Yoyo CAD & Prototyping Adventures

@JoMatt I appreciate the really useful feedback and comments/suggestions. Really interesting comment about the YYF Edge and Evan’s discoveries and thought process in its design. In my opinion I think the Edge has a little too much mid-weight for me and my style/preference. It is a great yo-yo for sure, but when I bought a YoYoFriends Hummingbird I appreciated the outer rim weight more for me (made it more stable IMO), and I liked it more than my YoYoOfficer Hatchet + I had recently purchased (which is arguably similar in ring placement as the Edge which I have also played often). Also the Edge is 46.75 mm wide, where my design is 42 mm wide, would this difference in width make a difference in how it feels/plays?

I am also glad the Draupnir was mentioned, because just like the Hummingbird, there doesn’t appear to be much mid-weight to the yo-yo and I still think the 63g Hummingbird plays nimble?

@MarkD I took your 0.41 mm filleting measurement, and filleted the entire yo-yo. @JoMatt would this 0.41 mm fillet, where the string comes off the yo-yo, be good enough to avoid string cutting issues?

Also the Mass Moment of Inertia is below. Not really sure what it means lol. I’ve got to go back and watch all your videos from Post # 10. https://www.youtube.com/watch?v=gb1UGeYnzwk

Below are the stats

Nice suggestion to fillet the edges, it doesn’t change the look very much at all.:+1:

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You would still have to add some midweight with your design. The reason you found the Hummingbird to be more stable than the Edge & Hatchet+ was not because of the ring placement. Don’t forget that the Edge & Hatchet+ have 6061 bodies making it more difficult for a more precise weight distribution with the higher safe machinable thickness limit. This is why I find the concept of 7068 or 7075 body bimetals to be more reasonable. The only 6061 bimetal I ever liked was the G2 Elite.

The Hummingbird has a 7068 body which means it can have a thinner body while pushing more of the total weight towards the rim. You could see the rim of the Hummingbird not having a totally flat inner rim though. It actually has one of the design choices I mentioned which is the inward-slanting rim design. It doesn’t slant that much though since it already has a centerweight dimple to complement the rimweight. You don’t have to focus too much on midweight, you only have to add a little to avoid a lot of issues. (sluggishness, kickback & more) I recommend checking out the Mowl M & ThrowRevolution Zephyr. Those are rimweight-focused monometal yoyos, but they added a little bit of midweight to get that perfect feel without some the issues I mentioned. The Mowl M even has similar specs to your design coincidentally.

As for the filleting measurement, I find anything lower than 1mm to be uncomfortable. 1mm would be my safe measurement but some designs can still be uncomfortable so I bump my V-shape designs towards the 1.5-2mm range.


It depends on where the fillet is and the angle between the two sections, of course. For @Mark_Leithead’s design I’d recommend rounding off the inner + outer edgesof the rim a lot more - outer probably at least 1mm, inner maybe double that - that’s going to hit you in the meat of your hand a lot.


Here’s the 2.0 version. Changes made include:

  • made the response grooves deeper to accommodate Snow Tires (from .85mm to 1.9mm)
  • made the gap just a little bit narrower (from 4.6mm to 4.4mm)
  • modified the inner cup to accommodate the changes to the response.

I feel like the last version was a little bit too sterile for being an organic yoyo. I think this way will give it more of the Canvas’ personality. One of the things I love about the Canvas and Parlay is that they have a very snappy response.

All of the other dimensions are virtually the same as before. I’m stoooooooked. Again, the vision was a conceptual mash-up between the One Drop Top Deck and Canvas/Parlay- a supercharged classic in 7075 aluminum

Weight: 66.55g
Diameter: 55.4mm
Width: 42.8mm
Gap: 4.4mm
Ixx: 15,890


Such good comments!

I watched the four Yo-Yo Design 101 videos made by ZachTheSloth on Youtube (links in post 10 in this thread, posted by @MarkD) and I calculated the Center of Mass and determined where it fell along the chart Zach provides in one of his videos.

I also added a bit more mid-weight as suggested, by elongating the inner-rim towards the middle of the yo-yo. Filleted 0.9 mm everywhere.

Seems like my design falls more on the spectrum of ‘stable’. I am ok with this as I want it to be a 63g monometal that has some stability and speed.

Now the next step is understanding Mass of Inertia:

           Mass of Inertia for 1/2 of Yo-Yo at xx axis (yo-yo axle): 13,880 g mm^2

           Mass of Inertia for Whole Yo-Yo at xx axis (yo-yo axle):  28,010 g mm^2

Still not sure if I need to calculate the Mass of Inertia for the Sketch, or for the 1/2, or for the whole yo-yo. Also still not sure what the numbers above mean.

Would be cool if there were some stats on Mass of Inertias of some common throws, or if even a scale gradient exists for Mass of Inertia as for Center of Mass/Radius as shown below.

Some progress…

For the image above:

In order to determine where is the Center of Mass for the 1/4 of a yo-yo, you need to Elongate the Sketch to create a Body first in Fusion 360.

