Introduction: Combat Robotics Tutorial

***DISCLAIMER: Some of this information could be better or is inaccurate.  Specifically how big of a battery you need.  I plan on making a new tutorial eventually, but for the most part this tutorial is accurate.***

Have you ever wanted to build a combat robot (battlebot), but gave up because you didn’t know where to start? Well, hopefully this tutorial/instructable will help. I condensed a lot of information down into a step by step process, taking out most of the stuff you really don’t need to know, but leaving the crucial information. This tutorial is focused on the insect weight robots (75grams to 6 pounds), because the majority of competitions held are for insect weight robots, and they are the least expensive.

Throughout this tutorial I will be putting a robot together for demonstration. I used wood for a material,and you shouldn't.  The reason why I used wood, was because I was just putting the robot together for this tutorial, and I am never going to compete with it.  In fact I already threw it away, because it was a mix-match of a bunch of different ways to do things.

Step 1: Weight Classes

Before you do anything else, you have to pick a weight class. The weight constraint helps determine which parts are needed.

Insect Weight class:
• 75g Fleaweight (not common)
• 150g Fairyweight (5.3oz)
• 1lb Antweight
• 1kg Kilobot (Canada Only)
• 3lb Beetleweight
• 6lb Mantisweight (not common)

I suggest building an antweight or a beetleweight as a first robot, because you don’t have to be as concerned about weight as with lighter robots. It is less expensive to build a antweight, but you will find it easier to stay under the 3 pound limit. Also, beetleweights are more common than antweights, but any competition that has beetleweights will have antweights, and vice-versa. So, it is really up to you, just pick a weight class and go with it, you can always build another robot for a different weight class.

Step 2: Weapons

The different types of weapons seem to be endless. There are two main categories: active weapons and passive weapons. Active weapons are any weapon that moves. Passive weapons basically turn the whole robot into a weapon, via a wedge, spear, or something of that sort. I have a bias towards active weapons, because the matches are more action packed, but robots with passive weapons are very successful due to their inherent strength.

Passive Weapons:

Wedge Robots:
  These robots use a wedge to flip the opponent over. They usually have very strong drive motors. To defend against wedges, make sure your robot can flip itself back over, or can drive upside down.

Spear Robots:
  These robots use a spear to pierce the opponent’s armor. They require very strong drive motors, and sometimes even that isn’t enough power to get through the armor. Spear robots are very uncommon in insect weight robots, because it is difficult to find motors powerful enough to make the robot able to pierce armor. To defend against spear robots, make sure you have strong armor.

Active Weapons:

Horizontal Spinners:
  These robots usually have a fast spinning and heavy bar that does a lot of damage. They also put a lot of strain on their own parts though. The best defense against these robots is to have strong armor and all of you electronics shock mounted (Velcro). This area of weapons includes but isn’t limited to:
• Horizontal Bar Spinners
• Full Body Spinners
• Undercutters

Vertical Spinners:
  The robots usually intend to flip the opponent over, and do damage with weapons that have “teeth” on them. The best defense against these is to either have armor that won’t get chipped apart, or will let little pieces come off at a time, not all at once. This area of weapons includes but isn’t limited to:
• Saws
• Drums
• Vertical Bar Spinners

  Most of these robots use pneumatic cylinders to quickly move a flipper or hammer. Most of the time hammers aren’t very effective on insect weight robot, because it is hard to make one with enough force to pierce armor, and keep it under the weight limit. The best defense against a hammer is having durable armor. Flipping robots are effective against robots that can’t drive upside down. But with the exposed arms that are used for flipping, they aren’t very durable. The best defense against a flipping robot is being invertible. This area of weapons includes but isn’t limited to:
  • Hammers
  • Flippers
  • Motorized wedges

Rare Weapons

   • Fire breathing
      These robots usually aren’t very effective, unless their opponent has some parts made of wood. Also some events don’t allow fire breathing robots. The best defense against these robots is to make sure no electronics are exposed, but you will probably never face one of these robots in the insect weights.

    • Multibots
       These robots are more than one robot working as one. An example would be three 1 pound robots competing as a beetleweight robot. These robots are slightly more common than fire breathing robots.

No weapon is the best, if it is built strong; it is just as effective as any other weapon. Some weapons such as a full body spinner may seem unbeatable, but when the robot has to spin something that heavy that fast, it puts a lot of strain on all the components, causing things to break. Also certain weapons work better against certain types of robots.

To conclude for the best defenses: make sure your robot is invertible, has strong armor, no electronics exposed, and all the electronics are shock mounted.

One thing I learned with my first robot, Titan, is that you should use a bigger shaft size than you think. For example, on Titan I used 1/8” diameter shaft for the drum, but it snapped in 4 out of the 6 matches I had. That being said, generally these sizes will work:

-Fairyweight – 1/8”
-Antweight – at least 1/4”
-Beetleweight – at least 1/4", but 3/8” would be better.

