Introduction: K'nex RC Floor Cleaner

This Instructable will show you how to make a remote controlled floor cleaner, kind of like a small version of the big floor cleaners that you would see at the mall. This project is based off those. I will show you how to build it in two main parts: the front and the back. These will be connected together near the end.


  • Spinning sponges to scrub the floor.
  • A rubber wiper to wipe up excess water.
  • A dripping system to keep the sponges wet.
  • Forward / Reverse acceleration and Left / Right steering

How It Works:

The sponges in the front spin to clean the floor as the cleaner drives forward. The bucket at the top feeds water through the tube to drip on to the sponges to keep them moist. Finally, the rubber wiper wipes up extra water.

Extra Notes:

  • Be care full not to get water on any electronic parts.
  • I find it easiest to fill the bucket by pouring the water first into a bottle then pouring it from the bottle into the bucket.
  • You may want to add a little bit of floor cleaner to the water in the bucket like you would when filling a bucket for mopping. However, be sure to use less cleaner because you are using a much smaller bucket.

Special parts that you will need other than regular K'nex pieces:

  • A K'nex Motor
  • A squeegee (with or without a sponge. I know that some have sponges attached to them and some do not. if you get one with a sponge then you can use that sponge for the scrubbers instead of getting others.)
  • A sponge or multiple sponges depending on the size. (see step 18 for details)
  • A small bucket or tub that holds about a liter.
  • Some small tubing.(see step 19 for details)
  • A little bit of rubber like from a bike tire. (see step 11)
  • One old RC car that has left / right steering and forward / backward motion. The important part to be working is the main circuit board receiver on the RC and the remote controller.
  • A DC motor with a gear box and axle for the wheel drive. (picture in step 11)
  • A 180° servo. The kind that you will need is a little bit different from most because it has two wires (instead of three) and can only be turned on or of (instead of being able to be set to a specific point). Summary: its more like a DC motor with a gear box but has a rotational limit of 180°. This type of servo is used because the RC circuit board from the RC car will reverse the current to change the direction of rotation. There is a picture of the servo in step 5.
  • If your RC car is still fully functional then you can still keep its steering and drive systems and use those instead. mine had only the main circuit board working so I had to use what is shown in the instructions.

Below is a video of the K'nex floor cleaner in action. Sorry about the pauses for turning, I had to drive it with one hand.

Step 1: A Note on the Coloring of the K'nex Pieces

I have a bunch of K'nex pieces that have different coloring than the standard colors that I have seen. Im not sure if this alternate coloring is very common or not so I thought that it would be good to add a picture showing the equivalent colors to help with building.

Step 2: Preparing the RC Circuit Board and Battery Compartment

  • Open up the top of your RC car that you have decided to use for this project..
  • Cut wired connections to the steering and drive. ONLY DO THIS IF YOU ARE NOT CHOOSING TO USE THE CAR'S STEERING AND DRIVE.
  • Cut off excess parts of the frame being sure to keep the area where the circuit board is mounted and the battery compartment. This will make it more compact and easier to fit in small places
  • Attach connection terminals to the wires going to the steering and the drive. These terminals make wire connections easy and I have found to be helpful for using the remote controlled system for other projects later.
  • You may need to extend the wiring for the drive as it is a little bit farther away and the wires might not reach.
  • Depending on where the battery compartment is on your car, I suggest installing the batteries now ( making sure that the car's switch is off) because later it might be hard to access the battery compartment.
    • The battery compartment on my RC car was underneath the circuit board so it was hard to access after the whole project was put together.

Step 3: The Main Frame Back Part 1

Here is the front part of the main frame of the floor cleaner.

My original design was So I took it apart and tried again and came up with this one.

Step 4: The Main Frame Back Part 2

Add the main circuit board and battery pack like shown in the picture.

The main circuit board and battery pack will stay more securely after the steering is added.

Step 5: Steering Part 1

To connect the 180 servo to the small white piece you can use a glue gun. I've found that this holds pretty well and isn't too hard to peel apart if you want to take it apart later and use the white piece fore something else.

My original Idea was to drill into the end of the K'nex piece and secure it to the servo with a screw. It didn't end well. I feel sorry for the K'nex piece. I later remembered that I used hot glue for the drip system. It was sturdy but could be peeled of of the plastic fairly easily. I thought hot glue could probably work well on the K'nex without destroying them.

Step 6: Steering Part 2

For the wheels be sure to add a thin blue spacer between each wheel and its corresponding red connector piece. Its hard to see in the picture but this will help the wheels stay in place and be more stable.

This steering system that I made was adapted from an attempt that I made at making an arduino car. The steering worked on the car but nothing else did. So I took the steering from that car and modified it a bit to allow the use of the larger steering servo that I needed to be able to use the steering system with the remote controlled system.