After you create the elongated Body, you need to go to ‘Inspect’ and then ‘Center of Mass’. Then Fusion 360 will calculate where exactly the Center of Mass is in order for you to determine the Y-Axis Center of Mass measurement needed below:

Now to try and understand what these moments of inertia mean, and if they are even calculated correctly (ie. whole yo-yo, 1/2 yo-yo, something else?)

A tip for new users: the 2D Sketch is the most important part of the design. If you revolve and mirror your Sketch to create a 3D Body, and then you realize you want to edit the design, then I highly recommend to delete the newly created Bodies and to edit the 2D Sketch, and NOT to edit the 3D bodies. Then after editing the sketch, create new 3D bodies, then delete the bodies, edit the Sketch; repeat. Why do it this way? Because I have not found a way to create a 2D Sketch from a 3D body.


Thanks for the rim weight/moment of inertia tutorial! I like your drawings.

The moment you highlighted is actually around a different axis. Ixx is the one you want, which goes through the axle. 13,880 g mm^2 sounds pretty nice for the half and it matches my intuition for the design & the rim weight quotient you calculated (which also looks correct).

The Diffraction has a moment of 14,360 and a rim weight quotient of 57.9%. The total mass is about 64.35g assembled (depends on pads/bearing used with a 8mm steel axle). It turned out really good (in my opinion) in terms of stability/etc.

Throwcafe published some of the technical specs of the boba on their blog. Here’s what they said:

The technical stuff

Each half has a moment of inertia of 14870 g mm^2 and weighs about 31g, for a total yoyo weight of just under 64g. In comparison, the Cappuccino’s halves weigh about 30g and a moment of 13700 g mm^2.

An organic shape lets you put more weight where you want on the yoyo, and here it’s mostly rim weight. While the Cappuccino’s light weight and decent stability make it a speed demon, the Boba is a bit slower, more stable, and fun as an everyday throw.


Man, this information is so useful.

Very cool, and again very useful.

Dude if this hypothetical yo-yo would play anything close to your Diffraction (which I obviously have not tried), but following your comments, I’d say this design would be a huge success heheh

I also got my Sengoku Coldfire, and it is a very good yo-yo but different from what I had imagined when creating my design (as it was not in my mind when I designed my yo-yo).

Anyways some digital renders of the design, and pics of the yo-yos that inspired the design. The Coldfire is there for a coincidental comparison, and it may influence my design further.

1-%20copy 2%20-%20Copy

Following @MarkD and @JoMatt’s suggestion to inspect yo-yos I like and to try to incorporate their design into mine, I notice that these 3 yo-yos have pretty different interiors, especially right after the response pads. I enjoy the Hipster Highlife most when it hits the string, and I wonder if this little concave recess helps with that? I’m looking for a smooth feeling when the yo-yo hits the string, instead of a distinguished sharp feeling:

I also see Vosun offers custom yo-yo making. I might ask for a quote from them, as I enjoy their Vanquish, but want it not bead blasted. Also might contact FPM (info in Posts # 81 & 90)

I am digging the 42 mm width… the camera ‘curved’ the Coldfire’s sides below:


The hipster highlife also has a relatively high wall floor a modern unresponsive yoyo - this affects the feel a lot. Also check to see if that area is bead blasted or smooth/masked.


What do you fine yoyo people think?

Cup design #1
Cup design #2

  • Cup design #1
  • Cup design #2

0 voters


I wanna fingerspin #2 sooo bad!

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Me too buddy. Meeeee too.

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Nice one, looks like you’re honing in on the design. I chose #2 based on looks alone, I don’t think I can comment on playability differences. You do make me reconsider adding a finger spin hub to my design…

Looks like the Hipster Highlife is all smooth/masked. I also noticed the little concave recess and ‘raised hub’ is also on the OD Kraken I have, provided to me by an anon I had never met cough @codinghorror cough thanks, did you ever think I’d be inspecting the inner walls like this when you sent this to me??

I also see the Chief has this raised hub and concave part. I mention the Chief because I know it inspired the design of the Hipster Highlife (as did the SPYY Punchline that has a minimally-raised hub):


I also made a math error previously. The true Rim Weight Quotient is 60.6% for my yo-yo (16.9 mm (not 15.9) / 27.9 mm), putting it on the side of ‘more stable’ along the distribution of yo-yos. This works out better for me and makes more sense when looking at the design. It also shows you don’t really need to go too extreme in wall thinness to maximize rim weight (my walls are 2 mm thin, 6061 aluminum). My original post was corrected but below is the corrected image too.


Yeah, with monometals the shape of the rim has a big effect on weight distribution. It’s easier to get more rim weight if you have broad, flat-ish rims.


Wait, that’s a spike, not a finger spin hub… both of them have spikes… which can be pull started and finger spun.


I wanna pull start #2 soooo bad!


I voted #2 - That yo-yo looks great @smileypants707, you have estimated specs?



Specs Cobra Lilly v2.1
Material: Al 7075
Weight: 66.2 g
Diameter: 55.4 mm
Width: 42.8 mm
Gap: 4.39 mm
Ixx 15,880
COM 66.3

ooh nice, I call dibs if you ever make a run! :laughing:


Any more voters?



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