Step 3: Design

This is step is just tips, because everyone designs in a different way.

Tip 1:
When designing a robot one important thing to keep in mind is weight.  I usually start to pick out parts, and make a chart with the weight. 

Tip 2:
Draw it in a CAD program.  This is probably on of the most important tips I can give.  Not only does it help you end up with a better robot, but it can save you money too.  When you draw it in a CAD program you can try out designs and different parts without ever buying any parts.  I usually go through 10-25 different designs until I get to the prototyping stage.  Then I refine it once or twice, and the robot is just the way I want it.

Tip 3:
Leave extra space.  Although all if you draw it out it may look like all the electronics will fit in one tiny area.  But, when it actually comes to putting it together it doesn't fit right.  Most of the time it is because there isn't enough room for all the wiring.  I am currently running into this problem with my antweight.

Tip 4:
Tell someone about it.  If you have a friend that is interested in this kind of stuff, talk to them about your design.  They might point out some key things that you overlooked.  I have found that working on a robot with someone else yields a much better end result. 

Tip 5:
Don't jump right into building the robot after you have designed it, unless you have a very short amount of time.  If you just think about the design for a few days you will usually come up with some improvements.  I usually draw about 5 times on paper (not to scale), changing a little every time, and then I draw it it Rhino (CAD program).

Step 4: Basic Parts

The basic parts that you need are:

• Drive Motors
• Wheels and Hubs
• Drive Speed Controller
• RC Radio / Receiver
• Batteries
• Power Switch / Link
• Weapon Motor (If Design Requires)
• Weapon Speed Controller(If Design Requires)
• Wire
• Connectors

All of these parts can be found at:

Suggested Parts:

Drive Motors:
• Fairy – 100:1 SRV Drive Motor (or similar)
• Ant – 100:1 SRV Drive Motor (or similar) or FingerTech Spark Series
• Beetle – FingerTech Spark Series or B Series Motor

FingerTech Silver Spark motors are great  motors and have plenty of power for an antweight.  Some builders use them in beeteweights with success too.

Wheels / Hubs:
• Fairy – Lite Flite Series Wheels w FingerTech Hub
• Ant – Lite Flite Series Wheels w/ FingerTech Hub
• Beetle – Lite Flite Series Wheels w/ FingerTech Hub or BaneBots Wheels/Hubs

Drive Speed Controller:
• Fairy – FingerTech tinyESCs
• Ant – FingerTech tinyESCs
• Beetle – FingerTech tinyESCs or BaneBots 3-9

When choosing you speed controller, choose your drive motor first, and then match it up with a speed controller that can handle the amps of the motor.

RC Radio/Receiver:

For combat robots the radio/receiver HAVE to have failsafes on all channels.  That means that if signal is lost, or the radio is turned off, then channels will turn off, and the throttle channel returns to its set position.

I suggest the Spektrum DX5e radio paired with the Spektrum AR500 Receiver, or if you need a lighter receiver go with the Spektrum AR6110e. I suggest these, because they have failsafes built in, making them legal for use in combat robotics. Also the DX5e and AR500 combo package is only $100. That gets you a radio and receiver with the best technology on the market. They have great range and virtually no interference. Also since it is 2.4GHz all you have to do is bind it once (very easy to do), and then you don’t have to deal with frequency crystals. Most of the 72MHz (radios that use frequency crystals) radios and receivers are more expensive than this too, making it almost a no-brainer. But, there is a GWS brand system available for around $80. Sure, you can go for the GWS system and save $20, but it won’t have as good of range, you will have to carry different frequency crystals for competition, and it won’t last as long. As far as I’m concerned the only way to go is the DX5e paired with either the AR500 or the AR6110e.

EDIT: spozman has brought this radio: HK-T6A and this receiver: HK-TR6A to my attention.  They are sold by FingerTech and are legal for use in combat robotics.  They are also 2.4Ghz, but almost half the price as the DX5e and the AR500.  I can't vouch for how well they work, but they appear to be perfectly fine for a robot.  If you are on a budget, definitely go for this radio and receiver, but if you don't mind spending a bit more, then go for the DX5e and the AR500. 

For insect weight robots Lithium Polymer (LiPo) batteries are the most common. The reason is because they are so light. They may be a little pricey, but if you take good care of them they can last 5 – 20 years (depending on how and where they are stored). I won’t go in to all the details about charging and care for LiPo batteries, because there are many websites that can explain this better than me (just type “safely charging discharging and storing LiPo batteries” into a search engine). But I will say this: Don’t short them out, because they will swell, catch fire, or explode (none of which have ever happened to me). But don’t let that discourage you from using them, because if you just use some common sense the batteries will be fine.

When deciding how many Amp Hour you need for batteries add up the stall current of all of your motors, then divide the the Amp Hour value of the batteries by the total stall current.  If you multiply that number by 60 you will get how long the batteries will last in the worst case scenario (stalled motors) in minutes.  The batteries should be able to last at least 3 minutes.