Step 7: Steering Part 3

Now you can put the first two parts of the steering mechanism together.

connecting some of the orange pieces can be a bit tricky. I highlighted them in the picture.

Step 8: Steering Part 4

Now you can add the third part of the steering mechanism and then it will be ready to be connected to the back part of the main frame.

Be sure to slide the servo into the orange box thing. this part helps holt the servo in place so that the wheels will turn instead of itself.

At fist I was using duct tape to secure the servo but it wouldn't hold stiff enough so i finally made this that held much better.

Step 9: Connecting the Steering

Be sure to connect the orange and black pieces pictured. this is what will hold the main circuit board and battery compartment in.

Step 10: The Main Frame Front

Step 11: The Wheels

I used rubber cut from an old bike tire to wrap around the drive system's axle so that it will fit in the wheel tightly.

Step 12: Connecting the Wheels to the Front Part of the Main Frame

Step 13: The Sweeper

The sweeper arms will spin when the K'nex motor is turned on.

The gray colored thick K'nex spacers in the pictures are each equivalent to the thickness of three blue thin spacers.

How the Moving Sweeper Came About:

Originally I just had the cleaner set up so that It had one wide brush that didn't move. I had been working on a K'nex ice cream maker at the same time which used a gear system that was very similar to the one currently used for the sweeper. It was used to mix the ice cream while it froze. I knew that the big floor cleaners like they have at the mall had rotating sweepers. I thought wheres the fun in having an un-moving sweeper when you can make them spin. So I modified the ice cream maker to hold sponges and attach to the main frame.

I found that it is very Important to use rechargeable batteries if possible because I had gotten to the final product and was about to film the floor cleaner in action when the batteries for the sweeper died. :)

Step 14: Attaching the Sweeper to the Front Main Frame

Step 15: Connecting the Front and the Back

Now you can connect the Front section to the back section like shown in the pictures. :)

Step 16: The Wiper

Remove the rubber part of the squeegee from the rest.

Drill three holes in the rubber part of the squeegee spaced apart evenly like shown in the picture.

The holes should be just big enough that the rubber will have to stretch to put the white K'nex rods through.

The white K'nex rods should be put through the holes in the rubber just far enough that the hole fits around the indented part of the rod.

I originally also used duct tape for this which worked even worse than the last time I used duct tape in this project.

Step 17: Connecting the Wiper

You may need to adjust the height of the wiper depending on how much drag yours makes depending on its height. too much drag can hinder movement of the floor cleaner.

Step 18: Adding the Sponges to the Sweeper

First use an xacto knife / pocket knife / scissors to cut the sponge down to 2 1/4 inches by 1 1/2. the height is not very important because the sweepers can be adjusted up and down. However they should be tall enough that when they are completed, the white supporting rods will not touch the ground.

Next cut a hole in the center of each sponge.

Turn the whole floor cleaner upside down

Then remove the white rods from the ends of the sweeper arms.

slide the sponges on so that the grey pieces fit in each of the sponges holes.

Put the white rods that you removed earlier back on. These will help hold the sponges in place.

Turn the sweeper right side up again.

Finally Lower the arms that hold the sponges until they touch the floor

Step 19: The Dripping System

Drill a small (as small as you can possibly make it) hole in the bottom of a small plastic tub / bucket. The Bucket I used says that it holds about a liter. The first time I made the hole, it was a little bit to big and water dripped out too quickly, flooding the kitchen. So make sure the hole is very small.

Next cut out a small piece of piping a little more than 7 inches in length.

Finally hot glue it around the hole in the bucket so that when you put water in the bucket, it will drip out of the hole and through the tube.

Step 20: Connect Your Drive and Steering

connect the wires of your drive and steering systems to the corresponding ones on the circuit board that you added wiring terminals to in step 2.

Your wires might not be long enough to reach so you might have to extend them like I did.

When i first tested my floor cleaner it the steering and drive were reversed. If you have this same problem reverse your wiring connections.

Step 21: Install the Dripping System

Hopefully your bucket / tub fits in the frame nicely otherwise you might need to modify the frame a bit so that it will.

Make sure that the tube goes right over the sponges so that when water runs through it will drip on the sponges.

Be sure to check for leaks before you install the drip system.

Step 22: Testing

Now you are ready to test your remote controlled floor cleaner!

Be sure you have batteries installed in both your K'nex motor and RC system.

Turn on the switches to both the RC system and K'nex motor.

Pour warm water into the dripping system with a cup.

Now your ready to clean! be sure to keep driving because water will keep dripping through the dripping system as long as there is water left.

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