negative rake scraper

Discussion in 'Newbie' started by Dave Fritz, Nov 17, 2016.

  1. robo hippy

    robo hippy

    Joined:
    Aug 14, 2007
    Messages:
    1,865
    Location:
    Eugene, OR
    The robo rests do have an angle scale. To get the most accurate angles, the platform, when set to 90 degrees should be even/level with the center of the wheel hub, and 1/8 inch away from the wheel (indicator line for that). I would guess John is using the 35 degree angle setting. Every grinder sets up a little different, so getting machine shop accurate angles is next to impossible. Getting them close and exactly repeatable does happen. If John's rest is a hair high, or a hair back from the ideal set up, that would make it a bit more acute (?not sure, but more pointy...). A 1/2 inch piece of plywood changes the angle about 5 degrees more shallow, so 35 would become 30..

    John, some times to remove the old burr, I use a burnishing tool and a light pass or two. My NRSs are a 1/4 round profile so they can go in either direction. With a half round or ) profile, you could go either direction, and wouldn't need to flip it over. Dang, now I might have to buy another scraper or two....

    robo hippy
     
  2. john lucas

    john lucas

    Joined:
    Apr 26, 2004
    Messages:
    5,822
    Location:
    Cookeville TN USA
    Bill You set the Robo rest at 90 degrees and there is a horizontal line that you set to match the face of the wheel. That should give you a repeatable angle but I haven't checked to see where it comes out on the wheel, at, above, or below center. Well I'm pretty sure it's at or above center. I'll try to remember to look tomorrow.
     

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