Yoyo CAD & Prototyping Adventures

[MarkD (Mk1 Yoyos)]

About a month ago I realized that designing your own yo-yo and actually prototyping it is a lot more approachable than I thought. There’s a lot of great CAD software out there, a lot of it free to use for this purpose, and there are machine shops that specialize in yo-yos, even for one-off runs. The price for this is expensive, but I’ll end up with something real, and personal, and special.

I started learning CAD using Fusion 360, which has a free startup license that you can activate from the free trial version. It has several features that are really useful for this sort of work - it can analyze mass and moment of inertia, apply different materials (6061, 7075, stainless steel, etc), and it even has a pretty nice rendering tool.

I made a bunch of practice designs, but most of them weren’t very appealing to me.

For practice, I also tried to mimic some existing designs. Can you guess which ones?

I also tried a couple bi-metals, but those seem a lot harder to design. There’s a lot of work to balance the weight of the steel & aluminum parts while also providing enough surface area for the press fit.

I finally ended up with something I’m pretty happy with:

This is very likely something I’m going to get prototyped in a very small run, by the folks at FPM (YoyoFriends). Maybe it’ll be good? Who knows!

Are any of you practicing your CAD? Done any prototype runs for fun? I’d love to hear your stories & see your designs!

[CosmicCaleb]

Here is my first yoyo design. The Wildcat. This is my first time ever doing a design, so feel free to tell me that it would be totally unplayable or unmachinable, but please give me some constructive criticism.

Specs -

Weight: 63.2g
Width: 48mm
Diameter: 54mm
Material: 6061, Stainless Steel
Gap: 4.38
Bearing: Size C
Response: 19mm

[yomega_fan_335 (The Yo mast3r)]

The edge of aluminium behind the ring is way too thin and fragile. I would suggest making it at least 1.5mm thick if using 6061. Can be thinner if using 7075.

Still, good designs mante.

[codinghorror]

How much thinner can it be for 7075? Also how do you test for proper yo-yo strength? Toss the inevitable manufacturing rejects on the ground and see what happens?

[yomega_fan_335 (The Yo mast3r)]

Or you can run a CAD simulation if you have the right knowledge.

[CosmicCaleb]

I noticed that as soon as I posted this. Also, how thin would you recommend the walls? My thinnest wall is 1.07 mm.

[yomega_fan_335 (The Yo mast3r)]

If 6061, at least 1.5mm, 1.2mm for 7075

[CosmicCaleb]

Well then, whoops. How thick for 7068? And what is the density of 7068 compared to 7075, because they don’t have it on Fusion 360?

[CosmicCaleb]

Slightly Revamped Wildcat

Do I have too much centerweight? I feel like I do.

Weight: 62.9g
Width: 48mm
Diameter: 54m
Material: 7075, Stainless Steel
Gap: 4.38
Bearing: Size C
Response: 19mm

[CosmicCaleb]

Wildcat Monometal

Specs -

Weight: 63.9g
Width: 48mm
Diameter: 54m
Material: 7075
Gap: 4.38
Bearing: Size C
Response: 19mm

[MarkD (Mk1 Yoyos)]

Good progress! I think mono-metals are a lot easier to design, especially for a first one, which is why I’m focusing my time on that. I see you also rounded off the edge of the response, which is a good catch.

The outer edge of the rim looks sorta sharp - what’s the arc radius there?

For anyone else reading, here are some good resources to get started, a youtube tutorial series by Zach Lerner:

• Lesson 1: The Guts
  • Lesson 1a: Mass Moment of Inertia
• Lesson 2: Design for Performance
• Lesson 3: Limit State Design (Machinability)

Here are some general rules for wall thickness that I got from Jordan, the owner of Smashing Yoyo Company:

• 6al-4v grade titanium is 0.5mm
• 7075 is 1.0mm
• 7068 is like, 0.8 mm
• 6061 is 1.5 mm

He tends to add 25% unless he’s going for something extreme - too thin and it can warp during machining. Also, don’t create a thick part surrounded by two thin parts.

[CosmicCaleb]

Zach is the same guy that I watched to learn how to design the guts. And, yeah, I might want to change the outer rim. There is an arc, but I think I made it super small, so I am going to change that.

[yomega_fan_335 (The Yo mast3r)]

Better. But I would suggest you to taper the ring so it doesn’t slide off either side.

[CosmicCaleb]

What do you mean by taper? I see what you mean that the ring could slide off, but what should I do?

[yomega_fan_335 (The Yo mast3r)]

Draw the bottom of the ring slanting upwards or downwards.

[CosmicCaleb]

This is a different yo-yo, but something like this? (Except the ring would be on the edge of the yo-yo).

[MarkD (Mk1 Yoyos)]

I’m pretty sure anything where you can press it in on one side until it fits against something would work. I haven’t seen many cutaways of bimetal yoyos, though.

[CosmicCaleb]

How about that?

[MarkD (Mk1 Yoyos)]

Someone with experience machining steel rings will have to chime in, but that looks like it’d be a pain to machine since the ring would have be done in two steps instead of one. I think they normally have one or two sides completely flat in most cases.

[CosmicCaleb]

I’m just going to stop trying with the Bimetal Yoyo.