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Ultimate Rim Weight Experiment - The Fulvia Series


I flew into Hong Kong to visit with my parents just over a month ago. It was their first time back since they left Canada almost 40 years ago. This place has changed so much so, they couldn't even recognize most of it. And although it was amazing experiencing their home town with them, I was focused on a new goal after they left - to attempt to create a yoyo that has been a "what if" thought for a very long time.



The argument of rim weight has been around since I picked up a yoyo over 10 years ago. Some argue against it - saying that it makes a yoyo feel sluggish or heavy. And others stand by it purely from a performance standpoint. 10 years ago I didn't have the skills or funding to find out what would happen if someone engineered a yoyo with an absurd amount of rim weight. But now I am positioned to find out - and 4 months ago I submitted the CAD files and started a little experiment. The Fulvia BTM-R.



The name BTM stands for Bi-metal Titanium, or simply Bi-tanium. A titanium yoyo with the use of other materials. The R as you likely know from previous releases is for "Raw". Titanium is used because it can be machined wafer thin, and although it is heavier than aluminum by volume its absurd strength means you can use much less for the same task. With the rings, brass was considered but I decided to chose a 316 stainless steel for its ability to stay beautifully tarnish free.



Some companies in the past have attempted huge rim weight before. In my past experience, the Swiss designed Hspin Envy and the absurdly cool Yoyfactory Catch 22 stood out. Both of these yoyos had massive amounts of rim weight achieved in very different ways. Hspin used an aggressively H-shaped profile and the Catch 22 used thick titanium rings. Both released in eras where yoyo design/prototyping was less assessable compared to now a days, which made them all the more impressive.

Of course I couldn't write this article without the mention of the Draupnir - the modern day favorite when it comes to rim weight. But what the others did wrong, the guys at Yoyorecreation got right - the overall weight. In the past, rim weighted yoyos did not compensate for how heavy it felt. A yoyo essentially feels heavier when it needs more energy to spin up - and consequently slow it down. This is a perceived weight. Though the Draupnir weighs a measly 63.5ish grams (almost 4 grams lighter than the Envy and Catch 22!) it can keep up with anything you throw at it, including national level contests around the world. The perceived weight of the Draupnir is closer to 66 - 67 grams making it much more comfortable and quicker. It was clear they understood what I am going on about. 



But designing a yoyo has always been more of an art than a science. Any large manufacture will tell you this. We make a prototype, with our best educated guess on how it will feel. Some have spreadsheets to help, some take measurements from previous models or look at Moment of Inertia values. In the end the feel of the yoyo can never be guaranteed. I used this method in the past, but when designing for maximum rim weight, how it felt no longer mattered. With this project it quickly became a numbers game.

All Luftverk products have at least one sometimes two sections of the yoyo absurdly thin, around 0.5mm. If you compare that to aluminum, the recommended minimum thickness is something like 1.2mm - 1.4mm. In previous models, I usually place the thin segments in areas where weight will cause the yoyo to feel sluggish but have less performance gains, such as mid-center area. With the Fulvia, it was much simpler - make every section of the titanium hub as thin as we dared without compromising too much strength. And then make the rings weigh enough to meet the target overall weight.

This thought process made it really challenging to machine. When we first tried, the thin walls were actually being bent by the cutting head - so slowing down the machining process was a must. Basic simulations had to be done to solve this issue and reinforcement was added in crucial areas. This is literally as thin as possible while still minimizing risk of machine failure and final strength. Another issue was keeping those massive rings concentric to the bearing post. After 9 prototypes, we finally developed a method to machine almost 90% of the hub in one go without dismounting. It was one of the key points that made this possible. The other is my personal assembly methods. I assemble and polish each one myself, with some weird techniques that not even the machinists know. I don't think they were really interested in learning once they saw how much time was involved, but it also means only I can make these unique yoyos come out playing smooth.

And this is the result. A wafer thin shell - thinnest point is 0.45mm as you near the ring, and thickest point 0.7mm near the response area where weight savings is minimal and bending will most likely happen. On a throw, you can actually hear how thin the titanium is, it has this weird hollow hum. The hub weighs around 10.2 grams, where the ring is 20 grams nearing twice as much. The total weight of the yoyo is 63.3 grams. I am proud to say it feels fantastic, extremely fast and light but with high amounts of stability and spin time. Very different to any other Luftverk product created.

Luftverk Fulvia Cross Section

And as an addition, I decided to produce the Fulvia R (pictured below) which is a standard titanium version without weight rings. A lot of what we learned from manufacturing the BTM-R went right into this mono-metal version. As the cross section shows, the weight distribution is slightly different with thicker walls to make manufacturing easier/more affordable, but there is still a huge majority on the edge. Although the R and the BTM-R weigh roughly the same and have the exact same profile, they certainly feel very, very different.
 
So what is the conclusion? Is there such thing as too much rim weight? Will mid weight feel better? Well as all yoyos go, it is a super subjective thing on what feels better or what plays better. But I invite you to be a part of this experiment. Both these will eventually be available at the Luftverk store. I want to hear opinions. I want the lucky few who will can obtain both to share the yoyo. Bring it to contests, let people try. And report back. From a competition performance standpoint though - both trump everything I have ever produced, hands down. Its also the first time I've felt burnt out from manufacturing a yoyo - Its been a long journey to get here, and I hope it is well worth it for you.

Fulvia BTM-R - 510$
Fulvia R - 290$
Pre Order - Tuesday 31st @ 9:00PM EST


 

 


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