*EDIT*: The above advice about battery size is bad advice. You will end up with a battery size that is much bigger than necessary. 

Power Switch:
• Fairy – Removable Link
• Ant – Removable Link
• Beetle – Wyachi MS05 or Removable Link (If you need to save weight)

Removable Link
• A very simple power switch that can be made by follow the steps in this video:

Wyachi MS05
• A bit expensive, but very effective switch. It takes 4 turns with and allen wrench to turn it on and off, making it unlikely to fail during combat. I suggest it over a removable link, because it is much more durable, and there is less of a chance of it shutting itself off during combat.

Weapon Motor:
I highly recommend brushless motors. I don’t have a specific motor to suggest, because almost all brushless motors are well built, and they come in so many different sizes that only you know what size you want for your robot. If I had to suggest a brand it would be E-Flite. The reason why brushless motors are better is because they don’t draw as many amps, they are much faster, and they don’t get nearly as hot. I had a brushed motor get so hot that it started to melt the plastic mount.

Weapon Speed Controller:
Once you pick a motor, most of the time there will be a recommended speed controller on the motor’s page. If there is not, you can look through the speed controllers on Robot Market Place if you know what specs you need, or you can leave a comment asking which speed controller to use, and I will be more than happy to answer it (usually within a day or less).

When choosing wire go for Silicone wire of Deans Ultra Wire, because they are the most flexible, and can handle the most current for their gauge size. The wire is a little bit more expensive, but well worth it.
As a general rule for wire gauges:
- Beetleweight – 14 to 16 gauge
- Antweight – 16 to 20 gauge
- Fairy - >22 gauge

It’s good to use connectors for attaching electronics together, that way it is easier to swap parts if they break. I like Deans plugs, but any of these connectors will work (as long as they aren’t way to big): Connectors

Step 5: Materials

One major question is: What material should I use?  There are a lot of different materials that will work, you just have to decide what properties you must have (i.e. strength, weight), and what properties don't matter to you.


Material Family - Plastic/Metal
Impact Strength - How much of an impact the material can handle.
Tensile Strength - How well the material can handle being pulled.
Flexibility - How flexible the material is. (Relative i.e. grabs material, twists it, yes it flexes)
Density - Density from Machinist -Materials
Main use - Armor/Base-Plate/Etc.

Here is a list of commonly used materials:

UHMW (Ultra High Molecular Weight)

Material Family - Plastic
Impact Strength - High
Tensile Strength - Low-Medium
Flexibility - Medium-High (I wouldn't make a base-plate out of it)
Density - .034 lbs/in3
Main Use - Armor

This is a great material.  I use it for armor on all of my robots.  I wouldn't worry about the low tensile strength, because with its high impact strength and low weight it is the perfect armor for insect-weight robots.  Also, this material is very affordable.


Material Family - Plastic
Impact Strength - Medium-High
Tensile Strength - High
Flexibility - Rigid
Density - .051 lbs/in3
Main Use - Baseplate/Armor

I am using this for a baseplate in my current robot, Slash.  It is very rigid, and is still fairly light.  Also it is affordable.


Material Family - Plastic
Impact Strength - High
Tensile Strength - High
Flexibility - Rigid
Density - .043 lbs/in3
Main Use - Baseplate/Armor

This is a good material for armor, but has a tendency to crack after big impacts.  Also it is quite a bit more expensive than Delrin and UHMW.


Material Family - Metal
Impact Strength - High
Tensile Strength - High
Flexibility - Rigid
Density - .101 lbs/in3
Main Use - Baseplate/Armor

I don't suggest using aluminum, because once it bends, it doesn't bend back.  The Base-Plate of Titan is proof of that.

Carbon Fiber

Material Family - Composite
Impact Strength - High
Tensile Strength - High
Flexibility - Rigid
Density - .0643 lbs/in3
Main Use - Baseplate/Armor

Don't use carbon fiber, or any composite for that matter.  Carbon fiber has great properties, until it breaks.  When a normal material breaks, usually just a little piece breaks off, but not for carbon fiber.  Since carbon fiber is made of woven strips of carbon fiber fabric, when it breaks it ones spot it starts to break all the way through.  In other words, with composites it's all or nothing.  They sound like the best thing ever, but with one little break all those awesome properties go away.

*EDIT: I have since changed my mind a little about carbon fiber.  It will work in lower weight classes (<1lb, 3lb is pushing it), but don't be surprised if it breaks after a big impact.  Personally I would sooner go for delrin, because it is just as rigid, and will stay together better in big impacts.  Also delrin is surprisingly lighter.  


Material Family - Metal
Impact Strength - High
Tensile Strength - High
Flexibility - Rigid
Density - .16 lbs/in3
Main Use - Baseplate/Armor

Titanium is the perfect blend of strength and weight.  It does weigh more that twice what UHMW and Delrin weight, but it is worth it on some pieces.  Most of the time Titanium wouldn't be used for armor unless the robot is a wedge robot.  It is very useful for use in a weapon though.  It is what I am using on Slash.


