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  • Surface Grinding Wheels

    I recently purchased a 7", 3/4 hp surface grinder for home shop use. Based on advice from this forum, I also purchased four additional wheel hubs in order to mount a selection of wheels. I have no experience or training in surface grinding. Grinding will be primarily on small, mild steel pieces, but may include HSS, aluminum (6061), grey cast iron and brass. I don't expect mirror finishes will be required.

    Ignoring the fact the unit comes with one wheel, what four wheels would make up a versatile selection for my home shop use??

    Fred

  • #2
    What Grinder followed You home? I know You've been looking for one for a while.
    All I have is white Norton wheels, general purpose. I've never ground alum. or brass, but I have ground rubber.
    Post a pic or two Fred, You know the drill .

    Steve

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    • #3
      For hardened steels, Norton 38A, 46 or 60 grit,h hardness
      for mild steels Norton 32A, 46 or 60 grit, j hardness
      for the nonferrous. Norton 86C 46 or 60 grit, j or k hardness
      Maybe a Diamond wheel for tungsten carbide?
      Better yet, Let Evan guide you. His wife is in the biz. Maybe SGs would be more versatile.

      Comment


      • #4
        Fred, hope you don't mind my butting in with a question.

        Been wanting a SG for years, just bought one a week ago, not able to get it picked up as yet, anxious to get it here, up and running. A manual B&S No.2 6x18

        My question, there is a like new diamond wheel on it but some one had gouged a perpendicular slot across the face about 1/8" wide with a fixture that was on it.

        Is the wheel still usable or just cause for problems?

        Comment


        • #5
          Fred, I don't know what grinder you got but I think you will find that just changing the wheel and not the hub will be the best and fastest. First you don't have to balance the 7"" wheels used on the small surface grinders and second you will get tired of pulling the wheel mounting hubs off the spindle and it's completely unnecessary to do that.

          In all the shops I worked that had the 6x12 surface grinders none of the balanced the wheels or removed the mounting hub unless something was wrong with the machine.

          You don't balance your bench grinder wheels do you? Then why do you think you have to balance the 7" surface grinder wheels?
          It's only ink and paper

          Comment


          • #6
            Who said anything about balancing?

            Comment


            • #7
              Grinding

              I agree with Carld. You don't to balence a 7" wheel just dress it.
              A rule of thumb as far as your bond. Hard material use a soft wheel. Softer material use a hard wheel.
              Visit my site for machinist videos free charts & more

              Machinist Classifieds Free Listing

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              • #8
                If a wheel is out of balance it is defective. It does happen but not often with a brand name wheel. I happen to be checking one out right now that costs $1700 which the customer claims is out of balance. It isn't but I haven't done a close check yet for out of round. I will post a pic of it later.


                You have several choices to make. Hard or soft, coarse or fine and what type of grit. Soft wheels cut faster and cooler but wear out faster and don't hold dimension as well. Hard wheels cut slower and hotter but hold dimension much longer. Incidentally, a soft wheel is made that way by including friable non-grit additives such as silica micro balloons or clay particles. These break down easily and release worn grit to expose fresh grit which makes the wheel cut fast.

                Coarse or fine grit also has similar properties to soft/hard except for the resulting finish. Coarse cuts fast and cool and fine is slow and hot. A soft and coarse wheel will remove material at an amazing rate but the wheel won't last long. That isn't as important in industry if stock removal is more important than wheel cost. Time is money. The HSM is probably better off to buy a harder wheel that will last a long time. If you can't afford a selection of grits then a medium grit is the usual compromise, around 60 to 80 grit.

                For the hard materials a CBN wheel for steels and a diamond wheel for carbides are indispensable. A good electroplate diamond wheel will last a long time as long as it isn't abused by grinding steel. CBN wheels will last even longer than diamond and have the advantage of holding dimension extremely well. They cost but good tools always do. Never grind carbide with CBN. It will glaze the wheel and then you have to dress it and waste a lot of expensive grit.

                I use my milling machine as a surface grinder from time to time and I use aluminum oxide jockey wheels for mild steel. Those are cup wheels and they hold up well since they wear across the entire face. And yes, it is a major cleanup job after grinding something but at least the round rod ways are easy to replace if needed. Loosen two sets screws and pull the shaft out.
                Free software for calculating bolt circles and similar: Click Here

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                • #9
                  Ken if there is significant thickness of the diamond layer below the scratch it could be saved . It could be ground down with a coarse vitrified wheel but wheel wear will be bad .

                  Comment


                  • #10
                    Thanks TD, as I recall it was pretty deep, unfortunate, while diamond wheels are not as expensive as they used to be they are still not cheap, undoubtedly done by someone cranking the wheel while looking at the grinder. Maybe it's salvageable for some limited use. I have an old Belsaw carbide circular saw sharpener that has one on it that is used for sharping carbide cutters.

