bearing yoyo (yo-yo)

UPDATE 2025:  I have designed an unresponsive version of this yoyo using standard size “C” bearings and silicone response pads.  I will post this on the various model sites as soon as I have time.  If you see this in the future and I haven't, feel free to message me and remind me.

A weighted “professional” responsive yoyo with a bearing for doing somewhat advanced tricks and things.

Please read the instructions below. It seems like a lot of steps but if you follow them closely you'll end up with a well balanced high quality yoyo.

You must print this with the outer edge down, like a dome, NOT like a cup. If you print it with the string capturing ridges against the bed they will be too smooth and the yoyo will go down and never return.

NOTE: The hardware specified in this design is inch and fractional because it is common where I live. I do plan to create a metric standard version of this design however I'm not sure what common metric bearings and nuts for weighting are available to people in those areas. I didn't want to accidentally spec some weird size that no one can get. If you know, or can look up what's available at your local sellers that is close to the sizes I have specified here, please leave a comment letting me know. I was thinking M5 would work well for the through bolt but I'm not sure about the weighting nuts.

I have included a STEP file of the design in addition to the STL. I believe in making it easy for people to modify things I make to suit their own needs/preferences. If you have any questions about how/why something was done feel free to ask. (The STEP file does use metric hardware but it's just a placeholder, FreeCAD doesn't have many inch size hardware profiles and since the hardware isn't printed I just used it to visualize the design)

I designed this yoyo with FreeCAD LinkDaily (a fork by realthunder). I provided a STEP instead of the freecad file to avoid people trying to open it in regular freecad. The Assembly uses assembly3 and some experimental external geometry features which only work in the fork. If you'd like the FCStd file please let me know, I'm happy to provide it.

Definition of terms and abbreviations used in instructions:

• OD = Outer Diameter
• ID = Inner Diameter
• Concentric = parts which have a common center so they are equal in roundness

Print Settings

Printer:

Railcore II

Rafts:

No

Supports:

Yes

Resolution:

0.14 Layer height

Infill:

15 (gyroid)

Filament: Hatchbox PLA

Black

Notes:

You must print this with the outer edge down, like a dome, NOT like a cup. If you print it with the string capturing ridges against the bed they will be too smooth and the yoyo will go down and never return.

I'd suggest doing whatever random seam placement you can in your slicer. It will work with an aligned seam but it tends to make things misaligned when they are tightened together.

Parts you will need

Parts:

• 1x 3/16" shaft diameter 3/8" OD ball/roller bearing. 1/8" thickness.
  • you can buy these on mcmaster or ebay for example. It's a common size used in lots of hobby stuff like RC cars.
• 1x 3/16" screw or bolt
  • It should be a pretty close fit on the bearing, if you are using standard hardware store grade you may have to experiment a bit. concentricity is important because the plastic isn't very precise or balanced, so everything else needs to be.
• 1x 3/16" nut
• 12x nuts which accept a 3/8" socket. The thread ID does not matter, they will be pressed into the hexagonal holes in the body.
• 1x bolt which matches the thread ID of the nuts above. This is to assist with pushing the nuts into the hexagonal holes
• 1x yoyo string. This string is pretty unique and has a loop at the end that will be attached to the yoyo. You can make it by twisting a single stranded string with a .030" diameter to make a helical wrap. Or you can just buy it online somewhere.

Preparing the halves after printing

Steps:

1. Remove all the supports and clean all the edges as best you can. The supports on the center will probably need extra care to remove.
2. Sand down anything that's sharp or sticks out from the surface of the parts. There shouldn't be much but the yoyo is heavy enough and travels quickly enough that if there are burrs on the edges they can cut you.
3. CAREFULLY ream out the center hole with a 3/16" drill bit. This hole needs to be very straight and a tight fit. If it isn't it will cause the bearing to seat incorrectly and not spin
4. Clean the string capturing ridges on the inside face with a soft wire brush if you have one. If not move on to the next step, it will probably be fine.
5. LIGHTLY sand down the string capturing ridges while holding each half as flat as possible with the highest grit paper you have (I used 800 grit). You don't need a lot of sanding here, it's just to remove burrs with catch on the fibers of the string.
   • I find it helps to put one finger in the center of the half with the sandpaper on a table, then drag very gently one or two times in a couple directions. That's it, no more sanding is necessary or you'll remove so much of the plastic that the string won't catch.
   • If you don't have sandpaper find some smooth concrete (like a garage floor) and rub it on there a little.

Assembly

Steps:

1. Put the string loop on the bearing. This will be the hardest part of the entire assembly. Have patience. It helps to use the tip of a mechanical pencil to spread the strands apart and make the loop bigger.
   • It seems most people do 2 wraps. I tested both and it works fine either way. You get slightly more responsive return pulls with two.
   • I've included a picture that shows how it should work with the loop.
2. Press the 3/8" nuts into the body halves.
   • Use the matching bolt to help align them by threading it in a few threads, not through to the other side though.
   • Once things are alligned in the hole put the head of the bolt against a solid surface like a table and push them all the way in.
   • They should be extrememly tight so they don't come out unexpectedly. If they are loose and you cant find anything with a close fit you can glue them in with superglue too. Yoyo's spin very fast and change direction quickly, you want to make sure things are secure.
3. Put the 3/16" bolt in one of the halves. It should be very very tight, probably requiring rotation like you're screwing it in. If it's loose something went wrong.
4. Place the bearing with the string attached on the bolt now sticking out of the first half. Careful not to let the string slip off.
5. Check clearance between the string capturing ridges and the OD of the bearing. There should be a small tolerance between them and it should be able to rotate.
6. Push the second half onto the bolt. You'll probably need to rotate it like you're screwing it on again here, so put a tool on the other side to hold the bolt.
7. Before you tighten anything check to make sure your string can fully rotate and isn't squished between the bearing and one of the halves.
8. Tighten the bolt/nut. It should be tight enough that the halves are hard to rotate but not so tight that the plastic bearing seats get deformed. To loose is probably better since you'll have to reprint if you damage the bearing seat.
   • Add some locktight to the threads of the nut/bolt if you want to be sure nothing comes apart.
9. That's it. You should have a functional bearing yoyo. I found that new bearings and new string needs a bit of break in before it will idle for a long time. If the bearing part is working correctly it should be basically impossible to wrap the string up by just winding it around like you would a normal toy yoyo. If you're not sure how to proceed, go watch a beginner yoyo video! With a little practice they are hours and hours of fun.

Category: Mechanical Toys