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Monday, January 21, 2013

Teardown: Roomba wheel assembly taken apart - Hair/debris cleaning - Roomba 760, 770, 780

Today I was preparing my Roomba 780 for it's weekly home-cleaning job... and I noticed that the left wheel was very stiff.
I searched online for some solution, or some disassembling guide.
I found nothing usefull, so I'm going to report here my experience in Roomba wheel assembly dismounting, cleaning from debris/hair, and reassembly.

I suspect this is the kind of issue that precede a broken wheel motor and/or a roomba continuously circling due to a stuck wheel...

So... here we go! :-)

Place your Roomba upside down.
  1. twist off the 4 circled screw
  2. remove the battery cover
  3. remove the battery
  4. remove the brush (and re-twist it's screw to not lose it)
  5. remove the front wheel


Here is our Roomba ready for disassembling.
Gently pull up the bottom plastic cover.

And now we have a bottom-naked roomba.

Here is a detail of the left wheel, the one I need to fix.
Remove the 3 circled screws.
The right screw will come off, the 2 left screws won't come off (on my unit).

Some other image of the still mounted roomba left wheel assembly



After twisting off the 3 screws, you can pull out the wheel assembly.
Here is the, now empty, "slot" of the wheel assembly.

Here are some images of the wheel assembly form different points of view.





Now, let's take it apart.
You should try to unhook the spring before twisting off the 3 circled screws.
I didn't unhook the spring during my disassembly, the hooked spring made the disassembly a little harder.
Pay attention to the spring, it's very strong, and it's hooked to tiny plastic hooks.


Here is the spring, and the 3 screws of the wheel assembly.

Dismantled wheel assembly.
The electrical connector is in the lower part, and it's connected to the motor with some wire.


Here you can see the switch that detect if the roomba is placed on a floor (wheel pushed inside by the roomba weight when on floor) or not (wheel pulled outside by the spring).

Here you can see the wiring from the switch to the connector.
Squared in white, you can see 2 tiny metal pins: they are holding the connector in place.
You should gently push them out with the tip of a tiny screwdriver.
Use the screwdriver even to pull out the wire of the switch.

Here is the lower part of the wheel assembly... naked.

and here is a detail of the part that hold the electrical connector, you can see 2 holes for the 2 pins that hold the connector in place.

And here we have the top part of the assembly, with the dismounted electrical part.

Now here is the tough part.
Disassemble the wheel gear box.

There are 6 screws that hold the gearbox together.
The 4 white circled screw hold the two pieces of the gearbox. These 4 screws were very tight.
The 2 black circled screws keep the electrical motor attached to the gearbox.



But the tough part is not the gearbox, but the pin that hold the grey gearbox to the blue wheel assembly.
This big pin is fitted in the blue plastic, and in fact is the articulated joint that allow the wheel to move up and down.

The only way to push the pin out is by using brute force, a screwdriver and a hammer.
Update: an anonymous commenter suggested that it may be a lot easier to push the pin out in the opposite direction. It's better you try to push the pin on both side, justo to see if there is an easier side. Maybe I hammered the pin out the wrong side :-)

Find a good place, and start hammering the pin out.
Here you can see the pin coming out.
...after some minutes of hammering...

...now I can use the pliers to finish the job.

and here we have it: finally the gearbox is detached from his articulation.

Eureka: dismantled gearbox!


Removed some gears.
And now what?
Well... at this point I've learned that I can't dismantle any further, the wheel and it's gear are firmly locked on their axis.
But at least I can turn the wheel without the fear of breaking the gears :-)

Now that I've ruled out the possibility that there was something wrong in the gearbox... let's try to clean the pin of the wheel.
I've used some paperclips to create some hooks, to take out the debris and the hair.



 
Here you can see a mix of debris and hair... there was a lot of them.

After taking out a lot of debris, the wheel was still very stiff...
The space you have to work with is very small, nothing bigger than 1mm can enter between the wheel and it's case.

So I decided to go for a more radical route :-)
After looking carefully at the wheel, I marked the internal reinforcement ribs, and then...

Pierce all the wheels!



mmmh... let me see...
...I'm still too far from the debris/hair...

...after drilling another hole...

...now I can clearly see the debris!

Some more cutting... and now my roomba have lightened wheels , like a sport car :-)
And using some bended paperclip I can finally clean it for true.

