How to Clean the Front Wheel of a Roomba Discovery

The front wheels of Roomba Discoveries collect hair and eventually stop turning. This undoubtedly affects performance, particularly cleaning time before recharge, but more importantly, it really bothers me when a robot isn't working at its peak.

Here, I show how to remove and clean the front wheel. This is a surprisingly complex task and will take some time. My Roomba sat on the kitchen counter for a few days as I devoted half an hour here and there to figuring it out. If you are lucky, it is possible to accomplish this without removing Roomba's cover; I was not lucky and had to remove the top cover and bumper. If you're not prepared to spend some time, and potentially remove Roomba's covers, don't start.

I probably sent more time on this project than I would have spent sweeping the floors for the next year. But, that's not the point, is it? I'll watch Roomba work for nearly as long as it would take me to do the same job. I've seen other people do this too, so I know I'm not alone. Cleaning, servicing, and ensuring perfect operation of a Roomba is a way to constructively harness obsessive compulsive behavior.

Step 1: Turn Roomba on Its Back; Figure Out How It Pees

If you're mammalian like me, after a few months of Roomba cleaning your room, its front wheel will be clogged with hair. You can try cutting and pulling the hair out, but save your self some frustration, and go get your tools.

Jeweler's screwdrivers
small needle-nose pilers
a clamp, such as a quick-clamp

Step 2: Expose the Inner Working of the Front Wheel

Remove the front wheel's screw and slide down the metal cover.

Inside you'll find an eccentric press-fit onto the front wheel shaft. This eccentric opens and closes a small switch held in place by the metal cover. Presumably, the motion of this switch lets Roomba know its front wheel is rotating properly. Why isn't there a special 22-note trouble song alerting us to a clogged front wheel? Oh yeah, because cleaning the front wheel isn't a user-serviceable operation, and you've already voided your warranty, violated your service contract, and there are some guys on their way to break your kneecaps right now because you removed that screw and peaked under Roomba's skirt.

Step 3: Pull the Axle Out

The axle is press fit into the front wheel. Find something of approximately the same diameter, and push the axle all the way through the wheel.

I used one of my jeweler's screwdrivers. Probably not the best choice, but what the heck. I was afraid the screwdriver was going to slip and pierce through my knuckle if I pressed with my hands (speaking from experience...), so I used a quick-clamp and a AA battery to jury-rig a press.

Step 4: Look at All That Hair!

Yum.

Save some for genetic analysis if there's any contention in your household as to whose hair clogs the robots.

Step 5: Shove the Axle Back in the Wheel

Put the eccentric back on the end of the axle, and press the axle back into the wheel. Again, I used a quick-clamp as a press (but no screwdriver or battery). Once the axle is through the wheel, align it with the hole on the non-eccentric arm and carefully continue pressing it through.

Step 6: Reposition the Switch and Replace the Metal Cover, If You Can

The switch is held in place by two bosses: One between the switch and the front wheel arm, and one on the switch that sticks into the metal cover. Reposition the switch on the first boss, and spin the front wheel to see the switch in action, turning on an off endlessly as Roomba works so hard. Slide the metal cover down and back into position. You will likely need to press the cover in towards the wheel as it's a tight fit around all that white tape, which presumably keeps dust out of the switch and eccentric.

Here's the tough part. Further up in the channel formed between the metal cover and the wheel arm, there's a plastic guide/bearing. This guide/bearing has a hole that the screw you've removed goes through to hold in place. My fingers, although slender, long, and near perfect in every way, were too fat to fit between Roobma's bumper and Roomba's body to hold this guide/bearing in place from the top of the front wheel assembly as I put the screw back in. Upon disassembly, I realized the wires from the front sensor were also getting in the way.

It is possible to put the screw back and miss the guide/bearing completely. Once you tighten down the screw, you'll realize something is wrong when Roomb'a front wheel no longer goes all the way up.

Roomba, does your front wheel go all the way up?

If the answer is yes, you can see the switch's boss in the smaller hole in the metal cover, and the wheel turns, power on Roomba to see if it's happy. If so, congratulations! Savor the time you've saved by watching Roomba spend 20 minutes cleaning up some crumbs you could have swept up in one.

If Roomba's wheel is fussy, and doesn't go all the way up, carry on.

Step 7: Put Roomba Under the Screwdriver; Ask Friends and Family to Wait Patiently in the Waiting Room

You'll need to remove both the cover and the bumper to get access to the top of the wheel assembly.

I got some direction here from Accessing Disco's Interior, but it's really not that hard. Remove the screws marked, disconnect the cables, and carefully work the cover and bumper back and forth until you can free them.

Start by turning Roomba on its back and removing the battery, dust bin, and brush assembly.

If you're wondering why you got into this situation, and maybe you should have just left things alone, and maybe it would be easier to just try to get another Roomba for cheap, have a significant other mock you and suggest that you're not a real engineer if you can't fix a stupid robot that vacuums the floor. Good, now you're motivated!

Step 8: Remove a Bunch of Screws; Try Not to Lose Them

Remove the screws marked, keep track of where they came from. You can put the screw into ice cube trays like here, or just sit them on the counter with post-it notes. Explain loudly to everyone around how you know you should put the screws in ice cube trays, but you're too lazy, and they should be really careful not to knock the screws on the ground. This is especially true because it's the kitchen counter you're working on.

My Roomba is a model 4210; yours will undoubtedly be different.

Step 9: Free the Bumper

The front bumper has a cable that is attached on the inside center. Separate it from its receptacle with a pair of small needle nose pilers. Next, separate the inside and outside sections of the bumper by starting at each side and prying them apart. The 4210 model has its handle on the bumper, so to actually remove the bumper, you'll need to pull up on the main cover just a little. With the main cover lose, place Roomba on it's wheels and carefully work the bump up and away.

Step 10: Now You Can See the Problem

Arrange the wire out of the way, and position the guide/bearing flush with the top of the metal cover. In this position, the front wheel screw will go through a hole in the guide/bearing and hold it.

So easy with the bumper off, huh? If only I could get my fingers in there without taking the bumper off.

Step 11: Take Off the Top Cover - Roomba, Where's Your Brain?

You know you can't resist, so go ahead and take the top cover off. Careful though, there's another set of wires that need to be disconnected from the top cover before it can be removed.

What's inside a Roomba anyway? My investigations determine that there is dust inside a Roomba.

When you have trouble getting the top cover back on, pop off the data connector cover and ensure that is is aligned.

Step 12: Reassemble and Test

Replace the top cover and bumper making sure to reconnect both sets of wires. To get the bumper to properly mate, you'll have to jiggle the top cover and carefully shove the bumper. Replace all the screws and send Roomba out for a test clean.

Celebrate your fully functioning robot, and appreciate the several months of operation until the front wheel fills back up with hair!