Step 5: Computer Aided Design (CAD)

CAD is the system used by all professionals for the creation of the products you see and use everyday. It allows you to make 3D computer renderings, seeing how things fit together on the computer before you build. This step can revel potential problems on your bot which will reduce your time and cost overall.

It is a common thought that CAD systems are difficult to use and build if you are not an engineer or have been trained to use them through some class. Recent CAD software has been shifted from even five years ago so that they are easier to build models with a user interface that anyone can pick up and learn within a few hours.

Within industry the three most popular pieces of software are Autodesk Inventor, Solidworks, and Pro-e. Each one of these has advantages and disadvantages to their own right but all are comparable for this type of design. I will not be going into how to use CAD in this instructable but there are many resources online for using this type of software.

Buying CAD software can be very expensive but fortunately there are many opportunities for free licenses of software if you are a student, or if your company has licenses of the software.

Students can get autodesk inventor for free from http://students.autodesk.com All you need is an email with a .edu ending

You can also get a copy of student version of solidworks very cheep/ free from time to time online.
They also have a great tutorial for robotics design located here. http://www.solidworks.com/pages/products/edu/Robotics.html?PID=107

For robot design with little to no CAD experience I recommend Inventor or Solidworks both provide a simple interface, and more importantly there are lots of models available for free download. Stock parts like bearings, screws, motors, etc can be found. Using these models will save time when modeling.

The most important thing about CAD design is that you have your dimensions right. Now that may seem like a straight forward piece of advise but I see loads of people trying to make realistic renderings and spend too much time making their parts look nice instead of focusing on the real goal of CAD to make models which are accurate.

I am going to leave this step because if you take the time to learn CAD the process steps for design in the software become more apparent. If you choose to skip this step due to the inablity to run the software or the lack of interest I recommend a "cardboard template" method. Take cardboard and cut out scale models of each one of your parts for layout, before you cut your real material. A good example of this method in the webshow by revison3 called Systm located here http://revision3.com/systm/robots/

Ultimately the purpose of this design step is to minimize the mistakes with your expensive.materials.

