FAQ's
Updated 08/29/2002

These are the questions most often asked by newbie builders. I've put them in rough order based on how often they get asked. And they get asked A LOT! Seriously. PLEASE read this stuff first. In fact, the first version of this FAQ was written nearly two years ago and 99.5% of it still applies. The only changes I've made are to update links, provide some new information about the changing technology we can buy off the shelf, and to add some new competition information. If you email me a question that's answered here, I will probably ignore you or refer you right back here without comment. I mean it. Don't do it. Don't even think about it. Ahah! I caught you thinking about it!

Q1. This is pretty cool. I want to build a robot but I don't know how to start. Can you help?
Q2. How much money does this take?
Q3. Wow, it costs a lot. How do I get a sponsor to give me money?
Q4. I live in Sometown, USA are there any competitions near me?
Q5. Where do I get parts for my robot?
Q6. I have an R/C car, can I start with that?
Q7. What about using my Radio Shack radio transmitter?
Q7a. What about my R/C Glider Radio?
Q8. OK, you convinced me, what kind of radio should I get?
Q9. What's an ESC? Do I need one?
Q10. What is this "Tank Drive" and "Channel Mixing" stuff that everyone keeps talking about?
Q11. Wow, there are a lot of parts, how do I hook them all up?
Q12. Can I put a flamethrower, Taser Gun, or Liquid Nitrogen-Freeze Ray on my robot?
Q13. How big can my robot be? Is there a size limit?
Q14. I have questions not answered here. Can I ask them on the Battlebots Forum?
Q15. Okay, I've read the rest of the FAQ, NOW will you tell me where to get parts?

Q1. This is pretty cool. I want to build a robot but I don't know how to start. Can you help?

A.   Yes, but only if you REALLY take my advice! First, read this entire FAQ. C'mon, its not that long. Next go to my list of other "HowTo" sites and read each and every one of them. When you've followed all of those links, and all of the recursive thinks from there, chances are you could actually build a robot!

Q2. How much money does this take?

A.   There's an "old joke" from the Battlebots forum that answers this question. "All of it!". Seriously, this is not a cheap thing to get into. The average lightweight can cost at least $1000 and some of the super-heavyweights are rumored to cost tens of thousands of dollars. If you're a paperboy, fry-cook, or on a similar budget, I HIGHLY advise you to stick to the lower weight classes or even BEAM Robotics. They are every bit as fun, but the incremental cost is usually less since you're buying less and smaller... Its not that it CAN'T be done for small amounts of money, its just that its usually not done for less. A good radio and speed controller alone will usually set you back somewhere around $500, give or take. Motors, Batteries, and industrial/precision components like pneumatic cylinders, linear actuators, etc. are the next most expensive items.

Q3. Wow, it costs a lot. How do I get a sponsor to give me money?

A.   Sponsors are a tough business. Usually, you have to be able to demonstrate to the potential sponsor that they will get something out of helping you. Simply emailing the webmaster at your favorite company and saying "Hey I'm going to build a robot, can I have some money?" is going to get you nowhere. If you're serious about getting a sponsor, I recommend you do as many of the following as possible:

