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Two ways to balance a grinding wheel

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  • Two ways to balance a grinding wheel

    Over the years I've seen several articles that present solutions to the problem of how to balance a grinding wheel on a bench grinder. I ran into this problem recently and found a couple of solutions. See what you think. - metalmagpie

    http://www.nwnative.us/Grant/shop%20...able/balancing

  • #2
    Great job and I'm going to make some washers as well I think.

    Why didn't you mount your cell phone on there and quantify the results .

    Thanks for posting - so many people use bench grinders and pull their hair out trying to balance it and then move to using belt sanders. I was in the same boat until my bench grinder was balanced. I use my bench grinder a lot more now.
    www.thecogwheel.net

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    • #3
      Since I didn't see mention of it, did you dress the wheels before balancing? In theory, that should at least make them concentric with the center hole.

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      • #4
        It is interesting how little weight at a small distance from the center of rotation will balance these wheels.

        Thanks for the education.
        I hear and I forget.
        I see and I remember.
        I do and I understand.
        Confucius (孔夫子)

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        • #5
          Originally posted by DR View Post
          Since I didn't see mention of it, did you dress the wheels before balancing? In theory, that should at least make them concentric with the center hole.
          I did true the blue CGW wheel before balancing. It was the one that had the most imbalance. Dressing it true didn't help the balance that I could detect.

          metalmagpie

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          • #6
            Originally posted by enginuity View Post
            Why didn't you mount your cell phone on there and quantify the results .
            I did install Accelerometer Meter on my Android phone. I tried just holding it against the grinder body. I got readings, but at the time didn't really understand what I was seeing. The metric I was interested in optimizing was the finish on the drills and lathe tools I ground anyway. I like numbers and might go back and measure some data someday. But you can just as easily put a tuna can full of water on the grinder table and look at the pattern on its surface. That's a pretty revealing test, actually.

            metalmagpie

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            • #7
              Originally posted by DR View Post
              Since I didn't see mention of it, did you dress the wheels before balancing? In theory, that should at least make them concentric with the center hole.
              Maybe.

              Wheels need a little clearance around the hub, both so they can slide on, and so they are not being forced and stressed radially. That means they can be mounted slightly off-center, and that also the balance can therefore be different on the grinder from on the balancer, unless you have a tapered hub that stays on the wheel and mounts consistently on the spindle.

              Dressing SHOULD just remove material of even density all around. If so it won't change the balance of a previously balanced wheel that has not been re-mounted. But if balanced in one position vs center, then re-mounted and dressed, the previous balance may not be valid, and removed material may not result in a concentric surface, changing the basic balance of the wheel.

              How much effect there can be from the mounting depends on how much clearance there is from wheel to hub, and hub to spindle.
              CNC machines only go through the motions.

              Ideas expressed may be mine, or from anyone else in the universe.
              Not responsible for clerical errors. Or those made by lay people either.
              Number formats and units may be chosen at random depending on what day it is.
              I reserve the right to use a number system with any integer base without prior notice.
              Generalizations are understood to be "often" true, but not true in every case.

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              • #8
                For safety shouldn't you put a larger washer with relieved center against the wheel, and put the teardrop washers outboard of that?
                Jim

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                • #9
                  Originally posted by J Harp View Post
                  For safety shouldn't you put a larger washer with relieved center against the wheel, and put the teardrop washers outboard of that?
                  Likely so.....
                  CNC machines only go through the motions.

                  Ideas expressed may be mine, or from anyone else in the universe.
                  Not responsible for clerical errors. Or those made by lay people either.
                  Number formats and units may be chosen at random depending on what day it is.
                  I reserve the right to use a number system with any integer base without prior notice.
                  Generalizations are understood to be "often" true, but not true in every case.

                  Comment


                  • #10
                    Mag, That is a good read and thank you for taking the time to present.

                    I have a question, on a standard bench grinder with two wheels,

                    If you install the self balancing washer on one wheel will this correct the balance of the whole system?
                    "...do you not think you have enough machines?"

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                    • #11
                      No, because the two wheels, even if static balanced at one end, may still have different imbalances. They ADD UP TO what you correct with at one end, but the one at the far end still has a vibration that tends to make that end rotate off-center even of the first end were correct, which it won;t be. The end with the balance weight will be overbalanced, the end without underbalanced.
                      CNC machines only go through the motions.

