MatchBox 220

Matchbox 220

Starting on a new project,a 220lb, heavyweight class combat robot. It will be constructed with a 4130 tube steel chassis, of various sizes depending on the location, and floating 0.19″ 4130 steel armor. The invert-able tank style drive powered by two long mags (Amp-Flow A283400 motors) triple reduction totaling 15:1 on 3/4″ drive shaft with stamped steel bearings. The drive will be controlled by four Victor 883′s and two 22.2v 5000mah 40-50C Turnigy Lipos. The weapon, a drum, will be powered by four EV Warrior motors. It will be approximately 8.5″ tall, 34″ long, and 47″ wide (Including wheels and wheel shield, 34″ long without those components).

MAG-S28-400_lg Bosch_EV_Warrior victor883 Turnigy5000

While I’m waiting for the parts I ordered to trickle in, I did have the Victor 883’s I’ll be using for Matchbox’s drive. So, I stuck them in an electric box and wired them up.


Pictured above, is half of the esc’s used for drive. I will be using one of these boxes per motor. (**I’ve decided to use one large box, rather than individual drive boxes, this configuration will just be for testing purposes.)

Before I go too much further, I want to take a side track and explain that Matchbox 220 will be using XT-90 connectors for all it’s li-poly batteries. (Pictured below.) The XT-90 consists of gold plated spring plugs nestled in an extremely tight fitting nylon shroud. It requires a lot of force to pull these apart, and that’s always good in combat robotics.

IMG_7893 XT-90

Back to the drive. So, here is one of the mags getting it’s round headed electrical terminal connectors crimped on! (Ignore the pink shrink wrap, I’m waiting for my red to come in.)


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I had someone ask why I needed shrink wrap at all, if I had the yellow housing. As you can see pictured below, the long mags I got from the Robot Market Place come with about an inch and a half stripped off the top of the mag wire, so I would have to cut off about an inch of the wire, or just stick some shrink wrap on it to keep it from shorting if it comes in contact with something conductive.


Below you can see one side of the drive wired up for testing. I’m using a Team Whyachi Power Switch, the 22.2 V 5000mah 40c-50c Turnigy li-poly, the two Victor 883’s, an “Orange Receiver” from hobbyking (which I will later switch to the specktrum ar6115e I have sitting in my box of goodies) with a 7.4v ni-mh battery, all hooked happily to the long mag.


Most of the pieces, add two batteries, a few more bearings, etc. Starting to look like a robot though!

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If you’ve noticed, I’ve been avoid the weapon design until I absolutely had to face that obstacle, as spinners and I have had a rocky past. With only 46 days left until RoboGames 2013, I finally finished collecting the parts for my main drive train, and was stuck with nothing to do except face the weapon problem.

Luckily, I had an epiphany!


What you’re looking at above, is four pieces of 2″x2″ square tube steel welded together to make a structure I can spin using the 4 ev warriors, as long as I can mount it.

This is what I’ve come up with to mount those four pieces of 2″x2″ square tube steel, the plate portion of the weapon will be mounted by bolts that will go down the entire length of the four 2″x2″square tube steel. Of course, the v-belt pulley will go onto the shafts there (which will be keyed)


The finished result will look something like this only with four bots to hold it all together.


complete weapon

Here’s the old vs new mock-up of Matchbox.


One of the wonderful things about being a builder? Outside consultation when you post stuff like that weapon design above. My favorite outside consultant, Chris Williamson, came back with a design that made mine look like a kindergartner’s finger paint next to the Mona Lisa… in other words, we’re going with his design.

weapon design

Which also brings us to the new body design:


My cad skills are not up to Chris’ standards so I can’t make the individual bars on Matchbox’s weapon, but it is adjusted to size, and placed with the shaft going through the entire length of the weapon.

Speaking of my lack of an engineering degree; Ryan Archer offered his services to stress test my weapon design and the results were just wonderful! ” 500lbs force directly to the middle of one of the bars still has a factor of safety of 16.4″ ; In otherwords, it’s going to take a beating and keep going. I couldn’t be happier. Plus, he made it a cool color….


I’m taking a break from the weapon, as I haven’t ordered the material I need yet. I’m circling back to the drive train. My project is to figure out a way to attach the sprocket to the wheel, as both the axle and the bearing on the wheel are live (meaning they will both spin). I’ve decided to make a 5 bolt pattern drilled out of both the wheel hub and the sprockets that will be bolted together!

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I got my framing and armor material in!

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Time to start laying it out and making cuts!

It would seem I have a “helper” as well.

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I want to show you my perfect example of “Do NOT try this at home, because FIREHAZARD”


Luckily, there was no fire, and it works awesome. Now to hook up four more batteries and try it again! (**Side note, To the people asking what happened to the heat-shrink: My cats knocked the battery off the counter and I was terrified it was going to explode the next time I charged it, so I took most of the heat shrink off so I could watch the individual cells and make sure they weren’t getting swollen.)

Tonight I’ve decided to construct the entire robot from wooden dowels, since I want to be sure how long to cut my framing.

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