Do titaniums outdo(?)bimetals?


#1

Was curious,

heard titanium could put a lot of weight on the rims due to it being so strong, but is it equal to that of a bimetal?


#2

Full stainless steel prototypes
‘Immortelle’
52/64
http://i.imgur.com/fn1mDiR.jpg
http://i.imgur.com/4waaFMM.jpg
http://i.imgur.com/vl9ASgv.jpg

‘Precentor’
56/66
http://i.imgur.com/EawpVP6.jpg
http://i.imgur.com/WlQkn4w.jpg
http://i.imgur.com/BczjOj4.jpg


#3

Actually steel is stronger in similar volume but ti is about 40% lighter. What ti really has going for it is tensile and fatigue strength. It can be formed thin and have excellent durability unlike aluminum. A lot of design possibilities.

Anyways something like that.


#4

Ti is 40% heavier than Al as well
edit: just checkd
specific strength of Ti and 7075 Al are very close and both are among the highest in metals


#5

The performance is in the execution of the design, pretty much independent of the material.
=> Expensive material, shoddy design = poor or mediocre yoyo
=> readily available, low cost material, careful design = good or great yoyo.


#6

If anything cheaper materials yield better design through many variation. Just how many ti yoyo’s are there compares to pure aluminum? The threshold for the best throw may lay in ti but who’s going to expoit the 1000’s of designs to discover that yield?


#7

Exactly this. Material difference doesn’t equal performance difference.

There’s a huge myth out there that “bimetals outperform single aluminum yoyos”. I just don’t get it. People see “bimetal” and automatically assume that yoyo must inherently outperform all metals made with a single aluminum.

Same thing seems at play here with this question. Titanium is an expensive metal that offers different design possibilities. That doesn’t mean performance will be higher in a yoyo just because it’s made with Titanium.


(Amplified) #8

hmm. I think I agree with Greg on this one.


#9

Sorry, seems like my wording isn’t quite right :stuck_out_tongue:

In a situation of a draupnir vs, lets say, a czm8, what word would be used to describe the difference?


#10

price


#11

https://i.imgflip.com/jveir.jpg[url=https://imgflip.com/memegenerator]


#12

ok i thought u meant t new vk


#13

Country?


#14

Agreed. I wasn’t impressed by the Ricochet at all, which is why I’ve been so happy to take a blowtorch to it. Likewise the God-Tricks Trump was an aluminium/steel bimetal and that can barely keep up with my Shutter. Design > Material.

As for Draupnir compared to a CZM8 I would say the difference is in the feel. When you pay for a Draupnir you’re paying for the performance at such a light weight, which is where bi-metal design shines. If you made a 62g aluminium yoyo you wouldn’t be able to get the same performance as you get with the brass-ringed Schneider Mark 2.

Look at NathanC, we all know he loves very light yoyos, so bi-metals mean he can still get the performance he craves without venturing into heavier territory. That being said, besides “feel”, there isn’t anything a Draupnir can do that a CZM8 can’t. Apart from make your wallet lighter. :stuck_out_tongue:


#15

I thought u were being witty :stuck_out_tongue:

Was just wondering what the right term is for a difference in overall-general-playability of a yoyo, so I was using what many consider to be the king of v-shapes, the draupnir, and a budget metal from yff, the czm8


#16

As said the specific strength of 7075Al and 6Al4VTi are extremely close so as long as you are using a material heavier than both on the rims there shouldnt be a large difference
The current trend of Al design is clearly shifting towards wide rims instead of thick rims to counter the shrinkage of effective rim radius when their volume is reaching the limit.


#17

I know design is a large factor, but when we’re dealing with a company as experienced as Yyf or OD, we don’t really have to worry about a bad design. So let’s compare the OD bi-metal and the OD Ti… wait… Paul is the only one on these forums who really has played both. Please answer with the pros and cons of each PAULLLL WE NEED YOUU.


#18

There’s a lot of variation in the specific strength (aka, the strength-to-weight ratio) of metal alloys, depending on various factors, such as the heat treatment that the alloy underwent. The ranges of specific strength for aluminum and titanium are as follows:

6061 Aluminum: 48-144 kN-m/kg
7075 Aluminum: 86-211 kN-m/kg
Grade 5 Titanium (Ti-6Al-4V): 226-264 kN-m/kg

I’m not sure where the specific strength of the aluminum/titanium used to make yoyos is within each range, but as you can see, titanium has a significantly higher specific strength than aluminum, unless the manufacturers are using 7075 aluminum that has a specific strength at the upper end of its range. This is why titanium is superior to aluminum.

The higher specific strength of titanium allows you to use less material (mass-wise) in the walls of the yoyo while maintaining structural integrity. This allows more weight to be allocated to the rims of the yoyo, while maintaining the yoyo at the desired overall weight (e.g., 65g).

Rim weight is especially important for yoyos, as it directly affects spin time. If you’ve ever taken a basic physics course, you may remember learning about the moment of inertia. Essentially, the moment of inertia is a measurement of how difficult it is to get an object to stop rotating about an axis, due to the momentum of its rotation. The moment of inertia for a point mass rotating about an axis is equal to mr^2, where m is the mass and r is the radius of the trajectory (i.e., the distance from the point mass to the axis). As you can see, the moment of inertia increases significantly (by a square factor) with increasing radius. This is why rim weight is so important. If you had 10g of material allocated 20mm from the center of the yoyo, that 10g of material would exert a moment of inertia of 10g x 20mm^2 = 4000 g-mm^2. However, if that same 10g of material was instead allocated 25mm from the center of the yoyo, it would exert a moment of inertia of 6250 g-mm^2, 56% more than before! The result would be significantly higher spin times.

I hope this clears up some confusion for people. ‘Rim weight’ is a term often thrown around, but I hadn’t yet seen a good explanation as to why it’s associated with increased spin time.


#19

AL 6061<AL 7075<TITANIUM<AL A300
in case of their resistant

about the performance, i think not much different from one to another


#20

Could you explain what this comparison means exactly? Like why is Ti 226 - 264 and why is 7075 86 - 211. What’s the point of having the first number, and then the second?

“6061 Aluminum: 48-144 kN-m/kg
7075 Aluminum: 86-211 kN-m/kg
Grade 5 Titanium (Ti-6Al-4V): 226-264 kN-m/kg”