After spending the summer away from MIT, and having my interest in yo-yoing brought back by the World Yo-Yo Contest (and the fact that two of my classes this semester have yo-yo related projects!), I figured it was finally time for me to make a legitimate yoyo.

I'd dabbled in making 3d printed, and very simple manually machined shapes, and although these worked, they didn't perform anywhere near as well as the machined aluminum ones.

Still not having access to a CNC lathe, I figured I'd make my yo-yos on the MITERS CNC (24/7 access to a CNC mill is very enticing :p  ).

I started off with some 2.25" 6061 round (dubbed the "Yoluminum" by my roommate in freshman year! I can't believe this round didn't get used for some other silly project) and cut off ~1.5" sections, and cleaned up the faces on the manual lathe.

I then milled a flat in order to let the vice have something to hold on to. The vice on the CNC is very small so there's no way I could fit a V block with my stock in it.

Then with the power of HSMworks, a yoyo started to appear!

For the 3d milling features, I went with a 0.005" stepdown (I wasn't satisfied with the result and so I bumped it down to 0.002" for the next few yoyos).

The bearing seat was by far the most painful part. I had to do most of the machining with a 1/16" endmill so feeds were very slow with the limited spindle speed of the machine.

Finished first op.

For the next operation, I machined some soft jaws (there's about a 0.150" tall round feature on the yoyo) and used the bearing seat to keep the yoyo flat.

And with that, I had my first yoyo that I took from design all the way to finished item. You may see a suspiciously similar shaped yoyo hitting stores next year :)

Because it was my first time CNCing the yoyo, my dimensions weren't quite perfect, and the silicone pads were not flush with the bearing seat. Because of this, the yo-yo worked fine for the most part, but was a bit too grippy. To rectify this, I made a new one! And made a silly little display case for the first one.

Improvements for next time:Obviously a CNC lathe is much better suited for this project, but if I still don't have access to one next time, there are definitely some improvements that can be made for the mill.

First, if you look very carefully, you can see that the circular features on the yoyo are actually just estimated tangential lines. This slows down the milling process and leaves a somewhat undesirable appearance. I'll have to play around in HSMWorks to ensure I can get circular arc g code.

Second, I could definitely be more efficient with the amount of material wasted. I really didn't need 1/2" of stock to hold in the vice for the operation so I'll definitely dial it back quite a bit next time.