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Thread: Minimax MM20 upper bearings

  1. #1
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    Minimax MM20 upper bearings

    My upper wheel bearings sound like they are in need of replacement. Just checking in to see if abyone knows the bearing number? The number is facing in on
    mine. I’d like to get a new set before I pull the wheel off.

    I tried to order through SCM but they sent me guide bearings.....
    Bumbling forward into the unknown.

  2. #2
    My acm saw had the same size sets of bearings on both wheels.
    If it is the same as my saw, then the top wheel shaft is movable in the cast carriage and there is a bolt for adjustment.
    If the saw was running prefect then I would suggest measuring wheel position/protrusion from the cabinet.
    Might be necessary to get wheel plum first, so might be worth measuring the tracking knob distance before you start. if there is a fair of adjustment.

    The top wheel might slide of without pullers, but you may need bearing pullers for removal of the shaft of the lower wheel.
    As again if it was perfect before, If taking off the lower wheel, then leave one of the east or west jacking bolts alone.
    Easier to align the north south ones. take a snap of the position when you remove the bolt and washer.

    You also need some tool for removing the retaining clip, i'm sure you could get one cheap.
    I bought SKF ones for the job, I think it was about 25 quid for the four, but I've recently read that SKF can be a loose fit on shafts, compared to other brands.
    Don't know if that's true or not?
    I heated my bearings, and froze the shafts, two great youtube videos by Jack Forsberg on bearings worth watching.
    I think I used a dowel for knocking the old ones out, but would think there's a much better way to remove them using the pullers and some ingenious way
    of getting a plate inside.
    Eager to see

    Tom

    DSCN2397.jpg
    DSCN2401.jpgDSCN2400.jpg
    Last edited by Tom Trees; 05-06-2021 at 10:27 PM.

  3. #3
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    Thanks, Tom. Appreciate the insights.

    I spoke with Patrick Walsh and he had the bearing numbers. The number is 6207-2RS i
    decided to get the Abec 3 version which is rated for higher stress since I run a carbide blade all the time. The current set lasted about five years, which seems a bit low to me.

    I do have the necessary snap ring pliers and a bearing splitter for pulling the shaft.
    Bumbling forward into the unknown.

  4. #4
    Brian, all good info so far. I will add that pounding the upper wheel back onto the arbor shaft is murder. I used the heaviest dead-blow mallet I own and still had to take a break halfway through. I would coat the arbor shaft with a little grease and also, a dab of anti-seize on the main bolt threads. Hope this helps,

    Erik
    Felder USA Territory Representative: Central & South Texas

  5. #5
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    Quote Originally Posted by Erik Loza View Post
    I will add that pounding the upper wheel back onto the arbor shaft is murder. I used the heaviest dead-blow mallet I own and still had to take a break halfway through.
    Erik
    ...This might explain why woodworkers stay in shape without ever having to go to the gym.

  6. #6
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    Here is my plan so far, please feel free to shoot holes in it.

    planning to remove the shaft support assembly, shown here. Press out the shaft and install new bearings using the hot bearings cold shaft method or a press (or both).

    DE59D830-1BA4-4978-91D7-7329895891AA.jpg
    Bumbling forward into the unknown.

  7. #7
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    Do not heat the bearing over 300F or so. I grind down the outer diameter on the old bearing and use it to press in the new one. You may have to disasemble it in two so only the outer races touch. If you heat it red hot and let it cool the inner race can be drilled out a little bigger and also used to press on the new bearing. You only need to take off 5/1000" or so to get enough clearance.
    Bill D.

  8. #8
    There shouldn't be any need to superheat parts for this project. I've rebuilt many MM's from a bare chassis, up. Maybe put the bearings in a ziploc bag in some hot water but that's it. All things being equal, I would rather have a large puller and mallet than be boiling parts. You can't really hurt anything in this machine. Brian, is that sound deadener in there?

    Erik
    Felder USA Territory Representative: Central & South Texas

  9. #9
    Has getting them out of the wheels been addressed yet?
    I presume there's fancy pullers with exchangeable arms so the ends can get inside the inner race somehow,
    or some expandable round plate to do the job.


    Was thinking it could be done with stacks of shaped sheet metal thin enough to get in there.

    Pity I didn't think ahead and take more notes, I would want to know I done the best job I did now, as there's a slight hint of a thud, when the upper wheel is spun
    without a blade installed.
    Not sure if it always was there, and I can slide my upper wheel off the shaft without all that sweat,
    again not sure if it would have been an easy job with the old bearings. (a few things were a bit ceased when I got my old machine)
    Might have a look at presumably original Koyo's again as there was nothing wrong with them, probably battered now though from my dowel shenanigans.

    Sorry if the above is already sorted,
    Thanks
    Tom
    Last edited by Tom Trees; 05-07-2021 at 10:43 AM.

  10. #10
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    Quote Originally Posted by Erik Loza View Post
    There shouldn't be any need to superheat parts for this project. I've rebuilt many MM's from a bare chassis, up. Maybe put the bearings in a ziploc bag in some hot water but that's it. All things being equal, I would rather have a large puller and mallet than be boiling parts. You can't really hurt anything in this machine. Brian, is that sound deadener in there?

    Erik
    I think I’ll press in the bearings at room temp and install the shaft frozen. Heating a bearing above boiling is poorly advised as Bill mentions, so I don’t do that.

    Anywho, forgive my ignorance since I have not broken down this machine before, but I assume the shaft support can be removed if the spring pressure knob is totally backed off. Is that accurate?

    Very much Appreciate your guidance!

    Tom and Bill, thanks for your thoughts as well.
    Last edited by Brian Holcombe; 05-07-2021 at 11:02 AM.
    Bumbling forward into the unknown.

  11. #11
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    Make sure the new bearing are rubber sealed on both sides.
    Bill D

  12. #12
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    I recommend everyone buy a small bearing splitter say around 2". Buy it used on the bay before you need one and get a good price.
    Bill D

  13. #13
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    I have a bearing splitter, one of the best purchases I made for working on cars. I went totally overboard on snap ring pliers and bought the full lineup of knipex recently after having dealt with one crappy pair or junky adjustables for the last twenty years or so.
    Bumbling forward into the unknown.

  14. #14
    Here is one video of a few on Jacks channel, which demonstrates heating the bearing on a light bulb.
    https://www.youtube.com/watch?v=ocsnUBYEyuM

    I don't recall my bearings being this easy of a fit when I did it.
    https://www.youtube.com/watch?v=Bza0WiKMckE

    Hope to see some clever way to take the bearings out of the wheel, if things are tight.

  15. #15
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    Roger on the bearings, I’m good to go on those. I’m more curious if that whole carrier can come out easily. I’ll find out in a few days I suppose but knowing would help my planning a bit.
    Bumbling forward into the unknown.

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