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**Guest** · 27 April 2004, 20:43

FBS braking + link system????

Hi Grant,
I dont have any personal experience of FBS but one potential problem i can see would be if the servo mechanism was damaged during a fight and did not engage properly it could be very serious if you stick your fingers inside to remove the link and the locking pin fails before power is removed.

Im sure someone better placed than me to talk about event safety will put a better answer up here at some point but i could not see many events allowing you to pass a tech check with this system in place.

**grant_ploughbot** · 27 April 2004, 20:52

FBS braking + link system????

yer that was my tought, even tho my lockin pin will be hand removed, i can locate it in aslong as the disc is not goin very fast, but the servo mech is a possible hazard!
Grant

**typhoon_driver** · 27 April 2004, 21:01

FBS braking + link system????

Grant we have to use large bearings on all our robots to allow us to get a link in.

The feather weight alone uses two 500g bearings which are completely oversized but we need that to fit a flag down. These are the same bearings used in the middleweight.

It is a real pain in the **** but I cant see anyone being happy about a servo mechanism working before the link can be pulled. Sorry to be so bleak!

Would u be able to fit a few wires capable of holding the current down ur shaft? That way, u could perhaps have the link on the very top of the robot and attempt to connect it in such a way that it doesnt spin, crazy idea but one of the only that i think you could use to get around the link problem.

**grant_ploughbot** · 27 April 2004, 21:20

FBS braking + link system????

Yer i think i will have to re make all the centre axle then, its only (dont laff untill u herd the rest) 10m axle, BUT..... it doesnt even need that centre axle. it has 7 outer bearingsalong the outer rim to cause minimal movement, and a further 3 around the top so there is no movement, the disc can be safely run withough the centre axle.
I have thought about having a link that is able to rotate, but it seems VERY complex for what im capable with the facilities at school, I am realy impressed with how it has turned out, up until i realised i had to put in a link :sad:
Oh and gary, where do you get those bearings from, and what are the dimentions and prices as i think this may be my only way around it.
If possible could you please email me at coop_bmx@msn.com on how you flag/link works with bearin stats?
Thanks very much for your help!
Grant

**typhoon_driver** · 27 April 2004, 21:37

FBS braking + link system????

so there is no movement

Im not sure that that is a wise idea, it is best to allow some degree of movement in ur disc even if jst a few mm so that not all the of the shock is taken by the bearings around the edge, so perhaps some shock absorbers?

We had the same idea as urself in extreme 1 with the middleweight however the small wheels that we had around the chassis were to absorb the impact and keep the disc spinning correctly so to speak. After 1 five minute battle, all of the wheels were bent or buckled out of position. True they were only an afterthought and werent very strong but still u might want to a have a slight bit of give somewhere.

Ill find out about the bearings and get back to you, although im not sure when that will be.

**grant_ploughbot** · 27 April 2004, 21:43

FBS braking + link system????

Okie thanks, well i have an idea for soft small wheels around the outer rim, but i fized with the idea of bearings, but if thats the problem you had then i will change my ideas bakck to smaller shock obsourbing wheels.
Thanks for your help
Grant

**julian** · 27 April 2004, 22:12

FBS braking + link system????

Perhaps for FBS the rules could be relaxed. The link is needed for the certainty of it being dead outside of the arena and for being retrieved whilst being nominally dead in the arena.

However, who in their right mind is going to go within a mile of a rogue FBS, let alone try and reach over it to pull out the link? You let the batteries run flat. Anything else is dangerous.

**Guest** · 27 April 2004, 23:49

FBS braking + link system????

Still needs a link though, if for no other reason than to stop it spinning up before you want it to.

**julian** · 28 April 2004, 00:42

FBS braking + link system????

Still a link but it could be allowed to spin on the body, ie would not be available when spinning.

**grant_ploughbot** · 28 April 2004, 10:00

FBS braking + link system????

Well i will still have 2 seperate links, one ontop, and one underneath incase its flipped over.
Just my top main link will be underneath the disc, altho i have prcedures to stop the disc spinning!
I may need to rebuild the centre axle but i have also toyed with the idea of having an underneath link like mauler, just very unreliable.
Grant

**jamesb** · 28 April 2004, 13:15

FBS braking + link system????

I think the main thing is that it is bloody scarey removing a link in a full body spinner even when it appears to be fine after a fight. I for one would not want to turn the thing over while its still live to get to the link!

Also, Ive had damage to mine and when I pulled the link it span up! how? well, the wires had been crushed to the body by a vertical crusher (mentioning no names cooper snr) and the pull on the link was enough to short the wire to the body which was used as the negative of the robot, like in a car, and like in Mute. The moral there is, if the link had been on a part that spins Id be typing this with missing fingers.

Just my bit of input, we can have a chat about the FBS at my house warming if you want Grant.

Cheers

**mute** · 28 April 2004, 13:28

FBS braking + link system????

James,

The moral of the story is if you are using a negative earth chassis, then use heavy duty insulation on your wires.... like 170A truck motor starter cable

The insulation on our stuff is TOUGH, so tough that we cut it with a hacksaw - a stanley knife barely marks the stuff.

Why do I get cold shivers when someone mentions Mute and short circuits in the same sentence???

**fluppet** · 28 April 2004, 13:30

FBS braking + link system????

Julian: Call me a wimp, but the idea of relaxing safety restrictions for full body spinners (especially on the grounds that theyre too dangerous to go near anyway) doesnt appeal.

If a robot goes nuts (in the ignoring-remote-kill sense), it probably needs stopping before the batteries go, if only for the sake of the arena. If the accepted procedure is to pin it against the arena wall (with a house robot, in the Robot Wars case) so the link can be pulled, Id be a lot happier with the concept of pulling it out if the thing cant suddenly wrench my arm off should it slip free.

Mind you, presumably most of the time its a problem for the owner, and since I dont intend to build an FBS its not my problem!

--
Fluppet

**jamesb** · 28 April 2004, 13:48

FBS braking + link system????

Hope the reference wasnt taken with offence Daniel, simply adding a respected name to the post as no doubt there were responses of well what a stupid.... on the way if people didnt realize that I wasnt the only one to do this.

For me, if a hypothetical FBS of mine goes out of control (even a 12kg one), Im switching the controller off and waiting for it to fall asleep. Any talk of me going in with it to pull the link will be met with laughter. I would say that for all spinner actually, if I built it, chances are its whip your hand off, so I aint feeding it bits of me thank you very much.

As I said, pulling the link on a perfectly (apparently) fine robot with juice still in the batts is nerve racking enough.

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