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Thread: Sharp chisels!

  1. #46
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    Thanks for the feedback Mel. That may explain why the original box for the QC stone is labelled " can be used with oil or water ". With regards the other honing stone; I have an vague idea these were originally marketed as Aloxite Combination Stones. I did find this early Popular Mechanics advertisement under the heading; "Sharp tools do a better job" https://books.google.com.au/books?id...0stone&f=false

    Stewie;
    Last edited by Stewie Simpson; 06-01-2016 at 1:05 AM.

  2. #47
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    Question to the forum; if you have a 5 inch grinder that's rated at 2975rpm; what is the resulting change in rpm if you were to remove the guards and fit a larger dia. 6 inch cbn grinding wheel to it. Note: cbn wheels start at 6 inch dia; cbn wheels are rated up to 3000 rpm.

    Stewie;

  3. #48
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    Quote Originally Posted by Stewie Simpson View Post
    Question to the forum; if you have a 5 inch grinder that's rated at 2975rpm; what is the resulting change in rpm if you were to remove the guards and fit a larger dia. 6 inch cbn grinding wheel to it. Note: cbn wheels start at 6 inch dia; cbn wheels are rated up to 3000 rpm.

    Stewie;
    There is no change in RPM but the velocity of the surface of a 6 inch wheel is higher than for a 5 inch wheel. The ratio of the diameters will tell you how much faster (6/5 = 1.2) 20% higher surface speed for 6 inch wheel as compared to 5 inch wheel.
    \
    Note - it may take a bit longer for the 6 inch wheel to spin up to rpm if it is heavier or if the weight is distributed non uniformly to the outside of the new wheel.
    Last edited by Pat Barry; 06-01-2016 at 7:55 PM.

  4. #49
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    Thanks for the feedback Pat. Excellent.

    Stewie;

  5. #50
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    Quote Originally Posted by Pat Barry View Post
    There is no change in RPM but the velocity of the surface of a 6 inch wheel is higher than for a 5 inch wheel. The ratio of the diameters will tell you how much faster (6/5 = 1.2) 20% higher surface speed for 6 inch wheel as compared to 5 inch wheel.
    \
    Note - it may take a bit longer for the 6 inch wheel to spin up to rpm if it is heavier or if the weight is distributed non uniformly to the outside of the new wheel.
    This is 100% right. Even when CBN wheels are the same radius they take longer to spin up/down because they're heavier and have more mass at the edge (and therefore much higher rotational inertia).

  6. #51
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    Quote Originally Posted by Stewie Simpson View Post
    Thanks Patrick; if you run the 5 inch grinder with a 6 inch cbn wheel on 1 side, and a 5 inch silicon carbide grinding wheel on the other side, is that likely to cause any vibration or balance issues within the grinder due to a potential difference in centrifugal force.

    Stewie;
    It's been a long time since I've been a practicing ME so this is probably a semi-qualified opinion, but... There shouldn't be any problem provided that the bearings are in good condition and the SiC wheel is reasonably true. What matters is balance about the axis of rotation, and you're not proposing to change that.

    I ran one of my 8" grinders "unbalanced": that way (8" AlOx on one side, CBN on the other) for quite some time and never saw any trouble.

  7. #52
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    Thanks Patrick; appreciate the feedback.

    Stewie;

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