There were A LOT of hair/debris near the axis of the wheel.

After cleaning, it's time to remount everything up.
I've created a long hook for the spring...
...so place the spring...
...and hook it back in place...





Finally, some tape to close the hole of my brand new roomba lightened wheel :-)


Put the wheel assembly back in the roomba and...





...huston, we have a problem!
I wasn't able to reput the wheel articulation pin fully back in place (see the squared pin in the following image)

and the not-in-place pin conflicted with the pin-holder on bottom-cover of the roomba
The Roomba engeneers placed a pin holder on the bottom, like if there was any possibility that the pin could slip out of place by itself... I mean, it took me much effort and many dozens of hammer strokes to push out the pin... in this universe there is no way this pin could slip out by itself :-)

So, let's do some roomba-bottom-cover modding :-)

Before the modding:

After modding with cutter :-)
Nothing will stop me from putting everything back in place :-)

Now my roomba is assembled back together, and is once again going strong! :-)

This Roomba wheel assembly cleaning operations took me between 3 and 4 hours.
Now the wheel is spinning better, it's not as good as the other wheel, but its much better than before cleaning.
Update: after cleaning some rooms with my roomba, now the cleaned wheel spin very well, it seem to be even smoother than the right wheel.
After all this wheel assembly cleaning operation worked exactly as intended :-)


My roomba model is Roomba 780, but from the image I find online it seem that this wheel assembly module is the same on Roomba 500/600/700 series (Roomba 530 555 560 570 580 620,780, 770, 760)
My roomba is about 13 month old, I use it every week in my home, each week it clean about 5 rooms.

As you may guess, I hate poorly documented guide...I believe that if you are going to make a guide/howto about dismount something, having a lot of Hi-reslutions image is going to help a lot.(you can click any image to see it bigger, or you can CTRL-click any image to see it full-res)
Now, anyone can see what it take to dismount a roomba wheel :-)

If you have a stuck roomba wheel, before deciding to trash it, maybe you can simply try to make 1 or 2 hole in it, and try to clean it's axis :-)
If you can turn the wheel by hand, maybe you can even clean the wheel without dismounting it at all (now that I've dismounted it, I know that :-)

I hope this series of image can be useful to the brave that will venture in the roomba wheel assembly dismounting :-)

34 comments:

  1. Thanks! I managed to get enough sheep wool from the rug out of Roomba. He doesn't veer to the side like a drunken driver anymore.

    Just wish I would have found this before I dismantled one if the wheels down to the point of being stuck. If I do have to make a hole in the future, I might try with the dremmel to cut a channel.

    Love that meme, my favorite. If you haven't seen the source: http://hyperboleandahalf.blogspot.com/2010/06/this-is-why-ill-never-be-adult.html

    ReplyDelete
  2. Thanks, very helpful (not needing it yet but with 4 pets in the household I'm sure that day will come...)

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  3. Thanks. This was incredibly well documented and I enjoyed the read but unfortunately it doesn't help me. The cord for my blinds (on French doors so it's pretty long) is wrapped around the wheel axis. Three times. My Roomba is disassembled to the point where the wheel assembly is removed. Maybe I write the company to figure out the wheel disassemy.

    ReplyDelete
    Replies
    1. I'm happy you enjoied the reading :-)
      I hope you find a way to fix yout roomba wheel.

      Delete
    2. well documented, thank you!!

      Delete
  4. Great write up and pictures. With your guide I was able to take my wheel motor apart where I found a broken wire going to the PCB on the motor. It's fixed!
    Another helpful guide was this one: http://www.vic7767.com/how-do-i/

    ReplyDelete
    Replies
    1. That's an interesting guide, thanks for posting the link
      I'm very happy my guide helped you fixing your roomba :-)

      Delete
  5. Thank you very much for investing time taking the photos and explaining everything. Really, really useful!

    ReplyDelete
  6. Wow, can I send my roomba with the stuck wheel to you to repair? Between my old-needs-replaced computer problems, broken clothes washer, and my crippled roomba I'm totally stressed. Also old and have no intuitive sense about how mechanical things work.