I picked these materials because they are the most commonly used in insect-weight robots.  I left out some materials like steel, because they are rarely used, and when they are it is for the weapon.  If a material isn't listed here that doesn't mean that you shouldn't use it on a combat robot, it is probably just a material I forgot to mention or didn't know about.

Step 6: Motor Mounts

The easiest to make, and the best motor mounts in my opinion are clamp style. Basically it is a square block with a hole for the motor, and a notch to allow tightening.

This video gives the step by step process of making one:

Step 7: Base Plate

Most of the time insect weight robots don’t have a chassis, instead the armor is attached together, and the components are attached to the armor. You could consider the base plate to be the chassis, but it is also armor. Things to keep in mind when designing:

Placement of electronics-
  Make sure to have plenty of room, otherwise it will be difficult to repair between matches, and things are more likely to break if they are packed together.

Wheel Placement-
  Combat robots use “tank style” driving. This means that there are 2 to 4 wheels, and both sides operate independently allowing for a agile robot with a short turning radius. Also you have to protect your wheels, because they are the first target during a match. Exposed wheels are easy targets for a robot.

This video shows the step by step process of making a base plate:

Step 8: Armor Attachment

These are good way to attach armor pieces to each other and the base plate:
• “Angle-Iron” (available in plastic)
   -Works when the armor needs to be attached at a 90 degree angle. Screws or glue can be used to hold it in place.
• Glue
   -Just gluing everything together can work in insect weight classes. I don’t recommend using glue, because it isn’t very strong, and good robots will tear the armor off in seconds if it is held on only be glue.
• Hinges
   -Hinges are popular in attaching wedges to a robot, because it allows them to sit as close to the ground as possible.
• Milling entire robot out of one block of material
   -This way there are no joints; the problem with this is when part of it breaks the whole thing has to be replaced instead of one piece of armor. But this solves the problem of entire pieces of armor being torn off. This is usually very expensive, because it requires a lot of milling.


Step 9: Mounting and Powering a Weapon

The best way to mount a spinning weapon is to use bearings that are inside bearing blocks to support the shaft. I have found it difficult to find places to buy bearing blocks from. So, you will need to find bearings that will work for you shaft, and then make your own bearing blocks. It is difficult to make bearing blocks by hand, so it is best if you have them machined. The blocks should attach to the base plate by screws of bolts, providing a sturdy support for the weapon shaft.

A pulley should be attached to the shaft to power the weapon, because if the weapon is attached directly to the weapon motor, the shaft of the motor is likely to break. Replacing a weapon shaft is much cheaper than replacing a motor.

This video provides a step by step process of mounting a weapon:

Step 10: Mounting Electronics

For insect weight robots Velcro works the best for mounting electronics. This is suggested in the RioBotz tutorial, because it absorbs shock, and it makes it easy to remove the electronics. Some Velcro is very “flat”, and doesn’t move around much, this Velco won't work as well.

Duct tape will also work in little loops. But it needs to be switched every few matches, otherwise it will come loose.

Step 11: Wiring Your Robot

Haven’t given up on your robot yet? Congratulations, because it will soon be up and running and you will have that satisfaction of driving it and knowing that you finished. It’s hard to explain in writing how to wire the whole robot, so for some of the parts that apply in general I will explain it in words, but the video will include everything.

Here are the videos:

Part 1:

Part 2:

Part 3:

The receiver uses a 3 prong connector, one for positive (5v), on for ground, and one for data. The Sabertooth 5RC has cables that come off of it that will plug into the receiver. Make sure that the red wire matches up with the pins on the receiver that are label with a “+”. Most of the time the cable labeled “drive” should be plugged into the “ELEV” slot on the receiver. Also the cable labeled “turn” should be plugged into the slot labeled “AILE”. If you have a weapon, then that speed controller should be plugged into the “THRO” slot, so that you can control it with the throttle stick that stays in place on the radio.
If you have a weapon and a Sabertooth or RoboClaw speed controller, then the red wire MUST be removed from the plug on the weapon speed controller. The video contains instructions on how to do this. If you don’t remove the red wire, both the weapon speed controller and the drive speed controller will try to supply the receiver with 5 volts. This function on the speed controllers is called a BEC, or Battery Elimination Circuit, because there is no need for having another battery to power the receiver. The result if you don’t pull out the red wire is that one, or both, of the speed controllers with be fried (it has happened to me).
On most speed controllers there is a screw terminal label B+ and B-. The power wire should be put in the slot labeled B+, and the negative power wire should be put in the B- slot. For the motors, the wires don’t have to match with the labeling, as long as both wires on motor 1 go to motor 1+ and 1– on the speed controller, and vice versa for motor 2. The reason why “+ and –“ don’t matter, is because if it is backwards, the motor will just go in reverse instead of forwards when you try to drive forward. So, you have to try different arrangements until the motors behave correctly. For help on troubleshooting this, look at the video. The video also contains how to configure the DIP switch (the thing with a bunch of switches on it).

