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Thread: Hitachi M12 Bearing Replacement

  1. #1
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    Hitachi M12 Bearing Replacement

    ****Just a note, the various router out there will have different methods of disassembly and reassembly. My hope here is to show you that for a small replacement cost of bearing (Buy them from a bearing supply house NOT the tool maker!!) your router can be good as new!****

    Well the time had come, my Hitachi M12 router, the one that lives in my router table, needed new bearings, I figured I'd better do it before I accidentally let that factory installed smoke out of the motor

    The last few times I used it, I noticed a lot of vibration, and a not so nice cut

    I ordered the bearings, NTN Japan made, 6200ZZ and 6201ZZ, they came overnight (got to love that Monotaro.com place ) and cost me a grand total of................ about $3

    OK, I took the router off the table, I left the plunge base attached to the rounter plate, no need to mess with that. I first removed the brush cups, and the brushes

    Attachment 6889
    Unfortunately one of the cups was cracked, this router I bought used, and it had seen some hard use, but the look of things.....

    I also found one brush was slightly chipped.

    Attachment 6890
    I managed to super glue the cup together and will use the chipped brush until a new one arrives, as well as the cup.

    I then removed the 4 large screws holding the plastic body to the aluminum base, and removed the armature and aluminum base as one unit.

    I then lightly clamped the armature in the vice (with wood between the vice and the armature, and I mean LIGHTLY clamped it) and removed the collet from the end of the armature shaft.

    I could then lightly tap on the end of the armature shaft with a plastic hammer to remove the armature from the bearing that lives in the aluminum housing at the bottom of the router.

    Now to remove the bottom bearing from the aluminum housing........

    Attachment 6891
    There is a small triangular plate that holds the bearing in place, remove that.......

    Attachment 6894
    ........and you can see the bearing.

    You could just bang it out, but you could also bust the aluminum housing, so I decided to press mine out with my wood vice.....

    Attachment 6892
    A couple of pieces of plywood to keep things in line and apply pressure on the right place.............

    Attachment 6893
    .......and I have the bottom bearing out of the router!!!

    Now forgive me, but I forgot to take pics of the top bearing being removed, I used a two legged gear puller and just pulled it off, not much to see....

    With both bearings off the router, I can take a look.....

    Attachment 6895
    Both bearings had been apart at some point as you can see by the damage done to them, the seals were removed and maybe some grease was added, I do not know, but for the price of bearings............

    So, I now have both bearings out, and I can start replacing them with new ones......
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  2. #2
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    OK, on to the replacement of the bearings.

    I put the bottom bearing in first, you have to make sure that the area the bearing is going is clean........

    Attachment 6896
    ......I used my one of my socket that was just about exactly the same size as the outside of the bearing, then just carefully tapped the bearing in place, then put the triangular metal plate back on, with the three screws.

    Next, I'll put the to bearing on to the armature. I put a socket over the other end of the armature shaft, so the threads on it do not get damaged......

    Attachment 6897

    Attachment 6898

    I put that end on the bench, and proceed to put the top bearing on the armature.

    Again, I use a socket to drive the bearing onto the armature shaft, I get one that is just the right size......

    Attachment 6899

    ........and then carefully tap the bearing on, keeping it straight and level.....

    Attachment 6900

    (the hammer is a little oversized, you really only need to tap on the bearings to get them on).

    Attachment 6901
    There, the top bearing is in place.

    Now, at this point, I find it easier to temporarily put the armature into the plastic housing, I find it holds everything in place better..........

    Attachment 6902
    Again, a socket is used to tap on the solid part of the armature shaft, without damaging anything.

    Attachment 6903
    Once the armature is in place, I place the aluminum housing that holds the bottom bearing over the armature, and again a socket is used to tap on the bearing, avoiding damage.

    ** You always want to tap a bearing race (they have two, and inner and outer) that is next to the shaft, or housing that the bearing is going onto.**

    Once tapped in place, I need to put the collet back on the end of the armature.

    Attachment 6904
    I remove the armature from the plastic housing, and again LIGHTLY clamp it in the vice, and install the collet. The collet does NOT have to be cracked down, as the spinning of the router will make the collet self tighten, it should be "Snug".

    Now I put the 4 large screws that hold the plastic housing to the aluminum housing and tighten them down. Next, the brushes are put back in, and the cups to hold them in place, all that is left is to put the router back on the plunge base, and fire it up!!

    Hope this helps someone, took me less than a hour, the only "Special" tool used was a gear puller................


    Like this one. Mine cost me about $12, and I've used it at least a dozen times.

    One hours work, $3 in parts, and my router is just about as good as new, it sure cuts smoother now too!!

    Cheers!
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  3. #3
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    Hey Stue, very interesting.

    I didnt see how you used the gear puller. What did you use it on?

  4. #4
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    Thanks Julio

    I used the gear puller on the bearing at the top of the armature near the brushes, just popped right off.

    Cheers!
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  5. #5
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    oops now I see where you mention it, guess I'm guilty of looking at the pictures and not reading,

  6. #6
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    Good job, Stu

    Have you ever thought of adding a varible speed control unit to your table? Any problems with just the single speed?

  7. #7
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    Ya mean like this one...........


    Yeah, this one actually blew up on my, I bought one local, and it has been fine.

    Cheers!
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  8. #8
    Hey Stu came across this thread. Thanks very much.
    Could i worry you for the size of that gear puller?
    Also is there an equivalent site in english to order the bearings?
    much appreciate the help
    Ant

  9. #9
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    Nov 2006
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    Zushi, Japan
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    Great one Stu. Like I always say a little maintenance goes a long way. Long live your Hitachi.

  10. #10
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    Quote Originally Posted by Anthony Jordan View Post
    Hey Stu came across this thread. Thanks very much.
    Could i worry you for the size of that gear puller?
    Also is there an equivalent site in english to order the bearings?
    much appreciate the help
    Ant
    Anthony, the gear puller is about a 4" unit....? I'd have to go look to find out exactly, but I have three gear pullers, it is the middle sized one. There are lots of places online that sell just bearings, Google it and I'm sure you will find something in your area.

    Cheers!
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

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