                    Comment


                    • #11
                      I have an assortment of wheels in my shop. Ever since I bought a Triupmh ruby wheel in 60 grit I haven't used any of my other wheels. The ruby is by far the best I have ever used. They generate less heat and require much less dressing. The only thing is they aren't available in all the grits and hardness as the white wheels are.

                      JL.........

                      Comment


                      • #12
                        The ruby grit wheel is a white aluminum oxide wheel dyed red. The colours are not important but the specific formulation of grit and friable materials is. You have found a wheel that is well suited to your use. Real rubys BTW are made of.... aluminum oxide.
                        Free software for calculating bolt circles and similar: Click Here

                        Comment


                        • #13
                          Thanks for the info Evan. I wasn't aware that the ruby wheel is actually a colored ALOX wheel. All I know is I can grind all day long and only have to dress a couple times. They almost seem non consumable.

                          JL..................

                          Comment


                          • #14
                            A Message to the Forum Administrator

                            Hey! How about a little more time for your keyboard challenged participants before you dump the reply editor???

                            Timeouts of the message editor have lost me three hard fought would be message postings in the past two weeks. My two fingers just don't type that fast and I'm too lazy to pre-type my message on another application and/or do frequent copy commands......

                            Fred

                            Edit: Posted in this thread by mistake and under duress (as proven by my message content!!!)

                            Comment


                            • #15
                              Originally posted by Pherdie
                              I recently purchased a 7", 3/4 hp surface grinder for home shop use. Based on advice from this forum, I also purchased four additional wheel hubs in order to mount a selection of wheels. I have no experience or training in surface grinding. Grinding will be primarily on small, mild steel pieces, but may include HSS, aluminum (6061), grey cast iron and brass. I don't expect mirror finishes will be required.

                              Ignoring the fact the unit comes with one wheel, what four wheels would make up a versatile selection for my home shop use??

                              Fred
                              I am assuming you got the HF surface grinder like the one I purchased.

                              I also ordered extra hubs for my grinder and I did a little research on wheels. My first attempt grinding was to use the white ALOX 60K wheel that came with the grinder. It actually worked better than I expected. But, I thought I could do better. My first wheel purchase was two 32A wheels based on a brochure I found on Norton's site that suggested that a 60K or 80K wheel would be appropriate for grinding mild low carbon steel. My experience was that these were not ideal wheels for getting the best finish on this type of material. They were too hard and tended to chatter no matter what I did. I then tried white Alox wheels purchased from Enco, both 46j and 60i grade, that seem to do a better job on the 1018 and cast iron that I was attempting to grind. The fact is it is more difficult to grind low carbon steel. I had better luck grinding H13 and some unknown alloy steel.

                              Then I read the chapter in James Harvey's book Machine Tool Trade Secrets in which he suggests using a softer porous wheel even for materials like low carbon steel. I tried this 46J pink porous wheel from Enco:
                              http://www.use-enco.com/CGI/INSRIT?P...AKA=SZ422-0187
                              This worked better. I have also tried a Camel AZ wheel (blue) with some success.

                              But, I can tell you this: it takes some practice to learn how to grind. It takes some experimenting with technique and with the proper selection of wheels.

                              As to balancing wheels, I note that a number of users say it is not really necessary...if you buy premium wheels. That may be the case, I have not been purchasing Norton SG $70 grinding wheels. There is one way to judge how much of a difference it makes to balance your wheels. Put a dial indicator on the top of the column so you can accurately measure not only the Z axis (I realize there has been some discussion on the issue recently as to which is the Z axis, I mean the up an down axis of the spindle), but also how much vibration there is with the wheel and hub mounted. My experience has been that without a wheel mounted on the grinder and using a .0001" DI I observe no movement in the DI needle. It runs very smoothly as expected. If I mount the wheel and run the grinder without dressing the wheel you can definitely see the DI needle wobbling. Dressing the wheel makes a difference. Balancing the wheel and dressing it together usually allows the grinder to run as smoothly as if there was no wheel and hub on the machine. Yes, the wheel does make a difference. I received one wheel from Enco that I just could not get to balance. It was just too far off. But, of the other six wheels I have received (USA and imported) all were improved by balancing them. It did not matter which hub the wheel was mounted on, all of them were off to some degree. Would it matter if the grinder weighed 1500lbs instead on 450lbs? Probably. How much does all of this make in the final grind? Well, I figure it certainly doesn't hurt to reduce any factor that causes vibration. There are a number of references I found concerning balancing. The best description is in the book:
                              The Grinding Wheel by Kenneth B. Lewis Chapter 12 on truing, dressing and balancing. I built the balancer that was described in the article in HSM last year with modificatons. Works well.

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