  • Finish your design, and consider starting construction BEFORE you approach anyone. A potential sponsor will be more impressed if you've got SOMETHING, which is better than NOTHING. Even better would be another working robot that you built WITHOUT help, so you can prove you can do it.
  • Better yet, build and campaign your first robot. Preferably, you would do a good job, and maybe even place. Nothing draws help like proving you don't need help.
  • Write a proposal specifically for the company you're interested in. Be VERY clear about what YOU WILL DO FOR THEM and WHAT THEY GET OUT OF IT. The more specific this is to the company, the better. For example, I offered to one of my sponsors that I would bring the completed robot to local schools to help get kids excited about taking science classes. This was right in line with that company's "mission statement". Cite examples of the media coverage they're likely to enjoy, and who will see the coverage. In short, MAKE IT LOOK LIKE A GOOD DEAL FOR WHATEVER THEY GIVE YOU. They're not in this for charity, they want to get something out of it.
  • Consider NOT asking for money. Instead, could the company help you by donating time, materials, or expertise? One of my "unofficial" sponsors helps me out with shop time when I need things turned on a lathe or what-not. This doesn't cost him anything but electricity, but its a HUGE help to me. Rather than asking for $400 cash, maybe a company could donate a couple of motors that would cost you $400 but it only costs them $200 to give away. See where I'm going with this? There are a lot of things you can get that will make it cheaper/easier for you to build the robot that don't neccesarily cost someone big money.
  • Be smart about who you ask to sponsor you. Lets be realistic. The guys who work at Vantec probably have 200 people a week asking them to be sponsors. If you fire off a proposal, you're just going to be one more builder, especially if you don't have a working bot to prove you can be a winner. Think instead about asking local companies who don't actively sponsor anyone, or your place of business, or even your school or community association. Use your local status to your advantage. People are much more likely to get behind someone they've met, who is from their "home town", than some faceless email name at a keyboard.

Q4. I live in Sometown, USA are there any competitions near me? I'm in school so I can't travel very far...

A.   Since the time I originally wrote this FAQ, quite a few new competitions have sprung up. This list probably isn't comprehensive, but should help you get started:


Sorry, but that's it. If you live in Nebraska, or Texas, or wherever, there's not really a competition near you. Just pack up a truck (or luggage and fly if its a smaller bot) and head on out. If several heavyweight competitors from the UK can make it to every Battlebots Competition on the West Coast with a 210lb robot as luggage, you can make it a thousand miles across the states...

Look, it costs a lot of money to put one of these events on safely. The "Battlebox" originally cost over $100,000, not to mention that it takes three full cargo containers to move it. No one is going to spend that kind of money to pick up and move the competition across the country just to satisfy a few people. Especially not when many of the more seasoned builders are willing to COME to the competition, wherever it is.

If you're the organizer or you know of another Robot-Battle competition that you'd like listed here, and it uses similar rules and setup to Battlebots/BotBash/CJRC (I don't desire listing BEAM, Sumo, etc. competitsions here), then email me at mikeh@puppetmaster-robotics.com

Q5. Where do I get parts for my robot?

A.   Whoah! Slow down there. I bet you've got a few more important questions to ask BEFORE you start buying stuff. I always reccommend that someone be REALLY sure about what they're building before they start buying stuff. It minimizes the amount of money you waste on motors, parts, etc. that you'll never use. Trust me. At some point I'm going to have a garage sale of the hundreds of dollars of stuff I bought that I won't use. Tell you what. At least read the rest of the FAQ and then maybe I'll tell you where to buy stuff.

Q6. I have an R/C car, can I start with that?

A.   Yes and No. Unless you only plan on entering the 12lb weight class at BotBash or CJRC, the components just aren't up to the abuse and they won't be competitive. A purpose built machine will almost always do better, but don't let that stop you from putting spikes on your RC-10 and coming to BotBash, it will still be fun!

The other thing you can do with off-the-shelf RC components is the new 1-pound robot class called SOZBots (Sixteen OZ roBots, also called "Antweights" in some circles). Many of these are made with hacked RC servos and motors and these can be inexpensive to build but still be VERY exciting to fight with and watch.

Q7. What about using my Radio Shack radio transmitter?

A.   Again, no. Most competitions REQUIRE at least an FM radio these days. Most cheap TX's are AM. Again, you MAY be able to squeek by the rules with an AM, but you're likely to have so much trouble controlling the bot that it wouldn't be worth it anyways. I HIGHLY recommend that you make investing in a good quality FM or PCM (better) radio your FIRST priority if you're going to compete. Its one of the things that you will re-use the most, and as long as you don't abuse it, you should always be able to recoup most of your investment if you decide that this sport isn't for you and you want to sell everything. Again, if you can afford it, spend the extra money for a PCM radio, it will serve you in good stead if you ever upgrade to the heavyweight classes...

