Starting Point

[RogueTwoRobots]

^ What he said ^

50A per channel will give you a relatively good safety margin as well - the 30A controllers I use with the slightly bigger 40A relays on them have never suffered while being connected to two drill motors each so having 50A each side should see your robot perform comfortably enough in the arena. Add to that the fact it's been designed and constructed with robot combat in mind, it seems like a good unit.

I've never used one before so I don't know how precise it is with its motor control (instantaneous, responsive, etc) but I imagine it will be quite positive. From the reviews of the other Wotty models, Ian has put a lot of effort into these so I reckon it would be a worthwhile investment

[zoll]

Yeah i'm buying it more on his reputation and the experience people have had with his past controllers. Think after that i will just about have all my parts.

One thing i noticed in the wotty100 instruction he sent me was to use a power breaker in the supply line before the wotty100. Whats he refering to here?

Also what size grub screws do i need for locking the gearboxs on drill motors, is it something like 8mm M5's?

[team_orr]

refence the drills: http://www.robowars.org/guides/guides-d ... cking.html

[zoll]

Could anyone recomend me a good cheap battery charger for these http://cgi.ebay.co.uk/7-2v-NiMH-3700...item3357365ba0 Thanks

[psycho_fling]

the one i told you about is still for sale

[zoll]

Ok i have the motors base and most the body made now, unfortunatly no picutres as my camera broke and am now back at university.

Next thing im looking at doing is building an electric axe with a scooter motor, basically have the design figured out what im a little confussed on is the electronics of it. How can i make it only rotate 180 degress and not just continually try to spin?

[elobire]

not sure if anyone has refered you to this but it shows how to make a axe:
http://www.robowars.org/wikka/ElectricAxeWeapons

[zoll]

yeh thats what im going for from a design point of view i just dont get how to limit its range of movement

[elobire]

same thing i was thinking about when reading it. if i find a solution il get back to you

[RogueTwoRobots]

There are a few ways to stop the axe trying to continually spin once it has reached the end of its travel. The first one is quite simply to let go of the transmitter stick you are using to control the axe. You have to keep an eye on your axe travel during a battle and as soon as it gets towards the end of its travel, remove the power to the axe motor by letting go of the stick. I believe this is the method used in the above guide for Avenger. Avenger's axe motor is also controlled by a speed controller, rather than just being on/off control. That means, using a little bit of transmitter limiting, you can set the return speed to about 20% of the total speed so your axe isn't firing full-speed into your chassis when retracting.

The second method would be to install a couple of small microswitches mounted at either end of the axe's travel to act as limit switches. Essentially they are wired up in such a way that, when the axe hits one of these, it removes power from the battery to the motor and stops rotation. But it only stops rotation in that direction, which means you can still reverse your motor/axe and then have it cut battery power again once it has retracted and hit the other limit switch. I can draw up a wiring diagram of that if you wish (been a few years since I tried that method but it's still in my brain somewhere )

Third option, and probably a bit over-the-top for a basic weapon, is to fit a clutch between the transmission and the axe. You can set it so that the torque required to turn/fire the axe doesn't cause the clutch to slip but once it hits an oppponent (or your chassis) and tries to continue spinning, the clutch will slip and give you time to turn off your motor. It goes without saying that this would require the highest degree of engineering of the three methods; personally I wouldn't bother with one (mainly because I don't have the facilities/skills to make one)

So yeah, either method 1 or 2 would work well enough. If you go down the limit switch route, I'd advise maybe putting a bit of foam (or similar) padding over the limit switches; having a rugged axe arm hitting down directly onto the little plastic bodies and metal triggers of the switches will probably annihilate them very quickly. The foam can then also double up as a form of shock-absorption.