There is a great video on binding the DX5e on Robot Market Place: Here

Step 12: Adding Weight

An easy way to add weight to get your robot closer to the weight limit is washers. They can be bolted on to the armor, making them easily removable. If you have a spinning weapon that is causing the robot to shake a lot, placing the weight by the weapon will help the robot not shake as much.

Step 13: Losing Weight

One way to lose weight is replacing the armor with armor that weighs less. This will work if you need to lose a lot of weight. But if you need to lose just a little weight, you can drill holes in the base plate. Another alternative is to get lighter parts.

Step 14: Rules

Most events use the RFL Tech Regs. These rules have parts that can be changed, meaning most events will be close to the same rules, but not the exact same rules. Such as the part that allows or doesn’t allow fire. Make sure to check the rules of the competition you are going to before registering.

Some things to make sure you have:

-Safety Pin
It must be capable of stopping your weapon. Usually it sticks through the weapon or is in a position that the weapon will hit and stop.  It is also supposed to be painted a bright color

You are supposed to put something under your robot at competition to prevent it from driving off by accident.

-Power Light
At competition you will need a light that comes on when your robot is powered on. How to make a power light is covered in the wiring section.

Step 15: Tips

1. Don’t Give Up!!!
  At times building a combat robot can be extremely frustrating, but if you just stick with it, you will be able to finish. Also when you are finished you can brag to all your friends about how awesome robot..

2. Draw it out
  I highly suggest getting drafting software for your computer. If you are a student, you can get Rhino for <$200. Trust me, it is worth every penny. It isn’t just useful for this project, but for just about any project. If you have it drawn out, it will be much easier to build.

3. Mock it up
  Make sure to mock up your robot with cardboard or wood before spending money on more expensive materials, just to realize that your design wasn’t quite what you wanted. One thing that I learned from building my beetleweight, Titan, is that you should draw every part out and mock every part up. The reason I say this is because the problems I ran into were with the parts that I didn’t draw out and mock up, I just had their design in my head, big mistake. I would have saved me a bunch of time to just draw it out and mock it up to work out all of the kinks first, instead of trying to make it work on the final design.

4. Don’t be afraid to ask questions
Leave your question as a comment on this instructable, or PM me if you don’t want others to know your plans. I will be more than happy to answer your question, and I will usually answer within a day.

5. Have Spares!
  You might think that your robot won’t break, but trust me, something will break. Often it is something you never thought of until it is broke and your robot can’t function without it. So before you pack up your stuff and travel halfway across the country make/buy some spares.
For my first competition I travelled 8 hours, and if I hadn’t decided to make some spare shafts with the leftover rod I had, I would have ran out of shafts. In fact, I had 4 shafts, and in my last match the fourth shaft broke. It may seem like a waste to buy a bunch of spare electronic, but you can always use them on another robot. It is also a good idea if you have more than one robot to try to make them share parts, so you have to carry as many spares.

6. Buy a Scale
  Accurate postal scales (<5lbs) are available for <$30. It will be very helpful in staying under the weight limit.

7. Practice Driving
  In Dave Calkins’ (founder of RoboGames) Guide to Winning, he stresses how important it is to practice driving. I couldn’t agree more. After I finished my robot, I laid out a track with a lot of sharp twists and turns and started driving. At first I couldn’t stay within the lines at all, but after about 2 hours I was able to zip through the course. I wish that I would have practiced more on a moving target, because I still had a little trouble driving at the competition. You have to remember, your competitor is trying to get in the perfect position to strike also, so you have to be able to quickly maneuver to attack, and prevent form being attacked.

8. Registration
  To register for an event go to Builders Database.

9. Take pictures and videos at the competition
  Be sure to get video of all your matches. It will be very helpful when redesigning, because you can go back and see exactly what happened. When I went to Mecha-Mayhem 2010, the one thing I wish I would have done more of is take pictures. Now that I look at all the matches on video, I wish that I had pictures of the damage to my robot (I repaired it between matches so the damage isn’t still there, except from the last match).

Step 16: Final Thoughts

I have learned a lot of what I know about combat robotics from the RioBotz Tutorial.  So, a big thanks to the people of RioBotz.  I highly recommend checking it out, because whenever I have a question about combat robots I grab the copy of the RioBotz Tutorial I printed out and look it up. 

Many people think that combat robots is a dying sport.  I don't think that it is true, because there is a lot of competitions in the US, and even a few in other countries.  It may not be focused on the heavyweight robots like it used to be, but insect weight robots are very popular.  In fact there are 10 plus events in the US for insect weight robots.

You can look at my robotics website here: Titan Tech Robotics


Zaphod+Beetlebrox made it!(author)2016-03-17

Does anyone run micro-controlled insect weights. Would an arduino or pi stand up to the abuse. Or is there another reason why they are all directly RC controlled?

