Torrent's build diary - a dream coming true!

[MudnuK]

Without experience, and despite my best efforts to find out myself, I have to ask what sort of peak can I get away with?

[plargen]

well my estimates were that my drills pulled 25-30a peak so about 120a max for 4 motors so i looked for something with a higher burst current and the turnigy seemed to give a good burst amp (157a) and there very small and i can do 2 fights on 1 battery

what voltage are you going to use

these are the 1s im using
http://www.ebay.co.uk/itm/Turnigy-Na...item20d1109686

[MudnuK]

Thanks. Just wanted to know what to look for, but I'll probably end up going for anything that's tried and tested anyway.

[MudnuK]

Sorry Plargen, I didn't see this. I'll probably use 12v drill motors from B&Q or Argos, but I might go with two wheel drive so the wedge works inverted, for which I'll need more powerful motors (maybe Gimsons)
Does it make sense to make a robot designed for a weapon, and upgrade it by putting the weapon in later (which is the preferred plan), or by making a simple starter bot and make a whole new bot with a weapon?

[typhoon_driver]

gimsons are drill motors

[plargen]

the argos motors probably wont be to different in torque the main difference is the build quality looks/is much better on the on the gimsons units

[MudnuK]

oh ok. So what would I need for two-wheel drive? Otherwise with four-wheel drive I need two different-sized pairs of wheels and have to do something tricky with gearing or the ESCs.

[plargen]

2wd will be the easiest by far, between the argos drill and the gimson units it depends mainly on how much you want to spend and the gimson units should be more reliable and you wont have to over volt them to get a good speed if you go for the 24-1 gearbox

[typhoon_driver]

"gimson units should be more reliable" - Debatable.......

[MudnuK]

At last I've actually done something! I bought a couple of cheapo Argos drills today and have removed the motors using Ellis' tutorial video (very helpful!)
Over the next month(s) I'll start buying all the bits and pieces I'll need and Torrent might will start taking shape! Finally I feel like I'm going somewhere.

On a trivial little side note, I met the son and wife of the man who built and competed with Demon Duck today, which was interesting.

[Porker]

What batteries are you using?

[MudnuK]

Batteries are where I struggle the most. Plargen says he pulls around 20-30A per motor in Night Fury, and I'll be using 2wd, so that should be around 60A peak. I'll aim for the 75 to 80A peak mark. I was thinking of going for something like 2650mAh with a 30C peak. Does that make sense?

Trying to redesign the shape of the robot. What are the effects of having one motor + wheel in front of the other (as in MoBot)? It would allow me to have sloping sides which would be beneficial and look cooler.

[Porker]

Okay, thanks.

[MudnuK]

Sorry I wasn't very helpful. I'm new to this whole engineering and electronics scene.

[RogueTwoRobots]

What are the effects of having one motor + wheel in front of the other (as in MoBot)?

You get a good balance between the characteristics of 2WD and 4WD.

Conventional 2WD with the wheels/motors in line with each other is a very agile setup, but sometimes when driving in straight lines, your robot can have a tendency to veer off to one side or the other (multiple reasons, such as offset weight distribution, one motor turning faster/slower than the other, part of the chassis dragging on the surface).
Standard 4WD is good at going in straight lines as there are four wheels in contact with the ground which adds resistance, helping to prevent your robot from veering off. The drawback is that when you do try to turn the robot, that resistance is still there, so it doesn't turn as quickly as a 2WD machine (not that you really notice, plus having extra driving force reduces the effect).

By running diagonal 2WD, you've still got a bit of resistance to veering off because of the offset nature of the wheels, but without the expense of doubling up your motors and/or uprating your speed controller. You lose a bit of manoeuverability, again because of the increased resistance, but as before it's not something you're really aware of.