Looks like just one shallow V groove. No trenches.
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Ah, that part. I see.
The weird knots that would form . I could dig it
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@MarkD @hobbygod I was talking to a couple of people who designed or worked with designers on two different yoyos and both said that their designs had vibe or wobble. I asked if it was the design or the machining and one of them said definitively “the design.” You throw it, it’s wobbling, you straighten it out, it’s smooth for a bit, then it starts wobbling again.
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There are particular sizes/distributions that seem to accumulate pulse vibe, but you can usually fix it by making the yoyo wider OR taller OR narrower OR smaller, just to get away from the danger area.
I don’t actually know how to determine where the problem zones might be! I’ve had a couple of my own designs suffer from this; they died in the prototyping stage.
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Is there some physics or engineering principle that could predict this so it could be avoided in the design stage? Seems like Newton’s laws shouldn’t allow this.
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Even a well machined yoyo is neither perfectly concentric nor perfectly rigid, so there’s a lot more complexity to consider. I haven’t really dug into it too much, I’ve only seen the experimental results.
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What experiments are there on this?
I assume @MarkD is referring to the prototypes that failed as experimental results.
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Is there any modeling software that could be used to simulate the behavior of yoyo prototypes? I would expect that to be significantly cheaper than making prototypes IRL.
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I have access to solidworks and simulations through school for a couple months. I’ll give it a shot! I only have yoyo models made for 3d printing so well see what the results look like.
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I know Onedrop has somebody do this for them but I don’t know how, as the person who does it has an PHD in physics and just gives the numbers to Onedrop.
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I know there’s the intermediate axis theorem that says rotation of an object around a particular axis can be unstable, although this shouldn’t apply to yoyos because there’s no “intermediate” moment of inertia - two of the three principle axes of rotation are equivalent. So just take this as a fun fact and nothing to do with yoyo design lol. If I have the time I’ll try to work out some math to see if I can figure out what’s happening.
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id probaby try onshape lateron, it does look like a good program to do renders fast
The free version of Onshape does not include rendering which is why I use Fusion 360.
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i see, then ill still stick to freecad then 
Well, I still use Onshape to design though.
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Yoyo:
Specs:
Width: 48mm
Diameter: 56mm
Half Weight: 29.586gms
Assembled Weight: 62.07gms
MMOI: 14086
Axle: M4 x 8mm x 0.7mm
Bearing: Size C
Body Material: 7075 Aluminum
Yoyo + Screw on Fingerspin Caps:
Specs:
One Cap Weight: 1.7gms
Cap Material: 7075 Aluminum
Caps + Yoyo Weight: 65.47gms
Yoyo + Screw on Flat Caps:
Specs:
One Cap Weight: 1.39gms
Cap Material: 7075 Aluminum
Caps + Yoyo Weight: 64.86gms
Only problem with this is I need to figure out a way to unscrew the caps or they will be stuck screwed in forever. Any suggestions for types of caps/different material caps? Or any suggestions for different yoyo/cap color schemes? I couldn’t think of any good ones. I would welcome thoughts/criticism.
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If the caps had a hex-key interface in the base it would be possible to drive them out after taking the yo-yo apart and removing the axle.
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Hmm. That is a good idea! I will put that in. Any suggestions for different caps?
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