NickH123 made it!(author)2016-08-07

It's not exactly Arduino, but there's an Atmel based dual channel programmable ESC that I plan to use on my Beetle weight bot. It'll control 2 sets of brushed motors for tank style steering.

It's not just an ESC, they provide the source code for the ESC, and allow you to program it and use the remaining I/O pins for sensors, etc. What's exciting to me is that this costs about $20, and replaces $60 worth of ESC, while adding autonomous capabilities.

Zaphod+Beetlebrox made it!(author)2016-08-09

Oh cool thanks I look into it.

JaredsProjects made it!(author)2016-03-18

Not that I've seen. RC is common because it is easy to set up and a human controlling the robot is typically going to be better than an autonomous system. However, arduino and raspberry pi should be able to handle the same abuse.

Zaphod+Beetlebrox made it!(author)2016-03-19

Ah, okay. I am thinking if using a Bluetooth controler on the arduino. Just seams like nobody does this and I was wondering why. But I guess RC is easier.

VardaanB made it!(author)2016-01-26

I was wondering, there are multiple gear ratios of the motors, does which one I get matter? Will the gear ratio affect the size of the wheel as well? Sorry, I'm quite new to this.

R1885 made it!(author)2016-01-28

Yes. The higher the gear ratio, the slower the motor will spin, but it will improve acceleration and reduce stress on the motor. Don't go gear to high, though. Too high and the speed of the robot will be a crawl.

Wheel size effects the gearbox, not the other way around. A larger wheel requires more toque to spin(ie; will cause the motor to eat more amps), but will also improve top speed. Beware, if the wheel is too big, the motor WILL fry itself just trying to spin it. Smaller wheels require a lot less effort to turn, but will result in lower overall speed.

What kind of speed and acceleration you'll need will depend on what the bot is doing, the weight of the bot, and the size of the arena. My rule of thumb is to be at max speed by the time you've reached the middle of the arena, any speed you'll have will be more than enough to work with. My current antweight(1lb) runs a pair of 11:1 Fingertech spark motors at 7.4 volts(Unloaded speed of 1049rpm) with 1.5" wheels, and the speed and acceleration are spot on for my needs. You may need to bump up the gear ratio or change the wheel size to get a speed you will like.

PrasannaK12 made it!(author)2015-10-26

hi,i am an student.i am taking part in an manual robot fighting competition but i don't have any idea about what type of robot to build and the rule of competition is_1. U cannot damage other's cannot exceed the weight of robot more than 3 kg and size more than 30 cm l*b*h_3.u cannot use any weapon except a wedge_4.u cannot damage the game arena .what should i do.plz help me.thank u

MaxP22 made it!(author)2015-10-04

How do you connect the sprocket to your motor?

BerlinW made it!(author)2015-08-04

Nice blog thanks for sharing useful information. For more robotics tutorials and learning visit

The_Angelic made it!(author)2015-08-03

Thank you! This was major help! I was just having problems coming up with a good design, and this helped a lot!

AkhilM4 made it!(author)2015-06-16

Hello, me and my friends are entering in the antweight category for RoboGames 2016. Would this micrometal gearmotor be good for the drivetrain?]

Also, would a 460mah 3s turnigy nanotech be able to run two of those motors and one of these: for my weapon well?

Thanks in advance!

R1885 made it!(author)2015-06-30

Dude, those motors have like no speed. If want decent motors for a weapon baring ant(which you failed to state what kind of weapon it is too), you might want to try these motors:

AkhilM4 made it!(author)2015-06-16

I switched it to 2s, but similir mah

bccase16 made it!(author)2014-03-16

what did you make your drum out of? what would be a good weight for a drum in the beetleweight class?

shadow81200 made it!(author)2015-06-24

If you don't have a lot of tools you could take some steel or iron pipe and drill holes into it. Then after drilling the holes feed a bolt through them and thread on a nut. Last cut off any excess threads off the bolt that stick out past the nut. You don't need a welder so that is helpful. This design will let the head of the bolt and the nut catch onto other robots.

utkarsh.rawat.1253 made it!(author)2015-01-17

which SPEED CONTROLLER....should be used for beetle&ant size combat robot

R1885 made it!(author)2015-01-22

Fingertech tinyESC man.

shadow81200 made it!(author)2014-11-09

what would you say are the average dimensions of a beetle weight robot?

Fragmaster made it!(author)2014-03-03

Hi Jared

Can you suggest an ESC for this weapon motor?

Since the motor will be driving a weapon with far too much angular momentum, I need it to be able to coast to a stop. The 30A ESC that I already bought occasionally makes weird sounds and stops responding if I let go of the stick and let it spin down. It works fine if I program it to enable braking, but that just won't be feasible when I attach the weapon to it. Here's the ESC that I bought:

JaredsProjects made it!(author)2014-03-03

The ESC you have should work when braking is disabled. It's hard to tell exactly what the problem is without being able to see it. If you could post a video to youtube and then send me the link I'd be able to help you more.

