first robot

thanks, they seem pretty cheap and look decent enough.
thinking about getting two of these: http://www.electronize.co.uk/FR12VR_spec.htm
now i just have to search for some good batterys for the motors and buy all the parts and start planning my design.

For batteries, I would also suggest the Vapextech range mentioned above. I have had problems with them in the past in terms of some cells burning out but that was because I was drawing more current from them than was recommended. All the other times I've used them within their limits, they have performed very well.

Using them to power two scooter motors will not push them beyond their capabilities so should be adequate enough for your robot. So for 24V motors you will require two packs of 12V wired in series and, as mentioned, to last a fight or two you really need a 'mAh' (milli-Amp-hours) value of 3000mAh or above. These ones:

http://cgi.ebay.co.uk/12V-3700mAh-NiMH- ... 3353ee4e1a

are 3700mAh and should last at least a couple of fights. Doesn't sound very long but this is the nature of combat robotics. Those packs are also £27 each, which is £54 for 24V. It may seem expensive but you get what you pay for, and these batteries will do a good job.

Best of luck with the design/build and make sure to get some pictures of it up once it's taking shape if you can :)

when you say to wire them in series, do you also mean that both motors will draw power from the same 2 batteries?
cant wait till i get the parts now and start building it :rofl:

That's correct yes. Both battery packs have a negative (black) wire and positive (red) wire. You connect the black wire from one battery to the red wire of the other and then you are left with an unconnected wire from each pack. The voltage from these wires is now 24V. You connect both your speed controllers to your battery wires in parallel (i.e. each speed controller has one red wire and one black wire. You connect the two red wires from your speed controllers to the unconnected red wire from the battery pack and the same for the black wires). This means that both your speed controllers will get 24V and therefore both motors will get 24V.

ok thanks for clearing that up, was getting woried when i thought it may cost me £100 for 4 :)

Haha, no two packs will be enough to get your robot running. You could by another two packs to have as a standby pair so you can swap one pair of packs out when they're flat and put the standby pair in, but that would mean spending £100 as you said :)

However, chargers are pretty good at either slow charging (about 20 hours) or fast charging (~30 mins) so a fully-charged standby pair is more of a luxury than a necessity. With fast-charging, you can go through an event just using two packs without any problem.

thanks for the help so far, but what is the best material to build a featherweight frame out of?
also what would be a good choice of weapon, i want something simple for my first robot but im not too sure if a simple wedge would be able to do much?

It depends largely what sort of power's in the wheels behind the simple wedge, just ramming people can be and has been used as a great tactic and I'm told pinging other robots off the walls at 10-20mph is quite fun :proud:

For your very first robot I would advise concentrating on getting the drive working reliably before thinking about weapons, if when all the construction is done and it works you have weight and space for a weapon I'd add one if you feel comfortable with it. Spinners would probably not be advised for a first build and neither would anything with pneumatics, unless you have a good understanding of valves and forces and the parts required, so an electric axe or lifter would be a good beginners' choice should you find yourself with weight and space to spare :)

ok thanks, il put together my drive system and see how much it ways and what force is behind it before i decide on a weapon.

hdpe is quite good for internal frames

box section and metal skin

or wood :talker: ie block of wood

wood is good :), some woodend bots have done amazingly well. My 4 kg wooden but survived more than 5 goes on teh arena flipper before the wood split.

well not to boost or anything but block of wood came 4th at 07 fw champs

plus armour cost £15 for 2 sets of armour :talker: :talker: :talker: :proud: :proud: :proud:

sounds like wood is proberly the best options, it will proberly be easyer for me to work with also.
im just going to wait untill i have the motors (xmas present), and then make some designs for the robot.

sorry for asking questions, but i cant figure out how i will connect the one battery i will have after conecting two together to 2 speed controllers?

split the negative from the battery 1 to each speedo and take 2 positives from the link 1 to each speedo ... job done also take another ngative from the battery to your power light and a positive from the link to the power light too ..... :talker:

ok thanks for the help, il get my dad to help with that part.