Q7a. What about my R/C Glider Radio?

A.   One of the big changes that's gone on since the original writing of this FAQ is that all (or nearly all) of the sanctioned fighting competitions have begun enforcing the FCC's rules on Ground vs. Air frequencies for Radio Transmitters. This means that your 72MHz air radios (like for gliders, planes, and helicopters) are no longer allowed. The good news is that unless you bought a comlete piece of junk (see question 7), you can probably have the radio retuned to the legal 75MHz Ground Frequency band. Team Delta recommends D & M Electronics for this, but I haven't used them yet.

Q8. OK, you convinced me, what kind of radio should I get?

A.   I won't get too much into different brands, but these are the features you'll likely need as time goes on:

  • At least 4 channels, 5 or 6 is better. You'll only need 2 to drive it, but you never know what kind of weapons or other special systems you'll need to control...
  • One more time, PCM if you can afford it. It gives you an extra margin of safety against losing control of a potentially lethal robot. My Futaba radio is both PPM (regular FM) and PCM compatible, so I got it cheap up front with an FM receiver and I can upgrade to PCM later for only the cost of a new receiver, instead of a whole new radio.
  • Dual Rate controls - not required but sometimes helpful, depending on the competition. BotBash always has some sort of obstacle course driving test every year. I find being able to use a dual-rate switch to dial back the speed/responsiveness helps to navigate in a more controlled fashion. Could also be used on some radios as a quick servo-reverse if you have a bot that runs upside down and you want to reverse the control directions...
  • Mixing/Computer radio - another nice feature that isn't required for those builders on a budget, but is worth considering if you only want to buy a radio once in your life. A radio that can do Elevon mixing will help if you ever want to do tank-type steering but aren't using an ESC with built-in mixing (like a Vantec). Other mixes might be helpful if you have a complicated or unique weapon. Memory for multiple vehicles is also helpful if you have more than one bot and you don't want to have to reprogram the radio each time you switch. My Futaba 6XA does all of these, including a 3-model memory.
  • Don't forget to get the radio in the 75MHz band. Some retailers will do the conversion for free if you buy from them. Other places sell pre-converted or factory designed ground radios. Or you can buy a used Air-Frequency radio cheap and have it converted. However you accomplish it, you MUST have a ground-tuned radio.

Q9. What's an ESC? Do I need one?

A.   A speed control, or electronic speed control (ESC), is the interface between your hobby R/C radio and the motors in your robot. Most competitors, probably 90%, use electric DC motors to drive the bot. You just can't hook the receiver up to the motor, you have to have something that the receiver can talk to in order to control how much power goes to the motors. There are several types of controllers, but many people use a controller with a cable that plugs right into the receiver. These are either true R/C ESC's like a Tekin, Novak, etc., or one of a line of specialized controllers from a company like IFI Robotics or Vantec. For a beginner, I highly recommend a one of these since they will plug straight in. The Vantec's have build in Tank-Mixing, the IFI products require an outboard mixer, but are a little cheaper

There are other speed controls, for example 4QD, and some smaller companies making controls for wheelchairs or golf carts. These sometimes require a "little extra" though, since often they are a single-channel controller (you would need two) and they don't provide any mixing for you. Also, they are not usually plug-and-play compatible with a Hobby Radio receiver. RC Interfaces for the 4QDs, along with several other switches and controllers can be found at the Team Delta e-Store. The mixing function can be done on your radio (if you have a good one) or with an outboard mixer (see next question).

Q10. What is this "Tank Drive" and "Channel Mixing" stuff that everyone keeps talking about?

A.   "Tank Drive" is the most common way to drive the robots. It involves two motors, one for the left and one for the right. Turning involves slowing or reversing the inside wheel of a turn while the outside wheel turns forward at speed. For an excellent graphical explanation of tank drive, please visit Jim Smentowski's FAQ here.