Fragmaster made it!(author)2014-03-03

I can't post a video until this weekend since I don't have it with me at the moment. Maybe it's just a defective ESC. I bought another one at the same time, which burnt up. So perhaps they are just especially poor quality.

Here's an animation of what the final product is going to look like. (SolidWorks is awesome)

kooljo made it!(author)2013-07-03

hi I am just a beginner. i am wondering what type of battle bot i should start out with. thank you

JaredsProjects made it!(author)2013-07-04

I recommend building a wedge as your first robot because they are easier to build. I now well antweight kits that are great for beginners if you are interested in those. They are available at

kooljo made it!(author)2013-08-05

thank you im more interested in building my battlebot from scrach instead of a kit but i will check kits out to. thanks again

JaredsProjects made it!(author)2013-08-05

I can understand that, building from scratch is very rewarding. If you build your first robot from scratch I recommend mainly focus on just getting it to function. It may not do great at a competition, but just taking a functional robot to a competition is a great place to start. You'll learn a lot in the building process and at the event that you can use on a second version. My first robot (the one in the main picture) was actually kind of terrible. I did a lot of things wrong, but just by taking it to a competition I learned a ton. Even though it wasn't a good robot it somehow managed to get 3rd place, which is ridiculous. There were a lot of other robots at the competition that were better so I just got really lucky.

gokulsmail4u made it!(author)2013-07-10

i am a beginner and want to make a combat robot i like one in the range of 2-10 pounds .Can you give me some suggestions on what type of robot to make

JaredsProjects made it!(author)2013-07-11

The best kind of robot to build as your first robot is a wedge, because you don't have to deal with the complications of a weapon. Usually 1lb robots are the easiest to build as your first robot. 3lb robots are also fairly easy because you have more weight to work with.

yvesyuzo made it!(author)2013-03-12

Do you recommend another motor for fairyweight? a faster one with a shaft large enough to fit finger tech wheels (0.5in or 0.75 inches of Width)

Thank you

JaredsProjects made it!(author)2013-03-12

Are you building a featherweight (30lb) or fairyweight (150g) robot? For a fairyweight I recommend the new mini sparks that fingertech will be releasing soon. There will likely be several gear ratios to pick from that will determine the speed. The shafts on these motors will likely be 3mm (~1/8") as that is what the size of hubs wheels fingertech makes.

If your original question about motor mounts was about fairyweights rather than featherweights, then absolutely you can use UHMW as a motor mount material. That would likely be my material of choice of a fairyweight motor mount because it is strong enough and very light. In my last reply I said I didn't have much experience with featherweights. However, I am much more experienced with fairyweights as I have built one and I am familiar with the components because they are sold on the websites I frequently by things from for my antweights (1lb).

If this is your first robot I recommend building a fairyweight or an antweight because they are much less expensive and are easier to build than a featherweight.

yvesyuzo made it!(author)2013-03-13

Im building both!
But Im focus on the fairy now.
I dont have time and I need a fairyweight motor to fit FT wheels.
The 100:1 RMP is to slow and the 30:1 is to short on the shaft, even the lectra wheels wont fit.
Do you think 5mm armor wall's will be fine on combat?
Thank you for the help!

JaredsProjects made it!(author)2013-03-13

The 30:1 should be fine for the lectra and lite flite wheels if you use a lite flite hub that fingertech sells. The shaft doesn't have to go very far into those because the set screw part is about 1/4" deep. I used some 30:1s with lite flite hubs and they worked fine in my fairyweight.

Depending on the material 5mm should be plenty. My current antweight uses 3mm UHMW in some places. I'm not expecting the 3mm to hold against most weapons though but it should be thick enough to protect the electronics even if the UHMW gets torn up during a hit.

yvesyuzo made it!(author)2013-03-13

I dindn't knew about that, I though the lite flite hub couldn't support the wheels.
Do you know any material besides titanium, to use on a vertical spiner weapon?

JaredsProjects made it!(author)2013-03-14

For a 150g 1/8 Ti should be fine. For higher weight classes I recommend heat treated S7. It will hold up well to almost anything.

yvesyuzo made it!(author)2013-03-07

Thanks for the answer!!
I have another question, about speed controlers and motors.
If for instance i have a Victor 884 with the Maximum Current of 40A continuous, and use it to control the CIM Motor(12V DC), with a Stall Current of 133A. In the case of conecting a LiPo battery(12v) to control the motor the Esc's will burn? No way I could use this combination?
Btw do you have a active robot for this year??
Thank you

JaredsProjects made it!(author)2013-03-07

Victor 884's should be able to control a the CIM motor you're talking about, I put the numbers from the motor into this calculator,, and it shouldn't get close to stalling. Most of the time motors won't reach their stall current because the wheels will start to spin before then. I only build insect weight robots, so I don't have much experience with what motors people are using for featherweights. People from the RFL Forum or the Facebook group called Robotics Community are more knowledgeable in the higher weight classes than I am. You might want to ask around on those forums to see what parts they use. I do have an active robot. It is an antweight called Guildenstern and I plan to compete with it at the Central Illinois Bot Brawl in April ( It's been about a year and a half since my last competition and I've been working on the robot on and off since then. If you have any other questions please ask, I'll do my best to answer them.

yvesyuzo made it!(author)2013-03-03

Do you think UHMW motor mounts should work fine on Featherweight?