Additional notes:
*modern CAD software can assign weight properties so you will know how much your bot should weigh before you build
*Ensure that you have sized things correctly so they fit together, for example a 1/2" shaft will not fit through a 1/2" hole. For exact machining you are dealing with thousands of an inch (.001") .
<p>what would you suggest, flamethrower, flippers or revolving blades?</p>
<p>I think flippers and or revolving blades</p>
<p>for one of the lower weight bots</p>
<p>Awesome instructable! I am looking at building a combat robot for a competition that will cost around $4700 US dollars, and will probably not be able to pay for it myself. Do you have any idea where I could get a sponsor?</p>
You show the design process really well! You really know your stuff! I am currently building my own combat robot, the blog is...<br> <br>http://eventorizon-maelstrom.blogspot.com/<br><br>if you want to check it out. Tell me what you think cos you definitely have the construction of your bots down to a fine art, especially cos you trust your own CAD skills enough to have the parts custom cut!
I built one, imo it sucks and i want to rebuild it. But i have no reason to... To me it seems combat robots are dead, except for a couple annual matches in CA and FL. All the websites on combat robots don't seem to be updated since 2002. (bad grammar) Now, i have this crappy bot sitting in my garage, and i have no idea what to do with it. I could use all of the electronics to make something, but what?<br />
Science is Best in the world
Robot Battles (http://robotbattles.com/) in the southeast US is still going stong.
Most of them are, unfortunately. However, the RoboGames in San Mateo, California, are still on. Apparently there are 50+ events including combat soccer, and lego bots. Even if you don't want to rebuild it as a battlebot, you could probably use the components for a soccerbot or something.
<p>Whoo! Love the robots. Wish I could build one. Go to cameltalk.webs.com or puttyfun.webs.com!</p>
I am making it but l Love making Roberts
<p>I found a great online resource to browse and compare similar products: http://www.archiexpo.com/tab/computer.html</p><br> <br>
im building a three pound robot but I don't know what the weapon can be so I need advice on what the weapon can be also this is my first battlebot
what is fabrication needed for I saw some of the other robots and one of the steps was fabrication I don't know what that is <br>
for a 3 pound robot what do you think the weapon should be I need help on this one
I want one that talks, fights, and does anything for me
Robot combat... we train them to be fighters, then when they get smart enough they revolt for us making them fight. Nice Instructable. I'll definitely be building this in my spare time.
thatz cool
I'm trying to build one of these this summer. Do you think piston-mounted spikes would work or two horizontal blades?
I was doing a similar project and I found that when I used an AE-MDL-DualusDC chip I got the best results. This chip is extremely small and has a lot of power in it (1A RMS, 2A peak, per H Bridge). It has connectors on both sides that give you access to all the control and power signals. It also has SMT pads, that you can solder your own wires on, which is what I used. Here&rsquo;s more info about the chip http://www.avayanelectronics.com/Products/AE-DualusDC/AE_DualusDC_Manual.pdf . I found some really cheap ones at DriverDudes.com, you can get just the chip or have it fully assembled. Here&rsquo;s the link http://driverdudes.com/product_info.php?products_id=32
which type of motor should be used for cutter?
what does the orange robot do at the top of this page
how do u make the round one can u put steps on this website
would this be a good idea 2 circular saws on sides <br>nailgun on top <br>made of stainless steel <br>and a spiked rammer with a strong motor too power it <br>how much do u think it would cost plz reply
Could i just buy one simple rc car and get the inside and change the armor and put a weapon. because im cheap :D
what about programing it? where does one begin with programming?
That won't be necessary if you build with enough hardware. RC receivers don't need programming and neither do the servos. The relays, maybe, but the robots aren't autonomous.
can i just put the fuse between the wires, instead of having a breakout board??
Hi!<br/>I was wondering..... where could you get a base- where did you get yours?<br/><br/>I've all ready seen<br/> <a rel="nofollow" href="http://www.inertialabs.com/">http://www.inertialabs.com/</a><br/><a rel="nofollow" href="http://www.robotmarketplace.com/store.html,">http://www.robotmarketplace.com/store.html,</a> <br/><a rel="nofollow" href="http://www.battlekits.com/">http://www.battlekits.com/</a><br/><br/>P.S.-I'm trying to build a drum bot.<br/>
I built mine. Get raw aluminum plate and cut it out. If you don't have access to fabrication tools (mill, waterjet, laser, etc) you might be better off buying a pre-made base. The trade off will be that you will have to make do with what you can buy instead of doing a custom solution.
would you be willing to make this c.a.d downloadable?, i recently received a autodesk setup and id really like to see a properly made fighting robot cad (thats what i intend to use it for) befor i make mine so i get a basic idea of what to aim for, ta :)
I would be glad to give you the CAD models for the machine as soon as I get a chance to find them. They are on some portable hard drive somewhere as I have changed computers since then. email me greg at robogreg dot com and I will do my best to send them to you.
hi, i sent a email...wondering if it got through?
I got it. I am working on finding the files when I get some time.
Why do I need a Breakout board???
you need a breakout board if you want to use any type of fuses to protect your speed controllers.
about how much money would a mantisweight battlebot cost if i had if ihad like the crapiest matirials&nbsp;for it and how much would it costif i had the best matirials on it.<br /><br /><br />
unfortunately, i have highly limited resources, a max of $200 at any given time, if i'm lucky. :<sub>V</sub>(<br/>
it is possible to build a bot with 200. There are plenty of cheap components. You could build a sub $200 bot using motors taken from Harbor Frieght $15 drills. Use the battery packs from the drills to power the bot. For remote controls you can find some cheap things on ebay and from a company called GWS. You can view some of their components on <a rel="nofollow" href="http://www.banebots.com,">http://www.banebots.com,</a> which is another source for inexpensive robot materials. <br/><br/>For sub 200 robots you will be looking at the 3-12lb range of classes.<br/>
i suppose you have a point, but i would still need to buy tools, or find a place with drill presses, plasma cutters, etc.
Never under estimate what you can do with hand tools. While I have the advantage of working at companies with cnc, laser cutters, and waterjet. I have seen many robots built with just a hand drill and a jigsaw. If your budget is really limited you can see what you have lying around or parts that are within your budget and build around them. Getting one of the CAD software packages and learning through that will enable you to print out full scale flat patters which you can trace and cut with a dremel tool, jig saw or any other device. I have done this method for even large scale items using a plotter. It works wonders for frame welding layout and sheet metal parts.
i am a 14 year old thats big on rc and you are totally right.. i use only hand tools and i have done things that would usually require a drill press, a vice, etc.
You are <sup>A</sup>W<sub>S</sub>O<sub><sup>M</sup>E</sub>!<sub> You just won't give up until I make a robot monster thingy, will you?</sub><br/><br/>ps: how do you set up a wireless remote? my dad couldn't help me...<br/>
CAD is an expensive and fairly large program so on a fixed budget that might not be the best route. But google has a program called Sketch-up that is very similar to CAD and its free. Its fairly easy to get started on as well.
There are also free versions of CAD, if you hunt around a bit.
probably. but if you also don't want to dedicate a good portion of your memory to just CAD this is a smaller alternative.
No doubt. But most light users would likely not feel it necessary to have other programs running at the same time. So it shouldn't be a huge issue. As for hard drive space, I don't know if I've ever seen a CAD program that was even a gig (unless it had huge libraries added to it). I haven't anything negative to say about Sketch-up, haven't ever used it. Was just letting the traditionalists know they had an option. Pro CAD's are the way to go, really. If you're gonna use CAD. Quality of work and ease of function more than make up for cost.
I concur.

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Bio: Mechanical Engineer with a degree from the Rochester Institute of Technology. Greg has been involved in almost every form of competitive robotics on the planet ... More »
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