CAD for Hobbyists: Onshape

Onshape - Web Based CAD
Onshape – Web Based CAD

Onshape is the first sketch/feature based modeler we are looking at in this series.  To create a part, you create a 2D sketch to define a feature.  Subsequent features are then built on top of one another.  This is the same modeling paradigm that is used by many professional CAD programs (Solidworks, Inventor).  The thing that really sets Onshape apart from these programs is the fact that it is completely web-based.

Yes you read that correctly, Onshape is 100% on the web.  You don’t have to install anything to run it, no browser extensions to download.  The only thing you need is a relatively modern web-browser (I’ve used it in both Chrome and Firefox without any hiccups).  On top of that, Onshape has companion apps (both Android and iOS) that provide full CAD modelling access.

Onshape is perhaps the newest player on the CAD scene, aiming themselves as a more flexible replacement for more conventional approaches such as Solidworks, Inventor, or even Fusion 360 (which we will take an in depth look at in our next post in the series).  The fact that it is a website means it is constantly getting updates that are seamless to the end-user, there aren’t any services packs or updates to download.

Another feature that really sets Onshape apart from the last two CAD programs we looked at is the ability to create model assemblies.  The ability to create assemblies is an extremely useful feature as it lets you see how multiple components are going to fit together in a finished component.  This is extremely useful to hobbyists who are typically integrating multiple parts together into a unified assembly.

Sample Project

To create a new part in Onshape, you create a new Part Studio.  A part studio is a hybrid between a normal part and an assembly, you can design individual parts in the part studio or design multiple parts together at the same time as part of an assembly  (this is called a multi-body part).  Onshape has a specific file type for true assembly into which you can import a multi-body part.   A blank part studio presents an empty space displaying the 3 primary work planes (front, right, top).

User Interface
User Interface

To start the bottle opener design, we are going to create a sketch on the right plane.  I like to build models that are oriented in the same way they would be in the real world.

Creating A Sketch
Creating A Sketch

With a new blank sketch created, we use the view cube widget to look straight on at the sketch.  The view cube is located in the upper right corner of the user interface.

Rotating Part using View Cube
Rotating Part using View Cube

The next step is to create a rectangle to be  the body of the bottle opener.  We will use the center point rectangle as it lets you center it on any point (in this case, the origin).

Creating a sketch rectangle
Creating a sketch rectangle

The exact size of the rectangle doesn’t matter at this point, we will define its exact size using the dimension tool

Rectangle sketched
Rectangle sketched
The dimension Tool
The dimension Tool

You can launch the dimension tool using the menu or the hotkey (d).  With the dimension tool select click the item which you would like to dimension.  Items that are properly dimension, and fully defined, turn black in the interface.

Rectangle properly dimensioned.
Rectangle properly dimensioned.

With the sketch fully defined, we can then use the extrude tool to create the bottle opener body.  I like to use the symmetric option when doing extrudes to keep the model centered on the origin.

Extruding the bottle opener body
Extruding the bottle opener body

With the extrude created, we can then create a new sketch to define the next feature.  To create a new sketch, we click the sketch button and then select the plane on which we would like to sketch.

Creating a new sketh
Creating a new sketch

With the new sketch created on the side of the bottle opener we can start sketching the shape of the bottle opener opening.  As we are sketching, the lines will attempt to snap to relationships that could exist within the model.  For example, if we sketch a line perpendicular to another, it will try to snap the new line to be perpendicular and add a perpendicular relationship.  Again, we do not need to have everything perfect with either the position or shape of the feature we are trying to create.  We can add additional relationships and dimensions to fully define the sketch.

Sketching the opening.
Sketching the opening.

In addition to adding dimensions, we will use the coincident relationship to snap end points of a line to the corner of the bottle opener body.

Using the coincident relation.
Using the coincident relation.
Sketch complete.
Sketch complete.

With the bottle opener opening sketch complete, we will use the extrude feature again, this time selecting the remove material option.  This allows us to cut out the bottle opener opening.

Cutting out the opening
Cutting out the opening

We will next cut out the keyring hole.  We could sketch and position a hole of the appropriate size and use the extrude feature, but instead we will simply sketch where the center point of the keyring hole will be located.

Sketch for the keyring hole location
Sketch for the keyring hole location

With the center point of the keyring hole sketched we will then use the hole feature to create the keyring hole cutout.  The hole feature allows us to define a hole by diameter and depth at a selected center point location.

Hole Tool
Hole Tool

With the hole created, we will use the chamfer tool to break the edges of the keyring hole.  To create the chamfer simply define the size and select the edges you wan to chamfer, in this case the edges of the keyring hole.

Adding chamfers
Adding chamfers

With chamfers added, the bottle opener is now complete.

Completed bottle opener.
Completed bottle opener.

Conclusions

Onshape is a great CAD program and the fact that you can use it anywhere, either mobile, or on any computer with a web browser is great.  I spent a few months using it as my go to CAD program and I loved the fact that I could design parts on the go with the mobile app.  I think it is a more straight forward program to use than either PTC Creo Elements/Direct or OpenSCAD and the ability to create assemblies is indispensable to a hobbyist.  And with Onshape being web-based and opening up a plug-in community you will always have access to the latest and greatest the software has to offer.

However, I am not a huge fan of some of the limitations the free version of Onshape imposes.  The free version of Onshape doesn’t limit any features available to the user, but it limits how much storage you can use.  A user is allowed to have up to 10 private part/assembly files and up to 100MB of storage, once you hit this limit you have to disable parts in your library that you wont be able to access while disabled.  You can work around these limitations by having your parts be public, but then anyone can see or access them (they can’t make changes to your model, but they can create a copy of it that they can work on).

All in all, Onshape is a great choice for hobbyists, especially those who want access to CAD anywhere.  But, the hobbyist does need to be aware of the space/storage restrictions that are associated with Onshape.

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