I have been in a number of knex battle bot competitions. Each time I learn a few new things about making a winning battle bot. I'll summarize the basics and show you how to make a piece efficient battle bot.
The main thing to remember when you are planning is that you will be supplied with a limited amount of parts. So think basic! The person who tries to be fancy always looses. Many times I've seen cars that don't even have steering come in the top three. The people that win almost always have these five things:
Low center of gravity
Low to the ground
Weight over the wheels
I'll show you how I achieved these things in a battle bot I made that won first place, and I'll give you some tips along the way.
I hope this guide will help future battle bot builders!
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Step 1: Creative Planning
Your planning time can be some of the most valuable time you have, and depending on the contest you might have very little. You do not want to waste it!
Think simple! You will be given a variety of parts and you probably wont want most of them. I know that a lot of times they give you a bad selection of parts to make you think and be creative, but never forget the fundamentals! Don't waste time and parts on fancy spinning things and lifts to flip the opposing car. I made this mistake my first time to compete and I had to spend half of the time I got to battle rebuilding my car. Just don't do it!
Step 2: Low to the Ground
Keep your car low to the ground! If you can use the small wheels for your car. If you keep the car low to the ground your opponent will find it a lot harder to get under you and lift you off the ground.
I know that some of you are thinking that if you use the small wheels you will have less friction between the wheels and the ground. That is true, but there are ways to overcome that. If you only have the big wheels be sure to build the front of the car as close to the ground as you can.
Step 3: Weight Over the Wheels
It's important to keep the weight over the wheels. This will help add more friction between the wheels and the ground and it will be more difficult for your opponent to push you.
Here is a helpful tip. Always use all of the parts you are given! Start by making the basic battle bot then add all of the extra parts over the wheels. Don't build it too high though. You want to keep a low center of gravity. If you build it too high it will be easy to flip your battle bot.
There is almost always those one or two people that have the majority of their parts left. They always loose. You want your bot to be the biggest and most compact one there.
Step 4: Steering
Steering isn't always a must to get in the top three, but the car that wins always has it. It takes a little longer to make, but it will be worth it.
They almost always give you two knex motors for this reason. The way you create steering is by having two different axles that can move independently. Each axle has one motor on it so when you turn both on it either moves forward or backwards and depending of what combination of on and off you use it can steer in any direction.
Step 5: Keep It Flat
You should try to keep the front of your battle bot as flat as you can. This can be hard depending on what parts you are given. But if you keep the front as flat as you can you lower the risk of getting hooked onto your opponents car. Trust me, you don't want that!
You also want to have a wide wheel base. Make it at wide as you can. This will make your car more stable, and will be less likely to get knocked over. You might want to add a stabilizing arm on the back like I did. If you let it drag behind you it will cause a little more friction.
If they give you gears be sure to gear down the wheels, but chances are the wont. I have never been in a competition where they have given you gears.
Step 6: End
I really hope this has helped you with your battle bot. If you have any questions please feel free to ask.
If you ever need help on your battle bot or any other knex project please let me know and I'll be glad to help!