"Mixing" is the radio signal manipulation that has to take place to make Tank Driving happen with only ONE JOYSTICK, as illustrated on Jim's FAQ. Mixing can be done on the radio (Elevator-Aileron (ELEVON) mixing on an aircraft radio), at the output of the receiver (using an outboard mixer such as the IMX-1 ESC Mixer from Team Delta/RobotLogic, OR, at the Speed Control (ESC) itself, such as with a Vantec.

You don't NEED to do mixing electronically. The other option is to use two joysticks and "mix" them in your head. This was how early tanks were driven and even some video games (think Battlezone) use this interface, so its not difficult to learn. Instead of a joystick that goes Front/Back/Left/Right, you need two joysticks that go Front/Back. Each joystick controls one motor. If both sticks are forward, it goes forward. If both sticks are rearward, it goes backwards. If the right stick is forward and the left stick is centered or to the rear, then the bot will turn LEFT, and Vice-Versa. Get it?

Q11. Wow, there are a lot of parts, how do I hook them all up?

A.   Here's diagram that might help, showing a basic 2 motor robot and a third channel to control a weapon. The 4 channel transmitter uses Radio to Control the Receiver (RC, get it?). The receiver then breaks down the control input from the 4 channels into the transmitter into 4 output channels. In this setup, channels 1 and 2 are on the right stick on the transmitter, and they are connected to the Vantec speed controller in the robot. The Vantec does the "Tank Mixing" as described above, and sends PWM (pulse width modulated) control voltage to the Motors. This allows proportional control over the motor speed. Give it a little bit of stick, the motors turn slow. Give the transmitter full stick and the motors go full speed.

We also have a third channel hooked up to a Team Delta electronic switch. Depending on which model you have, you could use the switch to control the arm motor for a lifter, a saw motor, or even the solenoid valve to control a pneumatic spike, like I used on Scarab. I've left off the weapon here, but you should be able to figure it out.

On the fourth plug, you can see that the receiver has a seperate battery hooked up. I like to use a separate receiver battery since I want to make sure that I don't loose control if the drive batteries get low. If this isn't a problem for you, then you could use a battery eliminator to wire the receiver directly to the main batteries. Also, you're probably wondering, "Where's the fourth channel if the battery is connected?" Some receivers don't have a separate battery plug, so they share it with one of the channels. Many people don't even use that last channel, so this isn't a big deal, but if you DO need to use that channel, you will need a "Servo-Battery 'Y' Cable". These are easy to find at your local Hobby store.

Q12. Can I put a .357 Magnum, Flamethrower, Taser Gun, EMP Generator, or Liquid Nitrogen-Freeze Ray on my robot?

A.   No, the rules are very specific. Before you even start designing your robot, you need to read and be familiar with the rules for the competition. The BattleBots Rules, BotBash Rules, and NERC Rules have been created primarily for Safety and Entertainment reasons.

Safety is paramount, and most of the things that are illegal are because allowing them would put the builder/operator, the people in the pits, the arena, and the crowd at undue risk. The last few rules address Entertainment-Specific concerns meant to make sure that fights are exciting and worth watching. They have evolved out of what worked and what didn't work. For example, nets and entanglement devices used to be allowed, but they made for boring fights and cut down on the use of crowd-favorite weapons like saws, so they were banned. If you REALLY have a problem with the rules, you can write to the appropriate rules committee, but don't expect great results.

Q13. How big can my robot be? Is there a size limit?

A.   For most competitions (except the NERC 12lb class*), there are NO official size limits, only weight limits. Please read the rules for the appropriate event to see the specific weight categories. (See question 12).

