How to Make a Smooth Lego Caster Wheel

Hey, Lego Mindstorms lovers! Are any of you tired of lousy caster wheels that hardly respond to your robot's movements? Also tired of having to use friction-causing skids? This is the solution to both problems. It is a smooth Lego caster wheel, made of two tires that rotate freely to give ultimate movement control. This occurred to me when I did First Lego League, our team had to use skids because our caster wheel was too uncontrollable. The skids gave our robot a disadvantage, as they caused friction, slowing our robot down and screwing up our measurements. 

If you need additional help, use the images for help. 


Parts required :
2 × 4514553 (Connector Peg with Friction, 3M)
2 × 4210751 (Technic 3M beam)
6 × 4211573 (½ Bush)
1 × 4211622 (Bush for Cross Axle)
1 × 4121667 (Double Cross Block)
2 × 4107085 (Angle Element, 0 degrees)
2 × 4142865 (2M Cross Axle with Groove)
1 × 4535768 (9M Cross Axle)
2 × Lego Technic/Mindstorms wheel of your choice. 



Good luck building this caster wheel!

Step 1: Create the First Hinge

Take the 9M cross axle and slide in one 3M beam down the middle hole. Put the bush down the center axle, then put on both 3M connector pegs on the two leftover holes. Slide on another 3M beam. The beam should click in place, held by the two 3M connector pegs. 

Step 2: Attaching the Second Hinge

Slide one ½ bush down the other side of the 9M cross axle. Then, slide the double cross block's center hole down the axle, then cap it off by sliding another ½ bush down the axle, where you want to leave a tiny amount of space to let the double cross block spin.

Step 3: Making the Wheel Turn

This step is perhaps the most important step in this Instructable. Repeat this step for both 0 degree angle elements.
 
First, stick the grooved 2M beam all the way into the angle element's cross. Then, stick one ½ bush on both 3M beam's ends. Stick one 3M beam through the hole of the angle element, then stick another ½ bush to cap your angle element. Using the part of the beam sticking out, put the wheel of your choice on that end. Be sure to repeat this step on the other angle element, or else you will have a one wheel caster wheel! 

Step 4: Put the Wheels On, and You're Done!

Now, using the 2M beam sticking out of the angle element, stick that into the double cross block's hole. Be sure that the wheel is parallel to the 9M beam. Repeat this step with the other wheel module and the other hole. Now, test your finished caster wheel by spinning it in circles. You're done with your caster wheel!   

Step 5: Inserting Your Caster Wheel Into Your Robot.

If your robot works with this caster wheel, it must have two parallel beams, separated by a distance equivalent to one hole, or one M. If you want to adjust the height of your caster wheel, slide the double cross block and both ½ bushes up and down along the 9M beam.  

Take off one 3M beam. Slide the two 3M connector pegs through your robot's beam's hole. Then cap the two connector pegs with the 3M beam. 

Have fun with your caster wheel!