Simple first bot.

Hello, I made a thread here some time before crimbo '09 preparing to build my first featherweight. The idea just kind of died, as money was an issue and it never really took off. I've learnt alot since that old post so here are my plans for a bot, this time for real.

Remember, this is my first time building a full scale (it's a feather, but you know what I mean :P) bot, so cheapness and simplicity is a must!

Right, here goes:
Starting from the bottom up, I'll hopefully be using 4 rollerblade wheels. They're robust and are pretty grippy.

For motors I'm pretty set on 4 of these: http://www.argos.co.uk/static/Product/p ... +DRILL.htm (WOULD LIKE SOME OPINIONS! :uhoh: )

I am not sure howmany of these ESC's. I'm guessing two, two being maximum really (price!): http://www.electronize.co.uk/FR12VR_spec.htm (Probably mean I'll end up with 2 motors and 2 wheels, lol, oh well)

For chassis there are loads of local railing and window frame-like builders around, this shouldn't be a problem. Likely to be heavy though.

Pretty much the same story for a shell. Although since this bot won't be for competing, I probably won't bother.

This radio system: http://www.sussex-model-centre.co.uk/sh ... p?id=29064 (cheap, recommended, 2.4Ghz, what more could you want? :P)

Hmm.
What else? I think that's about it. I plan to make a very powerful box. 2 motors is kind of not what I wanted, maybe someone could recommend some more powerful motors that would work with 2 ESC's within the £60 price range? (30 each) if not just throw anything at me lol. :D

I think that's about it.

P.S. are ESC's REALLY necessary? I mean, either full pelt or nothing will be pretty awkward, but for a test... ?

Thanks in advance,
Ellis

yeh there is little point in making a combat robot with no speedos :)

you will need a max of 2 speedos its one esc per side so you can have 4 motors on 2 escs

all the links are fine, but i would recommend a dual speedo bit more modern and give great responses

any cads or owt???
alex

Ok, thanks for the heads up.

And not really, no. Just imagine a remote control shopping trolley and you're pretty much there. :D

Here's a hint, this hobby WILL cost you money. For a standard featherweight rammer, you're looking at around 150 to 200 quid and believe me that's cheap! That used to be the price of a transmitter alone!

I can understand trying to make something for nothing but if im being honest if you want to have something of any use in the arena one day then it's better to spend a bit of cash now and get some usable parts.

O and don't worry about the electronize being up to date been using them for years no bother with drills.

I am expecting aroung 150-200 anyway, and I live in Spain so it's very unlikely I'll be entering any comps any time soon. :(

Maybe I can start my own thing over here. Various friends of mine are massively interested in anything that goes BANG.

So this list is about right? I can start ordering now you think?

Going on what you've listed and what you'd like, here's a possible option:

The speedos you've linked to don't have a high enough rating to run two drill motors each, so 4-wheel drive is out of the question. But what you can do is put 4 wheels on your robot but only connect two of them to drill motors. If you connect the two diagonal ones to drill motors you will have something that is not too different from full 4-wheel drive in terms of handling but which only requires two drive motors. That way, you can keep the cost low with the speed controllers and, if you buy four drill motors, you'll have two spare motors.

Are speedos really necessary you ask? Not at all. The full-pelt or nothing method of using micro switches operated by servos to control your robot will do the job. Not the nicest job, but they will allow you a degree of control over your machine. Driving 2-wheel drive robots with switches can be difficult but with a 4-wheel diagonal drive setup it is a bit easier, as the two idling wheels give a little bit of friction to prevent the robot from spinning wildly when you turn and also help to keep it going in a straight line.

Ancient video time!!
This video illustrates the idea mentioned above. It's got four wheels (well, was meant to, but only has three, lost the other one :lol:) but only the two diagonal wheels are driven by drill motors. Control is provided by micro switches operated by RC servos:

http://s31.photobucket.com/albums/c367/ ... t_0001.flv

Hm. Okay, well, could you link me to some suitable speed controllers? I want 4 motors and will do pretty much anything to have them. :twisted:

I'll get ordering everything tomorrow, for now, bed.

it would have to be i think (not sure) a dual speedo but with that you need to make sure that each channel can take the combine stall current of 2 drill motors

Hi, firstly let me say by no means am I an expert I have only just built my first robot. I too wanted to use 4 drill motors and had the burning question of which ESC to use. You may find the descussion in my thread helpful [ur=http://www.fightingrobots.co.uk/forum/viewtopic.php?f=164&t=3000l]here[/url] for a number of options.

For me I found that things most people where suggesting where about £100+ and there wasnt a general consensous they would certainly work. In the end I went for a Wotty100 which set me back ~£180 back. There is the also this which is very similar in both spec and price.

