Sketches to Models to CAD

I often work backwards, going from Sketches to Models to CAD. However, it works for me as it allows me to create something in the workshop. Sometimes I think this works really well and I think a good example is the five cylinder rotary engine. The only sketch I have of the engine before making it is this one.

five cylinder rotary engine sketch

Hence I’m now opening up the CAD and working to recreate the engine. I’m also having to dismantle the engine to get some of the key dimensions. The piston is just 9mm in diameter.

five cylinder rotary engine

This engine is rather gorgeous on the inside, these parts rarely see the light of day. It might actually be nice to make a perspex cover for the engine. I will have to think about that.

five cylinder rotary engine with CAD

Mixing CAD and real parts is rather fun. FreeCAD is my software of choice. It is completely free and yes it does have a learning curve that you need to face to get the most out of it.

However, persevere and it is rewarding. I find the process of adding constraints within sketches quite interesting. It is very similar to the way you think about fixtures, alignment and machining choices.

five cylinder rotary engine CAD

The engine CAD is taking shape. I use Assembly 4 plugin as this allows me to create each part within FreeCAD and bring them all together.

At the moment I don’t add thread details, but show holes at tapping diameters and bolts as overall OD. I then mark these up later to indicate what needs to be threaded.

So, I’m still early days in terms of learning CAD. I’m enjoying creating CAD, but feel that I still have a leaning to go Sketches to Models to CAD.

Do I need to turn this around or will I lose some of the design inspiration that I get when working in the workshop?

PS: this does mean I will make plans of the tiny engine available via this website in the near future.

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