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8" Grinder having problems

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  • 8" Grinder having problems

    Hello guys

    I have a 8-in chi-won grinder that I have been using for sharpening my tool bits. As of recently , I have noticed that the wheels have quite a bit of run out. This grinder is not new, Ive had this thing for about 25 yrs now. Just recently I replaced both wheels, and noticed that the new wheels woobled left to right, and hoped up and down. Thought hmm, I must have gotten what I paid for down at the local Princess Auto.

    I figured I should just replace the wheels, could get lucky and get a truer running set. I pulled the wheels, and put on a set that I had run on this grinder before. I fired it up, and got the same results. I thought OK maybe somthing else is going on here, so I figured I,d best have a look.

    First thing was look at the plastic bushings thats in the centre of the wheels.
    These where pretty loose fit to the shaft, about .015 bigger than the shaft.
    I thought that may be the cause of the wheel hopping, but shoun,t have anything to do with the side to side wooble. I started looking for other things that had a loose fit, and found the washers , probly not the correct name, had a loose fit on the shafts as well. The shaft also shows a slight groove a few thou deep on the inboard side, this is where the washer sits against the shoulder. The out board sides show no marks or wear. Kinda strange, but none the less , they are there.

    First thing I thought was to machine bushings to fit the bore of the wheels, and get rid of most of the .015 play that exists now with the plastic bushings.
    I wonder if its safe to do this, or is the plastic bushing in there for a purpose that I,m not aware of?

    The next thing I was thinking, was to make up a new set of washers. I don,t know if they can be damaged from possibly over tightning, or not. I see that there is signs of wear on the washer, where it butts up against the shoulder on the shaft. Could this be the source of the wobble? These washers look to me as they are just stamped out , and not a machined peice.

    This leads to the next question. Again, is it safe to machine my own, or are the stamped out stockers done this way for other reasons? One last thought was to machine up new inboard washers, with the bushing as one part.
    I would think in doing it this way , the inboard side washer / bushing as a assembly would have to run much truer than being seperate items.

    I could be way off base here guys, and would really like to hear your thoughts on this. And yes the bearings on the grinder seem ok, and the shaft has no play that I can feel.

    Cheers Paul

  • #2
    I'd make a new set of washers (machined) and a new PLASTIC bushing with
    a few thou of clearance so thermal expansion dosent cause a disaster. On the
    washers don't forget to relieve the inner part and be sure the "blotter" washers
    are on the wheels.


    • #3
      I would absolutely turn up sets of drive plates-washers. I'd probably use 2"
      12L14, if I've got some around. If you don't want to make new plastic bushings, use a couple wraps of making tape around the spindle instead. It's not loaded once the nuts are tightened. Finally...

      Get a dresser so you can make the wheels round. The little diamond bar deals, even the cheap ones, work fine for occasional use.
      "Lay on ground-light fuse-get away"


      • #4
        8" Grinder having problems

        Thanks for the input guys

        I was at the local Princess Auto last night , and while cruising towards the check out I noticed they had the 8-inch bench grinders on sale for a whole 44.00 bucks. I thought OK lets have a look. The new one looked to be a tad smaller than my old grinder,but was still 1/2 hp as my old one is. So, I figured for that price what the hell, P/A has a great return policy, and if I didn,t like it, just return it.

        As it goes, the grinder runs super smooth, with wheels installed, witch kind of shocked me. This new grinder allso runs really quiet compared to the old one.
        The rests are made paper thin, but thats OK , my old ones bolted rite on.
        The wheel guards where also much thinner material, but hey, they will serve the purpose.

        How long will this thing last,,,,,,,only time will tell.
        I purchased the old one 25 yrs ago, and didn,t think it would last a yr, but it
        has. I just couldn,t see spending my time making up washers and bushings for the old grinder. I have enough projects on the go now to be waisting time on that.

        I was just about to cart the old grinder out to the trash bin, and the wifey says hey, don,t do that. I said what, I don,t need this one any more.
        She says, I,ll pick up a few of those polishing wheels and she can still use it for buffing up aluminum parts. Thought OK, the old grinder will still has a purpose, and it,s saved from the trash bin.

        Cheers Paul


        • #5
          Paul-- don't toss the old grinder because of loose bushings. Likely if you tightened up the wheel bushings, you would have no problem with the old, high-tolerance washers. If you think about it, the bushing is what is responsible for getting the wheel square to the shaft. The slop in the old washers is probably there so they don' t have so much influence on the wheel. If the washer was out of square between its cup edge and the part that abuts the shoulder on the grinder shaft, then they could indeed cause wobble. A gentle truing pass on the existing washers, on the lathe would take care of that.

          Paul Carpenter
          Paul Carpenter
          Mapleton, IL