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HOWTO - Parts

This is a basic guide on howto build an antweight and will hopefully turn a pile of parts into a deadly fighting machine.

 

When building an ant there is one main goal, <150g. This may sound easy and is if you have no weapon, however the weapon can add 60g taking the ant overweight. And even if it's 149g on your scales it maybe 152 on battle day, it happens.

 

The next bit will explain the basic components of an ant:

Drive, to drive an ant the most popular was is to use micro servo's and modify them for 360 degree rotation (they normally only rotate 90 degrees). Other methods of drive have included slotcar motors with speed controllers.

 

Modification isn't too hard if you have build model kits and have a steady hand.

 

Modification won't be mentioned here, the principle is the same and two descriptions can be found below:

 

Modifing SD200
http://freespace.virgin.net/oliver.steeples/antweight/antmotor.htm

Modifying HS81
http://www.robotwars101.com/engineering/radiocontrol/additional.html


Batteries, these can take up the majority of the 150g limit if your not careful. There are only two choices until I get corrected, NiCad (Nickel-Cadmium) or NiMh (Nickel-Metal Hydride). NiMh are very slightly more expensive but contain a higher charge rating (Ah, Amp hours, or in out case mAh. milli Amp hours).

 

For an ant without a weapon or low drain weapon 100mAh batteries can be used, typically 4 cells are minimum (4*1.2V=4.8V) although depending on the weight of the ant it can go upto 6 cells, 7.2V. For spinning related weapons 300mAh is really the minimum value you should look at.

For batteries I highly recommend Overlander.co.uk


Receiver, (Rx). Although the ant rules allow IR (infra-red) and other exotic control types, normal remote control is the most available way of controlling an ant. Unlike Robot Wars antweight rules allow 27, 35 (not preferred), 40Mhz and higher. This allows existing RC (Remote Control) equipment to be used reducing the cost of building an ant.

 

Normal Rx's can typically weight 40g, pictured is a Hitec feather receiver weighing approx 10g without crystal (another gram). This lost 30g can allow a weapon to be added.


Mixer, not vital but nice if you have £13 and 5g spare on your ant, the details of a mixer can be found below.

 

Shown is a GWS mixer.

 

As already mentioned modified servo's are normally used to drive an ant. If servo's are being used the type of drive is called 'independant drive' or tank drive, this means both wheels are being driven independantly. As a contrast RC cars have 1 drive motor and a servo controlling the steering, the bad point of this is the turning circle. With independant drive the turning circle is 0, turning on a coin is possible.

 

Now for that mixer explanation.

This is how a basic ant would be driven, the Rx is connected to the drive servos.

 

This means on the transmitter (Tx) you need 2 sticks, one goes forward and back and the other goes forward and back. Not many Tx do this and if it does it normally has a ratchet on one channel so it won't return to 0 when the stick is let go.

 

For a RC car Tx this can be very confusing. You have to either swap one of the sticks round on the Tx so it goes forward-back or you have to learn to drive so left-right goes back-forward.

By including a mixer driving is made easier. The mixer takes the 2 forward-back channels and 'mixes' then into a forward-back and left-right channel.

 

So on the Tx when you press forward on the stick the ant goes forward and the same with reverse.

 

When you go left the clever bit kicks in as one motor goes clockwise and the other goes anti-clockwise so the ants spins on the spot.

 

This is very good if you have a RC car remote as it will control an ant without modification or confusion.

 

The only bad point about mixers is if you push forward 100% and turn it won't turn as you expect due to the way the mixer handles the inputs. You have to decrease the 'throttle' to say 80% and turn, this will allow the ant to turn as you want.

 

Now, an idea

 
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