Evil Robotics

4 ft x 4 ft SOZ bot Arena

    Are you are thinking about building an arena?  I sketched out some basic plans for a 4 x 4 foot plywood base platform with side walls.   I recommend making the side walls out of 1/4" thick Polycarbonate.  At a minimum maybe you should use 3/16 thick.  This total price will be based on how cheap you can find a source for Polycarbonate.  

      To see the design plans click here to download a SolidWorks edrawing file.  It is 1.7 mega bytes.  An edrawing contains a self-extracting viewer.  Save it to your directory and then from within Windows Explorer double click on the file.  That should launch the self extracting viewer.  When it is up and running then click on the play button and enjoy the 3-D spin around views.  Please email me if you have any problems with this.    It was a design for the SOZ bot section of the arena.  

    The tools required are a circular saw, a tape measure, a drill, bits, and some wire strippers.  Of course a table saw is really nice.    If you are already building robots you have all of this stuff any way.

    I had some pieces of Polycarbonate in the garage that were 39 x 36 with 3" radius corners.  So I used what I had in stock.  For the arena floor, I think you could get away with using 3/8th inch thick plywood or white Cintra.  Plywood is allot cheaper but it is not as strong and not transparent like Polycarbonate.   Splurge and buy the better grade plywood.  Paint it to avoid getting slivers.

    If you want to use an EV Warrior to power a saw blade then you would want to use 2x4's to give you  extra  height.  Don't use carbide tips on the blade.  They will probably break off and send metal pieces flying into your eyes or face.  Obviously exposed saw blades are not appropriate for unsupervised children.  

    I think you could also use a standard RC car motor to power a small blade.  If you want to buy cheap ones call All Electronics at 1-800-826-5432 and get them to send you a catalog, or you can go to their web site at www.allelectronics.com.  They sell small surplus DC motors for about $3.50.  

    I used stuff I had collecting dust in my garage.  I made the weapon from a spinning Polycarbonate piece about 2 x 8 x .25 inches.  It was powered by a wheelchair motor with a right angle gear box, and ran off two 12 volt MK wheelchair batteries.   It spins about 230 RPM and is plenty powerful enough to damage one pound Battlebot toys.  My brother in law had a bunch of used wheelchair type stuff.

    The side walls were made 9.5 inches tall.  That size had more to  do with stock material size available than what we really needed.  The decking and side walls were attached using countersunk brass deck screws.  I put 2x4's under the plywood to tie it all together, and then the side walls won't separate from the main floor. 

    We built the arena in basically one day.  I had help from my 5 year old son.  We made it with four openings one on each side, 13" each.  I plan on adding a removable door on each so we can vary the number of cutouts.  

    The weapon motor bolted in pretty easy but it did not work at first.  The motor was missing contacts.   Luckily we had some exact replacements out of another motor.  

    We wired up a switch box to minimize exposed wires.  Inside we placed a auto resetting 24 volt fuse.  Great care needs to be used to insure the mains on the batteries are not shorted directly.  That would cause a high amp draw melt down.  Take a little extra time and cover all terminals with electrical tape or even better put the batteries in a wheelchair type battery enclosure.

    We have already fought about 40 matches with the new arena.  It is definitely better than a chalk drawn square on the concrete. 

Bigger arenas with over structure

    The real question is how big are the robots you are fighting, and thus how elaborate do you want the over structure?  If you have spinning weapons that throw debris then you will need a canopy.   If you want to see in, then Polycarbonate is the hot ticket item.  You may be able to get a cheap source for Polycarbonate sheets by talking to the MURC guys.  They found an incredible price when they built their fully enclosed 12 lb robot arena.

    Standard construction stuff comes in 4' x 8' sheets, therefore to get the most use out of sheets you should probably have a small 4' x 4' arena insert with a bigger canopy being possibly 6' x 6' or 8' x 8'.  You will want to make it in sections that are small enough to lift.  Maybe the bigger arena is just the over structure and the floor is concrete or wood but not elevated. 

    Do you ever expect a robot that is taller than 16"?  If not I would recommend using 24"  for the height of the walls.  That way you can get 2 side panels out of one 4 x 8' sheet.  Hinge pins and 2 x 2's may be a easy way to connect the panels together, rather than using bolts or screws.  It works great in waterbed type frames.

    If you can get a quantity of 4 sheets then your outer shell would be 8' x 8' x 2' high.  That may be bigger than your storage place.  Possibly you can build most of the setup but substitute some sections out of plywood in the beginning.  Wood is allot cheaper than plastic.  I think wood is better than steel, because it is cheaper and easier to drill holes.

    I have bought Lexan in Denver from A.I.A plastics but there price is pretty high.  They can cut to your final size.  If you are going to use this for the arena floor I think you cold get away with using plywood or Cintra instead.  It's allot cheaper but it is not as strong and not transparent.  

   I have also purchased Polycarbonate from North American Precision Parts.  843-293-8527.  They are out of Florida, but I have bought 1/2 thick from them on Ebay.  They probably have small pieces scrap and might be willing to sell you bulk orders.