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ratio of grinding wheel to metal removal volume.

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  • ratio of grinding wheel to metal removal volume.

    I made a diy surface grinder that actually turned out fairly well in that i was able to get .001" flatness over a 9 by 24" inch area.
    I was flattening about 120 square inches of probably cold rolled steel and removed probably 3 cubic inches using a 3/4" thick wheel that started out at about 7" diameter and ended at 4.75" directly driven by a treadmill motor. the wheel was probably a 60 grit, originally the fine wheel that originated from a harbor freight 8" benchgrinder


    Spraying water on the steel the whole time (which was nessisary as the steel is epoxied to granite), the ratio works out to be about 5:1 volume of grinding wheel lost to steel removed. i'm wondering if this is normal, or if substantially better should be the norm. as far as surface speeds i was running it at.. probably half of what is normal for an 8" wheel at 3600 rpm, ending at a third of what is normal. i don't think i had 2000 rpm on the motor even at 5" diameter, and starting out i probably had 1500 rpm at 7 inches. I would have run it at far higher speeds but I could only just exceed the first harmonic of the resonance of the entire structure.

    as for the metal removed it seems most of it ended up as a fine powder of metal.

  • #2
    Google for ”grinding g-ratio” for some numbers. Ratio of material removed to wheel wear so inverse your numbers.

    AFAIK your G-ratio is really on the low side, 10:1 to 500:1 might be expected range for alumina wheel on steel.

    Harbor freight mystery wheel would be my biggest suspect.

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