For me anything cheaper wasnt really worth the gamble of blowing £100 speedo when i stalled the robot.

Well, ok, I've gone for two of these: http://www.electronize.co.uk/model_elec ... frames.htm (FR15HVR). If anyone strongly objects, please do so ASAP, I'll probably be ordering them tonight.

I am going for the Planet 5 2.4Ghz transmitter and reciever shown above.

I've gone for the slightly more expensive ESC's because the drills I was going to get don't get delivered to Spain, and they don't even exist over here. I'll be going tomorrow after school to check out some cheap drills locally. It's just on all the websites I've visited, they've been pretty expensive.

Oh and I know it's possible these two ESC's won't be able to run 4 drills, I might end up having to settle for a 2 motor bot :c...

Which is still ok, since I'm not going to be entering anything for now, lol.
Thanks for the helpful comments guys, much appreciate 'em.

I think they should work for two drill motors fine but I very much dout 4

Sigh.

Okay, well, I guess that makes things a good deal cheaper. I'll over volt them for the extra bit of juice. Thanks.

you could always run a pulley and belt between the wheels on each side to give you 4wd on 2 motors.

I think you will be surprised at the power that 2 motors have.

Well, after speaking with Grant (thanks!), if I can persuade my parents just a bit more, I'll be going for the 30A ESC, not the 15. This should run 4 motors ok.

We'll see. :?

Bought the four drills today, ordering the ESCs and the Transmitter/Reciever set tomorrow, will have access to some chassis-like material next week aaaand I couldn't be happier.

Might start a build diary.

The ESCs just arrived, the radio system should be arriving on wednesday or so. Once that arrives, I'll test out the setup and get to work on a chassis. Still need wheels.

http://web.me.com/robochallenge/Robo_Ch ... nical.html

These have been battle proven many many times.

Yeah, I'll go for blue wheels if I can't find or use anything I can get locally. Seems a little silly to spend more and have to wait to get them when I'm sure I can get something cheap locally.

Thanks.

another option is these http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT

Bought some recently as I needed 8 cheap wheels for a project. They aren't as grippy as the blue wheels and you would have to get a hold of some nuts to fit the thread on the drill yourself, heat them up and press them in but they might do the job.

Transmitter and reciever have just arrived, it's a little confusing at first, what with the instructions pretty much saying this is the reciever with no real diagrams or information. After a good look though, my dad and I (I'm off school today, knee problems) hope to have atleast one motor controlled.

Am chuffed!

Thanks for all the help, with probably need alot more in the future. :D

Another update.

We managed to get 2 motors running on seperate joysticks, very happy, the speed controllers work perfectly, we had no problem binding the reciever and transmitter, it all went, quite worryingly, to plan.

Except one thing. The Planet 5 transmitter we bought, the right joystick (could be left, depending on mode) isn't sprung, as in, it doesn't center itself. This is a problem, as bringing the whole system to a stop is quite hard, and if not done perfectly, two motors will be grinding because the speed controller is making them creep unless the stick is perfectly centered. We considered taking the spring off the left side to make things even, but it's really not ideal. I was wondering, if anyone has ever bought this radio set, how did you do it? Did you just get used to it or have you managed to bodge it, if so, would you mind showing how? Thanks!

Ideas are appreciated, we've had a good look on the inside of the transmitter and there are a few things missing to mount the spring onto.

Also, what would you recommend as armour? We plan for a sheet of steel, is 3-4mm alot? I was originally planning 7, but after redesigning the shape of the thing a little, there is no need for such thick armour. We still need wheels, most of the things on Ebay are UK postage only, and the ones that are to the EU are generally shopping cart caster like wheels, not ideal.

Thanks!

Ellis

Think you will find this with all transmitters as they are designed for flying and the left joy stick is the throttle so isnt sprung. I have both motors on the right joy stick using the chanel mixing, so you control it like using a remote control car. Alternativly I think you can remove the spring from the cradle that returns the sticks left/right movement and it attach it to the vertical axis.

Yes, we've considered that also, thanks for the suggestion, still thinking.

If theres space, 2 rubber bands, one going one way, another going the opposite, might do the job enough for it be nice to use.

you might be able to find a spring set for it on the galaxy models website.
http://www.galaxymodels.co.uk/

Buy yourself a V tail mixer ...then you can drive on the one spring loaded stick.

eg http://www.allelectricrc.co.uk/gws-v-ta ... 1323-p.asp

galaxy is a really good place and the speedos aren't that much.
i asked the people ant they said you will need to get a marine speedo because they are the best ones for robots with 12-18v motors.