nt sure if its any help but...

just to explain jacks diagram, its a 2 dpdt switch setup to drive 2 drillmotors very very cheaply, it works amazingly well and only costs about 10 quid.

i used to use this set up in our first feather always worked well and very cheap and unlike a speedo they dont blow up :):):):):):

ah ok i think i know what it is now.
so with this setup i wont need a speed controller?

no but you should match your batteries to your motors to keep the speed realistic as they will be full on or full off in forward and reverse so you need to make the speed enough to be drivable .......:) :) :)

ok thanks seems like it will save me some money :)
would these switches work?:
http://cgi.ebay.co.uk/4-x-DPDT-Mini-Sli ... 439bd06a05

I thought it was microswitches, sevos and relays that were used to give direction control?

im kinda confused about these switches. would it be best for me to buy speed controllers if i can afford them?

Its always best to buy a speedo if you can afford one ..... I used servo's and micro switches because the robot they were in was designed to be smashed up for the crowd so nothing exspencive went into it but they work well ......

ok i think il go with speed controllers, do you think two of these will do fine?:
http://www.electronize.co.uk/FR12VR_spec.htm
they are £32 each.

i would highly recamend getting a speed controller, cos although dpdt switches/servos will work ( im using them in my 4wd axe bot) speed controllers give better control and can be used for other robots later. buy somthing good now and it will pay off in the future :)

Those will do you fine. Been using them for years. Tried a couple other controllers and have found the electronize to be far superior due to their simplicity, ease of use, cost and current handling. Went back to them after a sabre tooth and sidewinder.

thanks, im going to start ordering the parts tomorrow. probably would be best if i check everything is running the way i want before i start designing the base.

i found some cheap lead acid batteries but are they allowed in the rules?
these are the batteries:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT

yes they are allowed bit heavy but will do the job fine

ok thanks, just wanted to check. il proberly buy them to save me £30.

You can use SLA (sealed lead acid) batteries but I can't think of many if any current featherweights that do. They are heavy and in sizes suitable for featherweights can't deliver any decent amount of current.

I'd save your cash and go get some Nimh or Nicads. It might cost a little more but its well worth it.

thanks, i might get them just to get my robot going because i want to spend more on other parts of the robot and get the better ones later. if i did that i could always keep them as a backup incase anything goes wrong before an event.

I used to think in exactly the same way with robots. So you save 30 quid just now and get things moving and limit its performance. Or spend the 30 quid extra just now, wait a little longer and get a machine with a far higher spec and you will save a lot in the long run.

It's ultimately your own decision, I'm just trying to save you time and cash in the long run from my own experience and wallet.

nicad and nimh battery packs are very good for new comers i would say

i did start of with an sla but it didn't hold charge well and so i progressed to nicads

also a point to think about is sla's are very hard to sell on, where as i think i would fine it easy(ish) to sell so i could buy some a123 cells for example

for my very first bot i spent the smallest amount of money i could , all fo the aprts i bought have now been replaced, but i wouldnt of done it anyother way, i used 2 argos drills and used the batteries out of them and 2 wuper cheap rc car speed controllers. it was awfull but i gained experince no amount of asking questions could have got me, so for your first bot go cheap, itll be rubbish but you will get into the arena and have a bit of fun:).

thanks for the advice, i have already bought the cheaper batteries and im just waiting for them to come and il test my motors out then buy everything else.
for the wheels im thinking of buying 2 rear wheels from a scooter which has a gear thingy (duno what you call it :p) so i can attach a belt from my motor to it so i wont have to attatch them straight to the motor.

personally i think your over complicating thinks, get some bluie wheels from robo challenge staright onto drill and they are very grippy and i haven't had a fail from them yet

btw if it is a gear on the wheel a belt wont work


also if your looking for some more batteries in form of drill batts i hav taken delivery of some new drill motors and don't need the batteries come with chargers aswell 2x12v packs

????

thanks for the offer but im going to see how the motors i got work out.
the wheels are:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT
i was thinking of getting the belt for it and attaching it to the motor?