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Wheel suitable for a bench grinder?

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  • Wheel suitable for a bench grinder?

    Picking up where my bit critique left off, would a wheel like this work on a 6” bench grinder assuming proper bushings etc? Anyone know of other quality brands with similar offerings?

    http://www1.mscdirect.com/CGI/NNSRIT...MT4NO=20954352

    I’m going to need a new wheel soon and I want something that can rough remove material at a decent rate.
    Last edited by dan s; 04-11-2007, 07:10 PM.
    -Dan S.
    dans-hobbies.com

  • #2
    The blue SG wheels are really meant for cool cutting on very hard materials like D2 and the like on a surface grinder.

    I see no reason why it wouldn't work with HSS, but as they cost about 3 times more than an equivalent Al Ox wheel would you really need it on a bench grinder?
    I doubt you would see much performance increase in this application.

    I have one I tried on my surface grinder and it behaves like a very hard wheel, even though it is supposed to be more friable and 'self-sharpening' than the standard Aluminium Oxide. I've tucked it away in the corner until I have something *really* hard and just use the Norton 38A wheels for most purposes.

    On my 2 bench grinders I still have the grey and brown el-cheapo wheels that they came with, and these are fine for grinding toolbits and drills and anything else thats gets thrown at them.

    Peter

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    • #3
      Peter,

      Currently I’m using Norton “Premium White” Bench Wheels (60 & 100 grit), most likely similar to the 38A type. What’s you opinion on the 32A wheels? According to Norton they are designed for faster removal of stock.
      -Dan S.
      dans-hobbies.com

      Comment


      • #4
        Dan, I've never tried a 32A so can't comment directly. The premium white wheels will cut very well, but are very friable so of course they will wear quite quickly.

        However, when I was talking to a Norton rep about wheels for a home shop surface grinder, he did comment that if you want to save money and buy just one wheel that will do most everything, than a 32A was the one to have.

        Have you looked here?
        http://www.ind.nortonabrasives.com/D...00000000001823

        There are some guides on there as to selection, but as I said before I just use the bog-standard bench grinder wheels that came with mine, medium one side, fine on the other, they work well on most things and have a lot of wear left in them. When they do eventually wear out I'll probably replace them with the same.

        Peter

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        • #5
          Wheel color only means what a particular manufacturer wants it to mean. There isn't any standard for grinding wheel colors and the color is produced by dye added to the abrasive, not the abrasive itself in most wheels. Silicon carbide is naturally grey so cannot be dyed light colors. Aluminum oxide is white so it can be dyed any color you wish including blue and ruby as well as brown.

          The stock removal rate of a particular abrasive such as aluminum oxide depends not just on the grit size but the grit density. An "open" wheel will remove stock faster than the same grit in a denser wheel but the denser wheel will last longer.
          Free software for calculating bolt circles and similar: Click Here

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          • #6
            the one i use a red wheel, I've heard them referred to as ruby wheels, not sure where to send you for it - just read what Evan said re colour, make sense, so maybe the colour is irrelevant. Mine was given to me by an old hand. it is very fast cutting, friable, as Peter points out. Still, I found they last a loooong time as home shop use is not that demanding. I left one of the grey wheels on the other side for general propose stuff. imo you'll be happier with a courser grit. went out and checked mine, its a Simonds RA 46 I8 V8 8x.75/1.25 (so likely meant for a surface grinder)
            .

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            • #7
              The 32A wheels will seem a lot "harder" than a 38A. They don't break down as easily as a 38A does. On a bench grinder you would probably notice it heating up your part more, possibly loading up. Using a bench grinder, you are usually touching up tools, resharpening and such, and you won't be cutting heavy enough to break down the bond. It (32A) will maintain it's shape better, however (sharp corners).

              The SG wheels wouldn't be a good choice for a bench grinder IMHO. They seem very hard when grinding and they are expensive. I've used them for surface grinding; but only on certain applications.

              Kevin

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              • #8
                I have been looking into this for a while now, and my notes are:

                Abrasive: (A) Aluminum Oxide
                Grain Size: 50 – 120
                Grade: H – L
                Structure: 4 – 6
                Bond Type: (V) Vitrified

                I always take manufactures recommendations with a grain of salt, but Norton recommends the following.

