Alright after a change of 0.4mm to the inner diameter I am up to a weight 31.5 grams for one half. Is this good?
Does it meet your design goals? What’s the mass moment of inertia?
Don’t forget axle weight
My design goal was to make a Yoyo very similar to the Spotlight Ultra yoyo but one with a fingerspin hub, more rim weight, and wider. I think I succeeded? I am not sure how to calculate the moment of inertia but using ZachTheSloth’s tutorials on youtube and using his way I got a number of 60 which is supposed to be stable and harder to regen. If I wanted to manufacture this yoyo how would I do that and how would I get a quote on the cost? I don’t have much money so I’m guessing it will probably be out of my price range but it would be interesting to know.
You’d want to save up about $500 to prototype something like this.
You should work on multiple other designs first though. Usually not a good idea to manufacture the first thing you come up with, especially not something this derivative.
There are some design issues with this also -
- the outer rims appear very sharp (what is the radius there?)
- the fingerspin dimple is very shallow and small (compare its size to your fingertip to see why)
- The cup around the fingerspin dimple leaves a super thick wall section that adds center weight, while also not helping the fingerspin ability at all
- You definitely need to figure out how to calculate the MMOI in your software so you know the full specifications of your design. You should solve this before thinking about manufacturing anything.
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Radius for the outer rims is 0.5mm should I make it a larger radius? I noticed the fingerspin/centerweight problems but I wasn’t too sure how to resolve them so I just left them. The software I am using is onshape.
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Yes. try 1.5mm or higher.
0.5mm will be incredibly uncomfortable to catch
I can’t help with OnShape but check the help/faq/guide systems to see if you can find it. Might be in the “Mass properties” section.
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@MarkD
This is supposedly the MMOI:
Is that a good MMOI? Or I guess is that a stable and long spinning MMOI?
Is the center weight and rim fillet radius better?
Specs are now:
53 mm wide
56.5 mm diameter
Weight of one half is 31.5 grams
An MMOI of almost 16000 for a monometal is good. However, this yoyo will be around the 70g mark.
The AL looks quite thin at the bearing well.
The radius on the rims looks fine now.
The inner wall just past the response pads is almost flat. This could possibly interfere with some tricks? I’m not 100% certain.
Yeah, looks better. I echo Glen’s comments, though this looks like a 66g assembled design to me (31.5 * 2 + 3)
How thick should the aluminum be at the bearing area? I originally wanted to yoyo to be from 64-65 grams so I just need to adjust a few things. I’m not too sure what the inner wall is could someone elaborate? Glen said that an MMOI of almost 1600 is good but is that 1600 or 16000?
Depends on the material. Usually around 1.6mm for 6061, down to 1.0mm for 7068
Glen meant 16,000. 1600 would be insubstantial.
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Alright everything should be 1.6 mm from the bearing seat now.
I think I will leave the weight at 31.5 grams.
Is this the final design or are there a few more things to work out?
Specs:
52 mm width
56.5 mm diameter
31.5 grams half weight
At 31.5gms you’re a bit heavier than your target. The last thing to sort out is the axle length and calculate the weight to add into your total. The other thing to think about before going into production is to think about how you want it to play to move some weight around on the rim.
@Simyo
I think I am okay with going a bit heavier than my target. The yoyo is designed for a 10 mm axle so the weight should be 31.5 * 2 + 2(bearing) + 0.6(axle) ≈ 65.6 grams? I have no idea how to tell how a yoyo would play by looking at the design. Does anyone else know? This is my first yoyo design.
You can tell based off of the numbers you gave you can compare it to other yo-yos. I understand enough of the science to know that I don’t understand it completely. That being said visually it looks like it will play a bit on the heavier side. Hopefully someone will break down the science of the numbers into how it plays.
Alright thanks!
Made a new yo-yo.
Thoughts anyone?
Specs:
Width: 49 mm
Diameter: 57 mm
Half Weight: 32.66 grams
MMOI: 17094
Is the axle hole the proper size for an eight mm axle? I also wish it were a little bit lighter from 31.5 to 32 grams but I don’t want to bring the MMOI down to under 17000 so I’m a bit conflicted.
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My bad, I sometimes accidently add in the weight of Cabal guts bearing seats in the equation.