    ReplyDelete
    Replies
    1. I am honored by trust you place in me, but I do not do repairs for a fee :-)
      And due to how much does it cost to send and receive package to/from Italy, your best bet is probably to buy a new wheel module from ebay, you can find them for about 30€ (http://www.ebay.it/sch/i.html?_odkw=roomba+wheel+module+780&_nkw=roomba+wheel+770&_sacat=0)
      And then ask help to some friend with some DIY skills :-)

      Delete
  7. This comment has been removed by the author.

    ReplyDelete
    Replies
    1. Yes, thank you! I am having same dog poop problem and had to get this roomba apart in a hurry. Phew! Your wonderful step-by-step help soothe my anxiety so I could deal with this awful problem. Thanks for your help.

      Delete
  8. Thank you so much!! This was extremely helpful!! We have had our roomba for less than a month when it came in contact with some dog poop that we didn't know was in the room and you can imagine the mess we had!! Could not have taken it apart and cleaned it so well without your help!

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    Replies
    1. I am in the middle of the same problem, smeared it all over my bedroom!!!

      Delete
  9. Incredible work and... guide! millions of thanks for sharing!!

    Questions,questions!! How did you know where were the reinforcement ribs?? (I cant' see the internal other side of wheels) Are always six radius, three on circle marks, and three 60º rotated ?? Can I (carefully) drill any of six intermedial space??

    Thanks
    Fernando

    ReplyDelete
    Replies
    1. I'm very happy this post has been useful to you :-)
      About the reinforcement ribs, I guessed their position by looking at the light reflection on the plastic. There are 6 tiny inhomogeneities in the plastic over the reinforcement ribs.

      Delete
  10. I've recently bought a second-hand Roomba 530, which turns out to have a faulty wheel drive motor.

    Following your Guide was very helpful, but I think I've found out why you said

    'But the tough part is not the gearbox, but the pin that hold the grey gearbox to the blue wheel assembly.

    This big pin is fitted in the blue plastic, and in fact is the articulated joint that allow the wheel to move up and down.

    The only way to push the pin out is by using brute force, a screwdriver and a hammer'.

    From your pictues, you pushed (hammered !) the pin from the SMALLER bush side.

    I started from the LARGER bush side (with the reinforcing ribs) and could literally push the pin out completely with a narrow screwdriver and gentle hand pressure only !!!

    I did wonder whether the pin was tapered, but, on checking the fit of both ends of the pin in the various holes, the two in the motor housing were a sliding fit, the narrower bush on the blue housing was a sliding fit; BUT the hole in the LARGER bush in the blue housing was a MUCH tighter fit - but could still be done by hand alone !

    So, if you try pushing the pin OUT from the LARGER bush end; and push the pin IN from the narrower bush end, NO hammering is necessary either way !!!

    ReplyDelete
    Replies
    1. Good to know!
      Maybe I pushed the pin out trough the wrong side :-)
      Thanks for the tips.

      Delete
    2. This

      http://1.bp.blogspot.com/-JiplJuz0ME4/UPrE9wsN3yI/AAAAAAAACfU/fi4MET_nEvc/s640/IMG_8044.jpg

      and subsequent pictures show that to be the case !

      Delete
  11. i had the same problem with the left wheel of my roomba. i followed this guide but didn't completely dissemble the wheel. instead, once the holes were drilled i cleaned out the trappings and sprayed wd40. it seems to work fine.

    ReplyDelete
  12. No drilling required for this fix. The gear does seem to be locked (glued?) onto the axle somehow, but the wheel itself will still slide off. The axle has grooves that grip the metal wheel hub pretty tight. You just need to find a way to support the wheel assembly so that you can tap the end of the axle. I supported mine across the handle hole on a cutting board, which seemed to work pretty good. A few whacks on the axle hub from the wheel side and the wheel should pop off the axle, leaving you free to clean any gunk out from inside the wheel. Happy tinkering! Jim - Toronto, Canada

    ReplyDelete
    Replies
    1. Hi Jim,

      I'm tryinb to "pop off" the wheel like you said but I am not sure if I am hitting at the right place.

      Do I need to hit the axle from the wheel side ?

      Or do I need to hit the axle hub (the metallic round part around the axle on the wheel side) ?