HOWEVER, there ARE some practical limitations to robot size:

  1. Your robot must be able to FIT THROUGH THE DOOR. In the case of the BattleBox, the door is 8ft wide at the top of a long ramp. If you have concerns about your design, email the appropriate rules committee to get measurements for the opening, etc.
  2. In the Battlebox, the Arena-Hazards are built into 4ft square modular sections (as are the regular floor panels) and they can be ANYWHERE. If your bot is much wider than 4ft, you may have trouble driving between arena hazards without getting nailed.
  3. You have to be able to lift/carry/transport the robot. If you can't fit it in your truck, in a box, or whatever to get it TO Battlebots, then you're sunk. If its a strange shape and can't be easily carried by you and your team mates, then you won't be able to compete. No one is likely to help you get something like this into the arena. Also, remember there are maximum numbers of people on a team, so you can't just have 20 of your closest friends help you bring the thing into the arena...

*NERC Imposes an 18"-cube size limit on its "Hobbyweight" (12lb) class due to the small size of the original fight enclose in use. (Larger bots had no room to maneuver.) This limit is still in place, contact NERC officers for enforcement details.

Q14. I have questions not answered here. Can I ask them elsewhere?

A.   Yes, there are many good places to get more information. Some of them are The BotBash Forum, OverVolt.net, and the waning Delphi forums, but unless you own some asbestos underwear, or actually like getting Flamed or ignored, please, please, PLEASE consider a few points of etiquette:

  • Make an honest effort to research your question before asking it. You would be surprised at how many times a week questions like "Where do I buy motors?", "Do I need a speed control?", etc. get asked. These are not entirely unreasonable questions, but they have been asked and answered so many times that people grow tired of answering them. So instead, they usually flame the poster or just ignore the question altogether. Look for the answer in FAQ pages, on builders sites, or even use the "Search" tool on the available fora. Chances are, you'll get a more thorough answer by reading the first or second time it was answered anyways.
  • When you do ask questions, make them as specific as possible. No one wants to try to answer "How do I build a battlebot?", its too vague and would take a week. On the other hand, a question like "Should I buy a Futaba 6XA or 6HA radio for battlebots?" is a good one. It shows you've put some effort into finding an answer, and people will usually be glad to offer opinions on the subject.
  • Use a real-name username for making your posts. Unlike much of the internet, people in Battlebots usually end up meeting one another when it comes time to compete. Making posts from behind "KoolDude1" is a lot harder for people to relate to than "JohnPublic". At the very least, use something that identifies your team. You will get more respect and people will relate your online persona to your real life persona easier if they can tell who you are.
  • Build First, Talk Smack Later (or not at all). By and large, veteran builders are very uninterested in seeing drawings, 3D models, etc. of a bot you're "going to build". Its better to get something built (or in the process of being built) and post pictures or a web-link if you want builders to see what you're working on. This goes hand in hand with making statements like "My bot is gonna beat all of you!". That's just lame. If you're going to beat someone, show up with a bot and do it. It does no one any good to post "I've got a killer robot all designed and all I need is money to build it so I can kill you all!" It just makes you look stupid and will get you added to someone's "ignore" list.
  • Use english. Don't shout. A VERY high percentage of builders are scientists or other educated people. We prefer clear, plain english questions and answers. Emulated ghetto-speak, "733t"(leet) or netspeak (hey peepz! ne1 no where I can get sum motorz?) doesn't endear you to the population at large. It makes you annoying, and will get you ignored or flamed. THE SAME GOES FOR SHOUTING! DON'T SHOUT YOUR QUESTIONS... see its annoying when people shout. Caps are good for emphasis, but an entire message typed that way gets hard to read. Good spelling and proof reading are also a plus. I know you're in a hurry to get an answer, but taking an extra 10 seconds to re-read the message just to make sure its clear will mean all the difference.

Q15. Okay, I've read the rest of the FAQ, NOW will you tell me where to get parts?

A.   Yes. Check out the Parts and Radio sections of my Links page. Every time I buy from a new company I try to add it to this list, so if I bought it, I probably bought it at one of those places!


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