Cobra 4130 Brushless Outrunner Sketchup Model

So I have been distracted for the last several weeks learning how to use Sketchup. My first exposure to CAD was more years ago than I care to admit during my college days using a Computervision system. Back in those days, a 2D CAD systems ran on stand alone “mini” computers that would barely fit into a typical walk in closet. Since then have worked with a number of 2D and 3D CAD systems through 80’s and 90’s, but it has been over 20 years since I have touched any sort of CAD package. Needless to say, things have come a long way in the last 20 years, and it is quite amazing what you can do with a free CAD program like Sketchup today.

My initial goal was to use Sketchup to design a new custom cowl for my Hog Bipe project. I decided to start with an outline of the Cobra 4130 motor that I will be using on this model so that I could be sure that my new cowl would have sufficient clearance around the motor.

This was my first time using Sketchup, so there was a bit of a learning curve, but I found myself have more fun than I expected. I ended up getting carried away and doing a full model of the motor including the stator, magnets, bearings, etc. I did not go so far as to disassemble the motor, so many of the interior dimensions are just best guesses. Overall, I am extremely happy with the end result.

Cobra 4130 [2] Cobra 4130

It is quite amazing what you can do with this free package! There are some simple tasks that drive me nuts compared to the ‘industrial’ CAD packages I have used in the past, but in general it seems like there is no real limit what you can accomplish. My only real complaint is that as Sketchup was originally intended for architectural applications, it does struggle a bit with certain operations on smaller dimensions (e.g.; < 5 mm or so). The simple workaround is to scale everything up 10:1 for those operations.

If you have any use for this component model in your own applications you can download it here (I will also upload it to the Sketchup 3D Warehouse):


There was a bit of time investment here, but I found creating this model to be extremely satisfying! I am also sure that this investment will pay off in the future as there are plenty for 3D CAD applications in designing and/or customizing RC models.

Next up will be to start designing the Cowl around this motor.

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