      Thank you !
      William, Québec, Canada

      Delete
    2. I was able to pull out the gear from the axle by bending gently, rotate and repeat. Once the gear is removed you can push the axle from the gear side even it by the looks of it seems as the axle is too thick. About halfway through I pulled the wheel and the wheel still attached to the axle was removed. The wheel seemed very firmly attached to the axle, much tighter than the gear.
      Assembly was easy, put the wheel back and with the wheel side down on a table the gear could be pushed back for a tight fit until the axle doesn't wooble.

      Delete
  13. I also simply drilled the holes and dug the fur monster out of the wheel! Thanks for the help!

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  14. Ciao Massimiliano

    Ho la ruota dx bloccata e ho seguito le tue istruzioni , la ruota adesso senza gli ingranaggi gira bene ma quando rimonto la scatola torna ad essere molto più dura di quella sinistra.
    ho provato ad alimentarla prima di montarla nel roomba e gira senza apperenti problemi ma quando la monto nel roomba non gira.
    Hai qualche suggerimento ?

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    Replies
    1. Ciao,
      Nel mio caso specifico, smontare tutto fino agli ingranaggi è stato inutile, perche a bloccare la ruota era lo sporto dietro alla ruota (e quindi ho fatto il buco per togliere lo sporco).
      Ma la mia ruota era dura allo stesso modo sia da montata, sia con gli ingranaggi smontati.

      Se la tua, invece, gira bene con gli ingranaggi smontati, ma diventa dura quando rimonti gli ingranaggi, all'ora il problema potrebbe essere altrove: quando la hai smontata, ed hai smontato anche gli ingranaggi, prova a girare l'ingranaggio di metallo attaccato al motore, se è duro allora è qualcosa nel motore, ed in questo caso o si vede cosa c'è che non va, oppure è probabile sia da sostituire. (se è colpa del motore, volendo, potresti anche provare a smontarlo... ma se il problema è il motore le possibili cause che mi vengono in mente sono: cuscinetti/boccole rovinate, difficili da trovare/sostituire; oppure spazzole rovinate (sempre che abbia le spazzole) ed anche queste non sono facili da sostituire... se è il motore magari su ebay trovi un motore di ricambio, senza sostituire tutto il blocco ruota/ingranaggi... ma è comunque un'operazione un po a rischio, perchè magari bisogna saldare fili e cose simili)

      Se invece togliendo gli ingranaggi, sia la ruota che il motore girano bene, all'ora deve esserci qualcosa che non va nei singoli ingranaggi: prova a rimontarli uno per volta fino a capire dove sta l'intoppo.

      Delete
  15. I disassembled everything and the wheel and plastic gears spin fine by themselves. However, when I connect the plastic gears back to the metal gear on the motor, there is the same slow spinning resistance I had before taking everything apart. I don't see anything inside the motor (armature) that's obstructing it from spinning faster. Would it be safe to spray WD-40 in there or does this mean I need to buy a new wheel motor / wheel assembly?

    ReplyDelete
    Replies
    1. Sorry, but in my opinion I think that spray WD-40 near electrical parts is NOT safe.

      Delete
  16. Hi, have you ever ran into a situation where it's not the actual drive wheel module? I have purchased a new module and have the same issue. I have also tried taking wheels off a working Roomba and have the same situation where it just spins in a circle. It's like it's not getting the signal to drive either forward or reverse. I completely disassembled the robot and inspected the circuit board for broken solder joints or any hot spots and didn't find anything that stood out. I'm stuck now, not knowing what to do.
    Your help would be greatly appreciated.
    Rob

    ReplyDelete
    Replies
    1. Maybe ther is something broken on the main board...
      here http://www.guerriniinformatica.eu/3-irobot-manuali-tecnici.html I found a link to some service manuals for roomba 400 and 500 series... but I didn't find any service manual for 600/700 series.
      But still, maybe you could fine something useful event in the service manuals of previous generation...

      Delete
  17. i'm getting an error 5 right, spin roomba side wheels to clean. i just bought new ones and put them in and getting the same message. any help would be nice

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  18. It is possible to disassemble the wheel to the very end, so you don't need to drill it. Open vice jaws to a width that will allow for all gear pins to be between jaws, but not wider. Cover vice with cloth. Put the wheel on the vice and tap the pin with 4mm tap and hammer carefully.

    http://glebi.us/tmp/roomba_wheel.jpg

    ReplyDelete
    Replies
    1. Thanks for the information, and for the sample photo.

      Delete