hi all, I have made a wonderful discovery. I found out in my wood shop class that there is a lathe the the exact type attachment I need. I think it’s called a 3-jaw chuck (correct me if i’m wrong), and i would love to start modding yoyos. right now I’m working on reshaping my Cerberus to a smaller size cause I’ve been wanting an undersized yoyo. and i would love to mod other yoyos, but could someone tell me a good way to attach the yoyo onto the lathe without putting it onto the bearing seat or the axle?
You need a lot fo experience to do complicates mods on anything metal, so I’d advise you mod cheap plastics. There is a good chance you’ll mess them up if you aren’t experienced.
I figured it out how to take the rims off of the cerebrus so they can fit on the jaws of the lathe.
BTW it was supper beat and uber wobbly so i figured I could salvage it.
Find a bolt the same size as the axle. You can throw the bolt head in the lathe’s chuck.
If you have nothing to lose, then go for it!
If you do it this way, be sure to use a “jam nut” to tighten the bolt to the yoyo rather than tighten it into the threaded insert. Otherwise it may spin off as you work on it.
I hate it when that happens. 
PREFACE: Before you wade through this long-winded, detailed and potentially obnoxious reply, I’ll give you the short answer. It can be done with the setup you’ve got, but there’s a pretty good chance you’ll end up adding tons of vibe to the yoyo with a mod as invasive as chopping the metal rims. If you really don’t care one way or the other, try the method that’s been given already and cross your fingers. If you don’t mind learning a bit and wading through complete sentences, read on.
As a machinist, I can tell you there are quite a few ways to attach a yoyo to a lathe such that you can mess with the rims. I can also tell you that mods on yoyos (especially the more complicated ones) are done on a metal lathe with a cross-slide and toolpost as opposed to the woodturning lathe I’m assuming your wood shop has, and that your setup is probably not terribly precise as far as centering goes (it doesn’t need to be for woodworking, but it does for modding yoyos). That said, there are probably a couple ways you can do what you’re looking to do.
Method 1, as has been mentioned, is to simply put a bolt of the right size into the axle hole on your Cerberus half and use a nut screwed against the yoyo to lock it. This would work with your three-jaw setup, as the bolt head would be six-sided. The primary problem with this is that a three-jaw chuck can easily be off-center as much as 0.003"-0.005". This doesn’t seem like much, and it’s not an issue if you’re just cutting a silicone groove or something, but if you’re cutting a ring of material off the rims that eccentricity doubles. You’re taking an extra .005" off one side and leaving that much on the other side, resulting in a yoyo that vibes more than a dance club. Of course, if you can measure the eccentricity of your chuck and it’s pretty much dead on center, this method might work well enough for what you’re doing.
Method 2 allows you to work around the potential eccentricity of the 3-jaw chuck, but requires a drill attachment for the tailstock. Turn a hard piece of wood down to about 1.5" diameter with an inch or two sticking out of the chuck. Cut a conical depression in the end, like a big giant countersink. Using the tailstock, drill a hole into the bottom of that cone and through the back of the wood piece just a touch smaller than the bolt you’re using. Screw your bolt in through the back long enough to reach into the center of the conical dish, leaving the assembly in the chuck if at all possible (if not, be SURE it goes back into the chuck in the same orientation!). Then, screw the yoyo on the end of the bolt that’s sticking out into the dish and tighten the bolt with a wrench to suck the yoyo firmly into that cone. Begin modding.
(Basically, by doing the whole thing without removing the wood from the 3-jaw chuck, you’ve created a self-aligning arbor to hold the yoyo that is turned concentric with the centerline of the lathe itself, regardless of where the chuck sits relative to that centerline. In theory, it should be more accurate than Method 1, but I’ve never had the need to try it myself.)
Method 3 involves a similar idea to Method 2, but using a 4-jaw independent chuck and some kind of indicator that reads down to thousandths of an inch. Obviously, you will need those two things; if your shop doesn’t have them, skip the remainder of this method. I post it here for reference, and because as a machinist, this is what I’d be most likely to do for a one-time project. In this case, you are allowed to take the workpiece out of the chuck to put the bolt in from the back. When you put it back in with the yoyo attached, use the indicator on the yoyo’s rim to dial it in to center by adjusting the four chuck jaws. There are plenty of tutorials on the internet for dialing in a workpiece, so I won’t detail the process here, but you can easily get within 0.001" of centered, which is good enough for most yoyo modding.
Like I mentioned at the beginning, there are many other ways to do what you’re trying to do, so the biggest advice I can give is to be creative with the resources you have and THINK about how your procedure will affect the concentricity of your work. With all that said, I’m not trying to discourage you from modding at all, and don’t let my verbosity fool you; it’s really not as hard as it sounds if you have or can make the right equipment. I just want to make sure you understand what’s involved in getting a reliably good result from what you’re trying to do. Again, if you’re willing to take a risk, then get creative; there are probably dozens of ways to hold a yoyo on a lathe/drill-press/Dremel/router (BAD IDEA!), and some will be more concentric and reliable than others. Good luck and happy modding!
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Just wanted to note that it’s absolutely possible to do high end, high precision mods on a wood lathe… Takeshi, Eric Wolff, Taka, and many others work on wood lathes.
I do NOT however, suggest cutting into metal in any form on them… the tools aren’t designed for it. You’re fine with wood/plastic.
Kyle