BOBSI? BOBS? What was it?

[Vahur]

Hello!
Thanks for new forum setup, hopefully now I can see pictures more easily, in old forum Mozilla didn't show linked pictures and I had to launch IE for seeing them :(

Now question before old forums will be lost: some time ago (1 year? 2 years?) someone invented method to measure board stiffness by measuring its camber before and after loading. Has someone link to this thread any more? I'd like to measure my setup and compare it against other boards, but can't find this thread by search engine (can't remember, how it was called...)

P.S. Why this message box is so narrow? In my browser (Mozilla) I can see 32 characters only in a row....

[NateW]

I think I remember that thread...

Bomber
Online
Board
Stiffness
Index.

Sorry, no link, that's from memory.

[Marker]

Yeah, Nate is right, it was definitely BOBSI. I am of no more help than that myself though.

[Chris Houghton]

I still use it for evaluating board stiffness, my preference is the later version that used the length in the formula as well as the deflection under weight. Using a 10kg weight, and measuring effective edge in cm., deflection in mm., the formula can be simplified to

(98.1/deflection)*(effective edge squared) = BOBSI

The numbers for Maciek's "serial" (read production) boards always seem to come out around 9 to 11, I've measured Burton, F2, Hot, Burners, Oxygen and others. Customs generally are stiffer, and yes you really can tell the difference in 0.5 on the measurement system. OF course it does not know the flex pattern, so a stiff board with a soft nose would just be weird.

Good luck, and have fun with numbers!

[Derf]

Originally posted by Vahur
Hello!
Thanks for new forum setup, hopefully now I can see pictures more easily, in old forum Mozilla didn't show linked pictures and I had to launch IE for seeing them :(


I also use Mozilla. What I did for the attachments was change the "%5C" in the url to a "/".

Derf

[Vahur]

OK, now I measured BOBSI of my board. I'm not quite sure, whether I did it correctly (effective edge means that board should be placed so, that support points are on effective edge 'edges'? And effective edge should be in meters instead of cm? ) but after fiddling with 102 CD-s as weight :D and number crunching I got result 11.6 for my 162 cm. Silberpfeil with Conshox. Seems like it is on stiffer side then. Probably thanks to Conshox. I'm too lazy to measure it without Conshox...

[george]

I think we need a similar formula for ranking trench depth and length. Something like depth * effective length/radius should do it although I fully expect the maths geeks to point out where I've gone horribly wrong.