so Mr Bist made a comment to the Avant Garde/L4 entry that was posted in November 2011,and i asked him if he would like a write an article about it and also to clarify about who came up with what designs. so here goes:
How the Undercut was born.
Hi guys,
I notice there is some confusion about when the undercut was born.
Now I'd like to tell you the true story about the undercut shape, in my opinion the real shape of the future.
In spring 2009 I was working on a mod, named Stradivari, but as I first assembled it, I noticed the yoyo didn't work.
The holes put to much weight on the outside and that induced a lot of vibrations on the yoyo.
I had 2 solutions:
1) Start a new mod and end it till August 15 2009
2) Find a solution for solving the vibration problem on the Stradivari.
I love challenges and so I tried to cut out the vibrations.
After some day spent thinking about a solution I made the only thing that was possible.
If the problem was the outside weight I had to put some weight on the inside.
Unfortunately I couldn't cover the holes and so I made an undercut ring, that rebalanced all the shape.
I noticed that the vibrations were cancelled and the under cut rim worked like a aileron, driving the air moved by the holes.
Perfect, the mod worked!
First yoyo with undercut ( presented on August 15 2009 at the WYYC)
After that mod the negative shape (undercut) I used came to my mind very frequently, so I wondered,
what if I would design a yoyo with a forced negative shape?
In 2010 I realized the Futuro, a yoyo with a very incredible undercut
First Proto with undercut (May 24 2010)
I was really impressed by the power of this kind of shape and I realized it was the shape of the future!
After this discover I used this kind of shape for some mods, especially when weight distribution was pushed to the limit.
First Mod with undercut (29 September 2010)
Tribute to Landon (October 2011):
This is not a 100% negative shape but works in the same way
You are probably wondering about the reason of this history lesson.
The answer is easy: It's pretty funny to see fights on the forums made to determinate who made what and when....well if you don't have any documents dated before 15 August 2009, I think history books should write:
"In 2009 Mr. Bist created the negative shape, used in the years after by many companies that believed that the negative shape was the shape of future".
For the same reasons, I'd like that the "DUP", (double U Profile) designed foth Centauro shape, used by many companies, would be credited to me, unless some one has an evidence prior to 2007
10/22/2007 (unfortunately pics don't work)
But here there's a video:
9/14/2007
Evolution of Centauro: The CEN TM
5/5/2009
Regards
Mr. Bist
How about spring 2006? Is that early enough?
ReplyDeletehttp://www.hspin.com/webpage/?q=node/3653
Early for what?
ReplyDeleteExcuse me but on the Envy there aren't undercut or negative shape, the undercut is different.
On the Envy maybe there are a recess if you want you can call concave wing but not more than these.
I think Guillaume is referring to the BEYOND Envy and not the regular Envy. The Beyond has a distinct negative cut.
ReplyDeleteThis is all foolish, I understand wanting credit when due, but 'when the history books are written' ??
I don't really think they will have many words dedicated to the negative cut controversy that arose very early in the 21st century.
Just saying!
The BEYOND envy is made in 2011 and is after the Stradivari and the Futuro, is after the L4 and the AG too.
ReplyDeleteNo, I'm referring to the original Envy prototype, what's marked as spring 2006 in the link I provided. Here's a comparison with the Pyro where you can clearly see the undercut. http://www.hspin.com/webpage/?q=node/3650
ReplyDeletein the comparison with the pyro you can see only a recess or a concave wing, but there isn't and undercut and that recess don't work like an undercut.
ReplyDeleteBTW:
If you work with a lathe you can know that for make an undercut you have to change the position of the tool knife, you cannot make the undercut in one passage.
You can do the simple recess of the Envy in one passage without move the position of the knife. So on the Envy there aren't undercut.
What Mojo said.
ReplyDeleteMaybe a picture will help define the concept of unddercut when words fail so miserably (blue recess, red undercut)
http://www.asyoyo.it/index.php?app=core&module=attach§ion=attach&attach_rel_module=post&attach_id=153
As you can see on the Envy only the IRG is undercutted, the "reverse" lip has no negative angle at all.