                HSS & Tool Steel RC 50-68 with a narrow contact area

                For the different compounds they say:
                • 5SG - High-performance proprietary seeded gel ceramic aluminum oxide abrasive / Self-sharpening abrasive
                • 32A - Sharp monocrystalline aluminum oxide grain – the industry's most versatile abrasive
                • 38A - Friable abrasive grain

                As expected prices align with recommendations.
                -Dan S.
                dans-hobbies.com

                Comment


                • #9
                  Do the recommendations specify if this is for surface grinding or other?

                  I see narrow contact area mentioned, which leaves you to determine what "narrow" is relative to what you are working with, I suppose.

                  With a SG wheel, I haven't tried anything wider than 1/4" on the surface grinders due to the heating. The SG wheels do seem to work well for deep cuts with light infeed; but this has nothing at all to do with bench grinders.

                  The 32A 46 KVBE would make a good general purpose wheel for sharpening tools, maybe a little hard for softer steels.

                  Kevin

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                  • #10
                    Kevin,

                    the quote is from this PDF (page 3 under "TOOL RESHARPENING")
                    http://www.ind.nortonabrasives.com/M...References.pdf

                    for surface grinding they recommend

                    • J for narrow contact
                    • I for medium contact
                    • G for wide contact
                    -Dan S.
                    dans-hobbies.com

                    Comment


                    • #11
                      A 32A and a 38A wheel are both aluminum oxide wheels known as combination wheels. They contain a combination of coarser and finer grit. The only difference besides dye color is the 32A has a slightly higher proportion of coarse to fine than the 38A. The difference is minimal.

                      Aluminum oxide wheels age harden slowly. This can account for apparent differences between wheels that would otherwise be similar. Ten years on the shelf can increase hardness by two grades.
                      Free software for calculating bolt circles and similar: Click Here

                      Comment


                      • #12
                        Tonight I needed to grind 3 bits for a project, so I took photos to show the problem I have.

                        background info:

                        The wheels I’m using currently:
                        http://www1.mscdirect.com/CGI/NNSRIT?PMAKA=07554629
                        http://www1.mscdirect.com/CGI/NNSRIT?PMAKA=62391800


                        My current grinding set up.



                        Before I started grinding I dressed the wheels with a single point diamond. After insuring the wheels where clean and true I started shaping bits. The next two photos are after grinding the front and side relief on 3 3/8” bits. These particular bits are Chinese hss, but the wheels look the same even if I’m grinding quality bits.

                        60 grit


                        100 grit


                        When I get new wheels I will get courser ones; but why does this 60 grit wheel load up so fast? It works great right after it’s dressed, but two minutes later it’s loaded. I don’t need to dress it every 2 or 3 minutes do I?
                        Last edited by dan s; 04-13-2007, 02:23 AM.
                        -Dan S.
                        dans-hobbies.com

                        Comment


                        • #13
                          If I want to grind off a lot of metal I grab my 4" angle grinder. It just seems to cut so much easier than the 8" bench grinder. Is it the higher rpm or the coarser wheel?

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                          • #14
                            I'm just learning about a lot of this stuff, but is it possible that the grinder is spinning too fast?

                            As I think I understand it, the following is true:

                            Turning a wheel too slow will cause it to break down faster and act softer. Turning it too fast will make it act harder and have more tendency to load up.

                            Also, a wheel with too tight a grain structure, not having enough voids, will also cause loading. The links seem to indicate no-name wheels intended for your application, and if it was Norton or the like then I wouldn't tend to question whether it was applicable as stated, but maybe not in this case?

                            <shrug> That's my best guess, but unfortunately, just a guess...
                            Russ
                            Master Floor Sweeper

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                            • #15
                              Changing surface speed on a grinding wheel does have an effect on the apparent "hardness" to an extent; but I can't remember ever having seen it done on a pedestal grinder.

                              If you want to stay with the 60 grit for roughing, try dropping to a 60-I. Maybe try using a 46-I for roughing and the 60 for finishing. It would depend on the surface finish you are trying to get; but IMO 100 grit wheels are a little overkill for a bench grinder.

                              The 60-J wheel you are using now isn't breaking down fast enough.

                              Just my $.02!

                              Kevin

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