You need more than just the taps to tap something. The first thing you do is drill the object, in this case a yoyo, to the correctly sized hole. For a M5x0.8mm tap, you need to use a 4.2mm, or #19 drill bit. To drill the hole straight and centered, a lathe is generally preferred for the job, or a drill press at the very least. Tapping should also be done on the lathe as well, to make sure the tap goes in perfectly straight. I like to start tapping on the lathe, and finish by hand. Also, if you want to use the same axle, you would need to install helicoils, which are threaded inserts, but generally it’s not necessary, there are some special cases, for example, if the yoyo uses spacers and can’t afford to be tapped to a larger diameter axle. If you don’t have a lathe or a drill press, you may get away with just tapping to the next size up, 8-32. This is safer to do by hand as the old threading will act as a guide and no drilling is necessary. Keep in mind though, that this won’t last as long as if you were to tap to a M5x0.8 sized threading. If you want to go ahead with the 8-32 tap, look for the bottoming one, as that will make the most of the room available. If you have any more questions, just shoot me a message!