This is a Print in Place U-Joint designed to fit on standard Vex drive shafts.

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Essentially, I got tired of students breaking the U-joints that you can buy from Vex when working in class on non-competition projects. So I decided to model one of my own. I started out with one that required M3 bolts/nuts, but decided that was too much work.

This model prints in place, and uses about 3 grams of plastic. I've been printing these in PLA. The drive shafts are press fit. They start super tight, but obviously the more they get used, the looser it gets. They print so fast and cheap that once they won't hold a drive shaft on their own, I toss them in my PLA recycle pile and print new ones.

When you print them, you just force them to bend along the axis, and it snaps the printing wall supports. The get looser and easier spinning as they get used and plastic erodes away during use.

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There are 2 versions:

Version 1 is Pre-supported. It includes a small block on the under side of the central shaft. This version prints the best and runs the best out of the box. Just bend the U-Joint to expose the support block, and snip it off with from flush cutters.

Version 2 has no pre-made supports. You CAN print this with no supports at all, it just looks a bit more ugly, and takes longer for it to spin smoothly. You can also add slicer generated supports, I printed them with ‘Build Plate Only' checked. I have printed then with both Tree and Standard supports. Both worked, but the standrd supports seemed to produce a smoother running UJoint.

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Designed in Fusion 360.