I design and modify a lot of parts for 3d printing. Many of those parts have to fit existing things. In my case, they have to fit game controllers because I run a charity called TheControllerProject which supplies parts to help folks who have physical disabilities be able to play video games. I also do similar work for a gaming charity called AbleGamers.
Designing parts for 3D printing that actually fit an existing item can be really frustrating. There are many ways to pull this off. I use several methods, but I’d like to share one of the more daunting seeming processes in order to de-mystify it. Let’s 3D scan something and make a 3D printed file to fit it perfectly.
The idea
The folks at AbleGamers need a cheap joystick that can stand up to some abuse. In the world of gaming with disabilities, there’s a common need for a joystick with a top on it we call a “goalpost”. This is typically for people who have a lack of muscle control or quadriplegia. Pretty much anyone who is lacking in fine motor movement, but still has broad muscle control of the shoulder can use this. It is pretty common to be able to move an arm, but not control the wrist.
Folks rest their hand on top of the goalpoast and use the broad muscle move things around. This means the goalpost has to support a lot of weight. There are tons of joysticks out there, but the nature of this issue means that more options are always better.
We start off with this logitech flight stick. It only costs $30 and works with the Microsoft Accessible Controller. That’s considerably cheaper than most of the existing options out there, so this is a good candidate.
My initial goal was to create a goalpost that could be 3d printed and attached to the joystick itself without any disassembly or modification. This option is great because it means that more people can install it without advanced skills or the fear of ruining their device.
The 3d scan
Since the flightstick is a fairly organic and complex shape, I didn’t want to do a million measurements and try make something fit by eye. Sometimes that’s the best approach, but in this case I felt a 3D scan would allow me to more quickly and easily get to a shape that fit perfectly.
First I tried to scan this with the Revopoint Pop2 3d scanner. It has trouble with the black plastic, so I had to coat the joystick in a 3D scanning spray. This resolved the issue with the scanner not seeing the joystick, but I had another big issue that was very frustrating.
For some reason, the scanner’s gyroscope would go haywire mid-scan. This was a huge problem. Every time I tried to go around the joystick to get a complete scan, the device would think I was flipping it all around and the scan data would be trashed. I don’t know if my scanner is broken or what. I do know it was not able to get a complete scan that was usable.
I decided to hop into RealityScan on my iphone and give it a try. This is a free app, at least for the first few scans. I had my doubts about how accurate this scan would be since it is photogrammetry (using multiple photos to reconstruct the 3d model) and the joystick is a material that doesn’t show variation much in photos.
I was quite pleasantly surprised with the quality produced by RealityScan. Above, you can see the model hosted on Sketchfab. Remember that the goal here was to capture the shape of the grip specifically for 3d printing, so I didn’t bother getting the whole thing to look perfect for use in more visually demanding situations.
download and convert in blender
I downloaded the file and it is an .fbx file. I couldn’t get that to open in Fusion 360, which is my typical CAD design software of choice. To get to a place where I could work on this, I needed to convert it to something Fusion would recognize (though I really thought it should use .fbx, so someone let me know if I was just doing it wrong).
To convert this model I chose to use Blender. I simply opened it in blender, made sure the model was selected, then chose to export as an .stl file. If you’re more comfortable in blender than Fusion360, you can of course stay within this package and model things. I prefer Fusion for anything that needs precise measurements, so I only used Blender to convert the model.
load into fusion360 and convert
In fusion 360, I started with a new blank document, and then imported the mesh.
After you have imported the mesh, you’ll need to switch over to to the mesh tab, so you can edit and clean things up a little bit.
After you have the model in a more presentable fashion, you can convert it. This will make things easier later when you use it as a cutting tool.
After you model your desired shape around the 3d scanned object, you’ll use “join” to make the cutout. I know this sounds counter intuitive, but the “join” tool is basically what you would call “boolean” in most 3d modeling packages and allows for adding or subtracting using a shape. In this case, we want to subtract.
After subtracting the joystick from my newly modelled accessory, it will fit perfectly.
You can see the result here in more detail. While this isn’t the prettiest, it is functional and worked quite well.
And here is the result. You can download it here.
Of course, as I stated in the video, this isn’t the best solution. It’s so tall. Not only does this make it difficult to mount ergonomically, it means that the motion necessary to hit the full range is exaggerated, not really optimal for someone with motor issues.
Ideally, I’d design a very short version that incorporates all the buttons and things so there’s no loss of function, but in the short term I’ve designed this goalpost that completely replaces the joystick. You literally just chop off the wires going to the buttons though, so not ideal.
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