JaredsProjects made it!(author)2013-03-03

UHMW probably wouldn't be the best material in a featherweight. I recommend aluminum because if you face mount the motor (screw through the mount into the front of the motor) UHMW wouldn't hold up too well if one of the wheels gets hit. Also, if you use a clamp style mount with UHMW in a featherweight the torque the drive motors in that class generate could make the motors spin inside the mounts because UHMW is kind of a slippery material.

ahleagle made it!(author)2012-12-28

hello im trying to make a beetle weight bot and I'm trying to figure out what battery to get. the motors im planning on using are the "FingerTech spark 20:1 Gear motor" and im looking at this battery it is a E-Flite 1800mAh 2S 7.4V 20C LiPo Battery, 13AWG EC3. i am also using the smallest sabertooth esc the one rated for 5amp continuous and 10amp max per channel. I would greatly appreciate any feed back you can give on the battery subject. Is it a good one? will it work? and why are there two leads comming off of the battery?
the links to the above mentioned items are below. thank you for any help you can give in advance.





JaredsProjects made it!(author)2013-01-01

For the drive motors I recommend that you don't use the gold version of the sparks. They are not intended for combat. Silver spark are much more suitable for combat and are made by the same company. You should be able to find them from robot marketplace. I have never used silver sparks in a beetleweight but I know of other builders who have and they have had success with them. You will probably have to run the motors at 4S (14.8V) for them to work effectively in a beetleweight though. If you don't plan on having a weapon the silver sparks won't be powerful enough for a wedge robot.

For the ESC I recommend fingertech tinyescs. They are the same price (or pretty close) as the sabertooth and are tremendously better. I have used the sabertooth escs before and had a lot of issues with them. If you get the tinyescs you have to buy two, one for each motor.

The battery had two leads because it is Lithium Polymer (LiPo). One lead has the positive and negative (red and black) wires which connect into you robot, these are like the normal terminals on a battery. The other lead has the wires which connect to each individual cell of the battery. This lead is used when charging the battery, because the cells need to be kept within .1V of each other to avoid damage to the battery. LiPo battery chargers take care of keeping the cells within .1V of each other when charging.

That battery is likely too low of voltage if you use silver sparks, and too high of a capacity. I don't know what capacity you need for sure with out knowing weapon specs, drive motor, and tire size. But, 1800mAh is a little overkill unless the weapon draws a tremendous amount.

This will help with motors and battery choice, at least for drive anyway.
Silver Sparks aren't an option so you will have to input their specs from fingertech's website.

ahleagle made it!(author)2013-01-01

What gear ration would you recommend for a Beetleweight in the finger tech spark series silver motors?

black+hole made it!(author)2012-02-02

Perhaps a good defence against saws might be multiple thin plates that could get torn off without doing major damage to the robot. It also might work against spear bots.(The top layer cracks, then the next... giving you more time)

foodcity1234 made it!(author)2011-09-11

what about carbon nano-fibers? they are very strong and durable. stronger than diamond, actually.

mettaurlover made it!(author)2011-09-24

And they can't be produced in useful quantities yet, or for a reasonable cost.

foodcity1234 made it!(author)2011-09-11

i have an idea. how about using a mag lev to hold up the upper half? neodymium magnets work best for mag levs.

cmcmillan made it!(author)2011-07-25

how would i make a flametrower i mean i know how like all i need is some wd40 and like a candle but i dont know how tospray the wd40 from a good distancent

35Timmy made it!(author)2011-09-08

please i just advise that you keep the wd40 away from flames even read it on the safety label if you really want more info in fact it is a hexagon danger of flammablity and same with pioson

minglewithmetal made it!(author)2011-08-18

If you watch the UK robot wars, you see that Seargeant Bash has a massive nozzle and underneath it, there is a tiny little flame. Gas goes through the metal tube,and through the metal nozzle, so the flame 'throws' itself. You might find it a bit hard, but that's all my knowlege. Good luck!

JaredsProjects made it!(author)2011-07-25

You could just mount a servo on top of the can of WD-40 to press it down.  It should spray far enough by itself if it has a straw on it.  Also, you would have to use some sort of electric ignition device (way too fancy of a name), like a wire that gets hot or a gas grill sparker, because they wouldn't let you have a candle on your robot.  Most competitions don't let you have flamethrowers at all.

sampson111 made it!(author)2011-01-26

why dont u hav wheels on the front of the robot i im making one too ill take photos and put them up

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Bio: I like regular robotics and combat robotics. I also like just about anything that has to do with instructables.
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