Introduction: Mars Rover Key-chain

This is a fun little rover to weld. Made from nuts, some metal scraps, and a bolt, this is a key-chain model of a martian vehicle. Its not too heavy, but just heavy enough that you won't forget your keys.


To complete this project you will need these materials and tools:

  • A steel bolt (any size).
  • Six steel nuts that fit the bolt.
  • A steel marble or ball.
  • Eight inches or so of 1/8'' thick steel rod.
  • A welding machine and equipment (preferably wire-feed).
  • Two key-chain rings.

Step 1: Cutting and Arranging

To begin this project, clear off your workspace and put your parts in a pile nearby. To begin, lay the bolt flat on one of its sides. Then, set the nuts in two rows of three on both sides of the bolt. Like in the first picture. The nuts are going to be your rover's tires. Lay them out until you like where they are. Remember, this is art not science, so tweak it until you like it. Once the nuts are where you like them relative to the bolt, slowly pull the bolt away so as not to bump the nuts. Very carefully estimate the length between the middle of one nut to the middle of the nut across from it. Remember this length. Take the 1/8'' thick rod and cut it with the hacksaw into 3 segments, each as long as the length you measured between the nuts. Each of the rod segments is an axle. Gently slide the rods so that they are positioned like axles, one between each set of wheels (like in the picture).

Step 2: Welding on the Axles

Turn on your welding machine and get ready to weld. Tack weld the axles to the nuts from the inside. Once each one is welded on you should have three sets of wheels (pun alert) ready to roll. Before moving any of the wheels weld the nuts together where they are touching. Only small tack welds are needed.

Note: If you are using a wire-feed machine the wire feed may push the axle out of place before the arc starts. To solve this start the arc on the nut and move it to the axle.

Step 3: Welding the Body/Bolt

Take the wheels and turn them over so that axles are facing up. Take the bolt and place it on top of the axles so that the bolt head hangs off the front of the rover. Very carefully tack weld the bolt to one of the rear axles. Now, flip the rover over and properly weld the bolt to the other axles from the bottom.

Note: While welding be careful not to melt through the axles all the way or the wheels will move out of place.

Step 4: Welding the Cockpit On

Find the steel marble and hold it with your pliers. With your weld gun in one hand and the pliers holding the marble in the other, hold the marble on the top of the head of the bolt. Tack weld the marble onto the bolt head from the back like in the picture. Only a small tack is necessary as you will add more later.

Note: I would recommend keeping water nearby to cool down your rover every so often so that you can pick it up with your hands or gloves.

Step 5: Welding the Body and Key-chain Ring

Start a weld bead on the back of the rover's bolt and weld until you touch the back of the marble/cockpit. Allow the bead to cool down for a second and put another bead on top of that, and another, and another, until you are satisfied with the shape. Feel free to add weld beads wherever you want to enlarge the body. Take your pliers and pick up one of the key-chain rings. While holding it in place with your pliers, weld the ring onto the tail of the rover. Now that you are done welding let your rover cool down and then you can connect the second ring to is so that you can connect it to your keys or whatever you want. If you feel like it you can polish it with a grinder or sander and oil it so it wont rust.

Note: When welding the ring onto the body use very low settings on your welder or you will burn right through the ring and ruin it.

May you never lose your keys again. Thanks for reading.

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