fbs's

hey all

im designing a fbs along the lines of:

http://www.youtube.com/user/rctennis.../1/VLV1AV1TI6w

and im wondering how i can incorperate the required power led/removable link. im looking at the typhoon (ish) method for the link (deans connector on the chassis, other one connected to the flag) but for the led im well and truly stumped, perhaps can have the led on the inside and drill some holes in the top of the shell so the led is visable? how do other fbs do it? thanks in advance, jack

The best way to do this is to have a tube through the middle of the robot that it fixed at the base plate then run wiring to the link and power light up the inside. Then have the spinning shell spinning around this central tube. Best example is the new little spinner.

how will i attach my motor to the shell?

http://www.rampagingchariots.org.uk/typ ... robots.php

This method of attaching a disc assumes that you are not directly mounting the disc to the motor, which I assume Jack, you will be doing as its a kilobot cos you'll just want to screw it to the brushless motor.
The way you said with the LED, drilling holes in a circle around the top so its visible when spinning has been used in antweights before, you'll have seen MBY, this seems to work fine. As for the link, I think you can make it accessible via the base, like Dizzy Tilly does. As it's only a kilo robot, and it'll have failsafes in it anyway, I don't see why you wouldn't be allowed to do this if a featherweight is.

Don't attach a disc directly to a motor. It may work fine in the antweight class (I'm no expert on this) but unless your motor has a decent 10mm plus diameter shaft you are going to snap it, especially in a FBS. You need to machine a seperate shaft and then using a belt and pulley transfer the energy to the disc shaft.

even in a kilo machine I can see the energy and forces involved getting silly and believe me when it comes to FBS you do not want to screw around.

Gary, most of the states FBS's kilobots and beetleweights just use a standard brushless motor shaft, which screws directly to the motor. I've never known anyone have a problem with this unless it is unbalanced, including myself I must say. I've had my brushless motor shaft spinning a load that weighed a kilo on its own without any problems, so I can't see a problem if the whole robot weights a kilo.

Most of these shafts are about 2 - 3cm, but I have also seen people attach the disc to the actual body of the brushless, which also spins, with great success.

I reakon this is one weight class where maybe experience with antweight and superant technologies will be more handy than any of the higher weight classes.

An alternative means of driving the body from the brushless motor could be friction. I have no idea where to find the video but I remember seeing an American FBS (one of the light weight classes, but not as high as feather) that spun its shell up using two brushless motors with small rubber wheels on them that made contact with the underside of the top (it was a hockey puck style FBS rather than cone-shaped, Typhoons etc). The spin-up time was minimal and it performed like the clappers. With this method it's a bit more lightweight and perhaps easier to fit in a small robot than using a belt and pulleys. Plus you've got the added bonus of it acting like a clutch to allow a little slippage if you hit an immovable object.

I've seen friction-drive Beetleweight spinners too Jamie. I believe ring-spinner T6 works on friction.

http://www.buildersdb.com/botdetails.asp?botid=6346

Lol if theres one thing I know its FBS. If you wanna go strapping a disc directly to a motor then by all means but a few mm shaft WILL bend after the first collision. They are designed to support props from aircraft or a pinion gear for a gearbox. Any shock impacts will take them out, and if the shaft doesn't bend, the magnets may well shatter.

Doesn't Tony directly attach his discs to the motors in some of his featherweight spinners?

Not as far as I'm aware. I believe he may have 1:1 ratios running from motor to disc but that way the chain or belt may be more likely to snap than the motor shaft.

Id listen to Gary he knows what hes doing. Hes had more spinner experience than anyone here.
Im doing a FBS kilobot and I wouldnt even think about mounting my shell directly to the motor. Think about the impact when 2 FBS's hit eachother.