                      Ideas expressed may be mine, or from anyone else in the universe.
                      Not responsible for clerical errors. Or those made by lay people either.
                      Number formats and units may be chosen at random depending on what day it is.
                      I reserve the right to use a number system with any integer base without prior notice.
                      Generalizations are understood to be "often" true, but not true in every case.

                      Comment


                      • #12
                        Originally posted by metalmagpie View Post
                        Over the years I've seen several articles that present solutions to the problem of how to balance a grinding wheel on a bench grinder. I ran into this problem recently and found a couple of solutions. See what you think. - metalmagpie

                        http://www.nwnative.us/Grant/shop%20...able/balancing
                        I see says the idea came from a thread i posted in 2005 (he gives the link).

                        Learned a thing or two since then. While the idea works, 11 years later i'd reflect that it, and what he's doing is just over complicating things, esp for a bench grinder. Instead, with a balancing rig, just rub off a bit the grinding wheel material on the side corner with a carborumdum dressing stick. Gets the same result, easy and fast.

                        Grinding wheels have some clearance on the shaft both for installation and for safety. The rotor (and therefor shaft) is going to warm faster than the wheel and radial pressure in the ID of the wheel from an expanding shaft is to be avoided.

                        semi ot; Surface grinders avoid this with wheel hubs. You leave on the wheel and have a taper mount system for fixing them to the shaft. (but you still want a soft start/stop because the jerk on starting can shift the wheel slightly undoing all the careful balancing). There's a crowd that will say you don't need to balance surface grinding wheels; these people see the world through their commercial experience and within that they're right....however on light grinders likely to be seen in the home the perfect finish is slightly elusive and balanced wheels make a difference.

                        So, neither static balancing or dressing will not get it dead on because of clearance....for that you'd need dynamic balancing. However, I wouldn't bother. Static balancing and dressing will go a long way towards solving most of the problem....and after all, its bench grinder.
                        Last edited by Mcgyver; 07-28-2016, 09:59 AM.
                        in Toronto Ontario - where are you?

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                        • #13
                          They have a pretty goot lever arm from wheel to wheel, so trying to balance both from one end sounds like a bad idea... the thing will try to walk away if the balance isn't at least decent at each wheel. Static balance will be fine at each, but naturally best if it can be done with the wheel on the grinder. Usually that is not possible due to friction, so you end up static balancing the wheel e;elsewhere and hoping it's OK, which it often will be..
                          CNC machines only go through the motions.

                          Ideas expressed may be mine, or from anyone else in the universe.
                          Not responsible for clerical errors. Or those made by lay people either.
                          Number formats and units may be chosen at random depending on what day it is.
                          I reserve the right to use a number system with any integer base without prior notice.
                          Generalizations are understood to be "often" true, but not true in every case.

                          Comment


                          • #14
                            Very interesting read. I learn every day.
                            Paul A.
                            SE Texas

                            And if you look REAL close at an analog signal,
                            You will find that it has discrete steps.

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                            • #15
                              Originally posted by Mcgyver View Post

                              So, neither static balancing or dressing will not get it dead on because of clearance....for that you'd need dynamic balancing. However, I wouldn't bother. Static balancing and dressing will go a long way towards solving most of the problem....and after all, its bench grinder.
                              I agree that static balancing works - I statically balance the wheels I use on the surface grinder at work once they are mounted on the hub. The bench grinder I find to be a bit more involved in that you need to mount the wheels on some sort of arbor and statically balance the wheel itself and then move it to the bench grinder - which leaves a lot of room for error. I think if you had a high quality bench grinder it would be pretty close once you dressed it. Statically balancing while the wheels are mounted on the grinder is hopeless.

                              I have an import bench grinder from Home Depot. I think (now at this point I'm hypothesizing - I haven't actually checked) that there is much to be desired in out of the box state of many import bench grinders. I really don't think the manufactures balances them. This I think is the problem with a lot of bench grinders. Yes the wheel can be out of balance, but so too can the grinder itself. The reason nobody cares is because most bench grinders are purchased to mount a wire wheel on one side and sharpen law mower blades on the other. Only the machinists and elite woodworkers want a really nicely balanced setup.
                              www.thecogwheel.net

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