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  • Diamond grinding wheel cup.

    I would like to have better ability to grind carbide using a cup wheel. I would like to buy it from banggood or similar online china purchase store. What type of cup wheel is suitable for sharpening carbide. ?I have a green wheel but truthfully its difficult to use.
    What size and grit is recommended.
    Is this a good purchase.
    https://www.banggood.com/100mm-Diamo...r_warehouse=CN

  • #2
    Being a import, it is of course metric. Can you use/adapt the metric hole size?

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    • #3
      Green wheels are worthless for carbide even though I've them as advertised for that purpose. I've tried it in the past. It's like 70 / 30 meaning 70% of the wheel disintegrates as 30% of the carbide might be poorly ground.
      As far as the diamond cup wheels, it's best to have two grits, one for roughing if needed and one for finishing. I have a 60 gt and a 100 which have worked well for my carbide grinding.

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

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      • #4
        Originally posted by JoeLee View Post
        Green wheels are worthless for carbide even though I've them as advertised for that purpose. I've tried it in the past. It's like 70 / 30 meaning 70% of the wheel disintegrates as 30% of the carbide might be poorly ground.
        As far as the diamond cup wheels, it's best to have two grits, one for roughing if needed and one for finishing. I have a 60 gt and a 100 which have worked well for my carbide grinding.

        JL................
        Strange, I've been using a green wheel for carbide for 30 years, and no one ever told me it didn't work----
        'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

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        • #5
          Green silicon carbide wheels "work," but not very well compared to diamond wheels. Pretty much night and day difference. There's no way to tell which Chinese wheels will be good and which won't without trusting reviews. I have had better luck with the Russian or Ukrainian diamond wheels, which can be had on eBay.

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          • #6
            When we ground Carbide slitting knives at work, we used one cup wheel and did the roughing at medium speed and the same wheel becomes "fine" when you increase the speed , which we did.
            So a 60 can do finishing work, or conversely use a 100 at slower speeds for roughing passes
            Rich
            Green Bay, WI

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            • #7
              So 180 would be way too fine

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              • #8
                Originally posted by Richard P Wilson View Post

                Strange, I've been using a green wheel for carbide for 30 years, and no one ever told me it didn't work----
                I didn't say that they absolutely do not work. I said they don't work well.

                JL.....

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                • #9
                  Originally posted by plunger View Post
                  So 180 would be way too fine
                  it would be okay for a final finish pass, but it's going to generate a lot of heat and you be better off using cooling.

                  JL.....

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                  • #10
                    Originally posted by plunger View Post
                    So 180 would be way too fine
                    That's what I use. Good finish on tools, but not going to be an aggressive roughing wheel. Nice inbetween grit for tool grinding.

                    I agree with Joe Lee, the green wheels are terrible and old fashion way of grinding. Diamond wheels have come down in price over the years. My Chi-com 180 wheel was $ 20.00 on ebay and works well.

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                    • #11
                      I recall being told 18 years ago in shop class that green SiC wheels were "the only way to grind carbide" unless you could afford diamond. Thankfully diamond is incredibly cheap now, even cheaper than any SiC I can find today.

                      I have a half dozen diamond wheels for grinding carbide now. Most are 4in nominal for my d-bit and came from Shars, however I have gotten a couple more from Banggood and Amazon. I also have as many CBN wheels for doing HSS.

                      Beware of the common issue of dimensional problems with the really cheap ones. I had to grab the abrasive surface on one and remachine the mounting bore and face to get it to run true. Even then, it wobbles some because the cutting face is not flat. I use that one for sharpening tungsten electrodes only now.

                      For carbide, you can get far with a 120 or 150 grit if you have an extra fine ez-lap or some other kind of honing stick for doing the final cleanup.

                      I have one electroplated(?) diamond wheel that is not like the rest of the resin bonded ones and it cuts 20x better than the resin ones. It cost 3-4x more than the rest but it's worth it IMO.

                      Does anybody here have experience with dressing and cleaning diamond wheels? I need to get some dressing sticks and have found a variety of conflicting advice wrt/ what to get, what grit to use, how to do it...
                      -paul

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                      • #12
                        Yes, the dressing process will vary depending on your wheel's bond type. Most of the Chinese wheels will probably be resin bond. Those are best dressed with a molybdenum stick. This works to pull diamonds out of the bond, truing the wheel so it doesn't run out any more. Use it just like a diamond dresser is used with a normal grinding wheel. If you can't get molybdenum, a piece of steel will work too but not as well.

                        After that you will need to "stick" the wheel with a stick of aluminum oxide (basically a small honing stone or chunk of grinding wheel) to expose the abrasive particles such that they are sticking out past the bond. Use a grit either similar to or a little coarser than whatever the wheel is. To do this you just press the stick straight into the wheel as it rotates. Chewing through about ⅛" of stick should do the job. If the wheel subsequently seems as thought is it's loaded, stick it again. You may need to do this fairly frequently depending on what you're grinding.

                        Electroplated wheels can't be dressed, of course. Metal bond wheels basically have to be ground down with a silicon carbide wheel, then sticked in a little different fashion.

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                        • #13
                          Originally posted by Fasturn View Post

                          That's what I use. Good finish on tools, but not going to be an aggressive roughing wheel. Nice inbetween grit for tool grinding.

                          I agree with Joe Lee, the green wheels are terrible and old fashion way of grinding. Diamond wheels have come down in price over the years. My Chi-com 180 wheel was $ 20.00 on ebay and works well.
                          Forrest Addy used to describe the green wheels as "clubbing off" material, not really cutting anything. His comment was that there were as a result, micro cracks on the edge of the carbide.
                          2730

                          Keep eye on ball.
                          Hashim Khan

                          Everything not impossible is compulsory

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                          • #14
                            Yeah they really suck after having used diamond wheels. For any real material removal anyway. They do a passable job for a light finishing touch if you have a newly dressed sharp wheel, but the dress does not last long at all, and I am in complete agreement with Forrest. For grinding carbide they need to have a pretty soft bond or they don't do much but create a lot of heat, which can easily create those micro-cracks, especially when dipping in water to cool off the tool. So when using them when they're a soft enough wheel there's generally a huge cloud of dust and flying grit. I used one at a friend's shop a few weeks ago to rough grind some carbide before finishing on a diamond wheel and ended up losing probably ½" or more off the wheel diameter and with a pile of wheel grit on the floor sizeable enough that it had to be swept up with a broom. And arms completely covered in it as well. Not so good around other precision machinery...
                            Last edited by eKretz; 08-23-2021, 05:24 AM.

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                            • #15
                              What if I have a brazed carbide tool that i want to re-shape? Then I need two different grinders? I thought you couldn't do steel on diamond?
                              25 miles north of Buffalo NY, USA

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