I’ve been thinking lately about why are bimetal designs really necessary to achieve optimal rim weight? I mean, couldn’t you’d just design monometal yoyo with more of whatever material on the rims? Mass is mass, right?
The only argument I can see is that denser materials can be more concentrated into a smaller area, so the shape of the yoyo might have to be altered more, with a less dense material; which often means bulking up the rims toward the center, and I guess that doesn’t add as much inertia as having more mass toward the out side? What about pushing the material the other way, out from the center? Then you’d actually be accentuating that effect?!
Still makes me wonder, if some of this stuff isn’t just in our heads? Also, “optimal rim weight” doesn’t necessarily mean “as much weight on the rim as possible”.
I wonder if hybrids are better at weight distrubtion than bimetals. Because plastic is lighter and if you have brass than it will have a huge weight difference.
Ding ding ding! This is the reason why. Well, part of it anyways.
You can’t just machine (for example), a 6061’s wall extremely thin and push all the weight to the rims, there’s a minimum thickness the sidewalls need to be to be structurally stable. Coupled with a certain amount of material needed for the hub/bearing seat, and you’re not left with much mass left you can push on the rims with making the thing feel like a rock.
It’s the exact same principle behind plastic YYJ’s with metal rims; higher density material at the rims leads to longer spin times and stability without needing to introduce a lot of weight.
If you look at the edge beyond you will understand what top tier players are looking for.
Titanium and magnesium are the only two possible metals that can perform the benefits of a bi-metal…thus far.
Some draw backs too, like vibe and much less sensitive to string nuances.
Check out Takeshi Matsuura’s spin times for his 2018 worlds performance. He’s using a Turning Point titanium mustang. Prior to this he would use a bimetal for his most of his performances although he played the oversized chameleon light once at JYYC. But his models like the Anubis and palpitation and the colony all are bi-metal. He does use his signature model the Shake and St. Elmo which were designed by Kentaro Kimura to play with the performance and similar feel to the bimetal models. Takeshi and Evan both also use NSK bearings. Hmm #1 and #2 players in the world using the same bearings.
If aluminum is manipulated in the necessary way to achieve the same performance the yo-yo would be difficult to hold.
I guess it does show the trade off of what I was talking about with pushing the building out from the center, having the extra material dictate the shape, but basically exactly what I was wondering about.
Yeah, if that protrusion was stainless steel rather than aluminum, it wouldn’t need to be so bulbous. The need for so much material–when resorting to aluminum on the outer rim like that–has perhaps too much impact on aesthetics.
I prefer to put my food inside the bowl of a normal yoyo, instead of the yoyo being made of food.
That said, I don’t think bimetal is a gimmick. It’s required if you want to target certain rim weights while also having a lower total weight. It is not required to make a good or well performing yoyo. They also look very, very cool, and give the designer additional aesthetic choices.
Using two materials definitely can give a yoyo a huge advantage when the thought and effort is put in. Death Robot MG fully takes advantage of both materials, same with the Draupnir, and many YYF bi metals. Unfortunately, there are also a lot of companies that sell bimetals as a gimmick. Designs that simply throw on an extra metal ring in an attempt to say doing so increases performance. You also have to sacrifice durability for a bimetal yoyo. A piece with multiple materials press fit in together is never going to be more durable than just one piece alone.
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Grendel
(The Voice of All Grendel’s world wide.)
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I’ve never been a cool kid so I don’t own any bimetals. That being said I do have a hybrid plastic/titanium Duncan profly with double pad recess and a hand grooved bearing. Also it was handmade by Skon himself. A plastic yoyo with titanium rims has unbelievable spin time and that’s with my noobish hands. So I’m going to say that bimetal is not a gimmick. Probably here to stay I bet.
I think that some bi-metals that don’t properly take advantage of the density difference of two metals are a gimmick. That said, I don’t have a single bi-metal in which I would make that accusation. Im sure that some exist, but none that I own. Some rings make the yoyo spin longer, some offer more stability, and some both. You could design a monometal with a similar weight distribution, but you would have to add bulk (which would ultimately effect weight distribution). It is impossible to achieve quite the same design with a monometal (you can get close though).
It would be lighter, which is why Jeffry was talking about tungsten. The metals usable for mono metal are very slim - maybe about 3 groups and 15 subgroups od alloys.
I’m going to actually try this -
I’ll get a quote for material on a run of 5 -
If the material price is possible I’ll do a mock-up.
Only potential problem I see if that I will need bar stock with a diameter comparable to a yo-yo. Some material only comes in sheet and plate - if it’s in a plate I’ll need a thickness of at least 44m -
I’ll report back soon.
If I don’t sell them I cut it up and sell wedding bands to fund my next project.