Chris
LOL
ReplyDeletehttp://images2.wikia.nocookie.net/__cb20090506020731/yoyo/images/thumb/4/44/Lizard%284%29.JPG/606px-Lizard%284%29.JPG
And yet another recess with no negative angle...LOL indeed, you're missing the point (and its consequences on weight distribution)
ReplyDeleteChris
Hi guys,
ReplyDeleteI thought my explanation was enough, but I was wrong.
Let me explain better, please, that chocolate is different from shit. Sure same colour but what happen when you eat it?
First:
Those yoyos are modded or made with my concept of undercut, that is different from the lips of the Lizard.
Why?
Because without a negative shapes those yoyo DO not work:
http://www.facebook.com/media/set/?set=a.10150868653240265.751525.280008905264&type=3
http://www.facebook.com/media/set/?set=a.10150293645645265.493993.280008905264&type=3
http://www.facebook.com/media/set/?set=a.10150208971410265.427777.280008905264&type=3
http://www.facebook.com/media/set/?set=a.333738115264.332526.280008905264&type=3
http://www.facebook.com/media/set/?set=a.280133905264.304565.280008905264&type=3
I told you why, but probably you don't want listen to me:
I explain it better:
Let's start from the beginning:
Weight balance:
A yoyo works with the gyroscopic rules
http://www.borders.com.au/book/report-on-gyroscopic-theory/8358989/
Yoyos felling is the results of forces produced by mass, those masses spin at the same angular speed, but at a different absolute speed (centre is slow then external ring, please read a book of physical science!)
Now where and how you put this mass determinate the fillings and the yoyo playability.
There a point where masses balance the yoyo better then others, this point is here:
[URL=http://imageshack.us/photo/my-images/163/43068405.jpg/][IMG]http://img163.imageshack.us/img163/2254/43068405.jpg[/IMG][/URL]
More! this mass let the yoyo turns and give vibrations to the yoyo:
[URL=http://imageshack.us/photo/my-images/835/47534730.jpg/][IMG]http://img835.imageshack.us/img835/6917/47534730.jpg[/IMG][/URL]
So, when I had a not working Stradivari (because the holes move all the balance weight from the tangent that touches shape at 45°) I must re-put the weight in that point of the yoyo, by using my negative shape concept.
[URL=http://imageshack.us/photo/my-images/401/31799643.jpg/][IMG]http://img401.imageshack.us/img401/9596/31799643.jpg[/IMG][/URL]
Question: does a ring like this work?
(a ring like the Lizard or Henvy Proto)
like this:
[URL=http://imageshack.us/photo/my-images/600/47164366.jpg/][IMG]http://img600.imageshack.us/img600/8722/47164366.jpg[/IMG][/URL]
NO, I know because I made it, and it does not solve the problem!
Why.
I tell you guys (again!)
The ring in this way does not solve the problem, because the vibrations are not cutted, just because the weight need in the 45° tangent point was not replaces.
So, PLEASE, Those concept are different:
[URL=http://imageshack.us/photo/my-images/837/24716060.jpg/][IMG]http://img837.imageshack.us/img837/8764/24716060.jpg[/IMG][/URL]
You still think this shape has been created before? Ok so, please reply to those questions:
Why no one went on with the Lizard project?
Why all the project close to Lizard died?
Why company started to produce the negative shape after seen mine Cen4?
Why L4 come out after mine?
Why YYF come out after mine?
Why with my negative shape yoyos work better, and with the lip at 90° does not work?
You still think is the same concept!
Ok, it is, just like quad skating are In line skating (rollerblade), or a biplane is the SU-47, some one would say "Sure they are both plane!"
Unfortunately this concept is not easy if you had not tested it, that's probably why, after a page of explanations someone still quotes and will quote the Lizard!
Now I explain you everythings, why, when and how, now please ask to Ben or L4 why they made it in that way.
Probably answer would be "Ehm...something about the weight".
The only one that understand the power and importance of negative shape is Xcube, that's why his yoyos work so good.
Regards
Ettore
(man once known as Mr. Bist)
Links to the pics don't work I think, here you can see pics:
ReplyDeletehttp://www.asyoyo.it/topic/4039-scusate-se-uso-il-forum-per-scopi-personali-ma-devo-vedere-che-le-immagini-siano-giuste-bannatemi-ce-chi-e-stato-bannato-per-molto-meno/