.

No part configurations.

SolidWorks has a great feature for their parts called configurations, which allows a single part file to have several "versions" wherein properties are changed in each resulting in different versions, typically dimensions resulting in different sized parts. This allows you to create a part and then subsequently create all the different versions of it, having the benefit of not duplicating work (DRY in the software community).

Joints are not listed within each component.

Makes sense considering these are not features added to the respective components but to the top-level design, however it makes it difficult to find the joint associated for a particular component, especially if there are many joints. The only feature to find them is through the right click menu on a component, there is a "Select referencing Joints" command which highlights the joints associated with that component. Useful, but is an extra step and click that I would not like to have to do.

Pricing is subscription based.

For shops and engineering houses that are interested in purchasing a permanent license for the software, this is not an option.

No weld symbols in drawings.

2D drawing capability is included and can be made for an individual component or the design overall. There are all of the basic and common operations included, but not the option for weld symbols.

Mass properties are reported in ouncemass when inch is used.

When the file uses inch units, mass properties are listed in ouncemass and not lb.

Pros

There are a number of unique and useful elements in Fusion360 that make it attractive:

Flexible modeling.

Out of the box Fusion 360 supports modeling using/with:

  • traditional parametric solid modeling
  • direct solid modeling
  • surfacing
  • subdivision (T-splines)
  • mesh editing

Additionally, there is support for sheet metal modeling.

Subdivision modeling is a method found in graphics-related 3D CAD packages such as modo, 3D Studio Max, and Maya, and is a different modeling method compared to solid modeling found in engineering CAD. Though its use in engineering modeling may be limited, in certain instances and designs it is useful and it is nice to have there in case you need to use it.

Integrated Design Tools.

Also out of the box are integrated FEA, CAM, and generative design tools. As an analyst I typically have low regard for integrated FEA tools found in CAD packages as they are very feature limited and typically have poor meshing capabilities, only allowing for tetrahedral meshing. However, Fusion 360 does and can mesh with higher order elements which will improve simulation accuracy. There may be ways to obtain adequate results in Fusion 360 FEA and in a future post I will discuss some analysis best practices.

The CAM integration is a great feature since this is typically an added expense that must be undertaken if you do machining. Additionally, generative design is an interesting feature that I have yet to explore but may be useful. However, after some cursory investigation, it appears that paid cloud credits are needed in order to compute the designs using Autodesk's servers, which is not ideal since for this feature you would have to pay extra to use it.

Is cloud managed.

Yes, I listed this as a con above, but there is no doubt that it is convenient. I can work on a project on my desktop computer and then switch to my laptop and resume where I left off. This is a feature we have become accustomed to today since many services are web-based and offer this functionality (Google docs, Evernote, etc.)

Pricing is subscription based.

Yes, this was also listed as a con. However, this is a plus because it reduces the total cost to obtain the software and makes it more affordable.

Summary and Conclusions

While the initial list of cons is longer the the list of pros, Fusion 360 is a functional application that is attractive because it offers much for a relatively low price point. It is subscription based and costs $495 per year or $60 per month. Another CAD application with integrated FEA and a CAM plugin would likely cost $10k+, and therefore the breakeven point with Fusion360 would be approximately 20 years. Over that timespan software would be updated numerous times and thus you would need to be on maintenance or purchase a new licence anyway. Thus there is good value with Fusion360 that should be considered.

And as a quick summary:

  • has a different design philisophy which takes getting used to for traditonal CAD users
  • the modeling features are good
  • the integrated FEA is integrated FEA, which is to say, poor to ok
  • (while I have  not used it yet,) the integrated CAM looks good
  • file type I/O is good, can open CATIA V5
  • drawings capabilty leaves some to be desired
  • small features need improvement (e.g. the measure tool, mass properties dialog)