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and let that be a (grinding) lesson for you!

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  • and let that be a (grinding) lesson for you!

    I've been doing a lot of fooling about / experimenting with the surface grinder.

    I've got a few import "angle plates" of various sizes around and I thought I'd
    turn one into a project. Get it as a square and parallel as possible.. and maybe
    with some luck turn into SG tooling instead of milling machine.

    These are cast iron, factory finish is a fast fly-cut.. this one has already
    been ground but original squareness was about 2 thou out.

    I'm measuring squareness with a surface gage and ball bearing. I need to
    convert my surface gage some day, gets tiring chasing that ball around:


    My reference is a small granite 'knee'


    initial results were quite frightening.. a hair over 0.0005" out (measuring about 1.5" up).
    better than before but what was happening?


    started to really worry about the result of my grinder restoration.
    did I really foul this one up? had I fooled myself during the rebuild?
    what could've gone wrong?

  • #2
    took a step back and had a look at the machine.
    cleaned and stoned the mag chuck. wiped down all the parts, and
    tried it again.

    same results.. a bit over 0.0005" ..

    so I decided to check my grinding vise. I knew it wasn't the bees kness
    but I have faint recollection of buying it with a 0.0002" spec.

    its one of these screwless types:


    measured it for the first time...


    thats 0.0015" on the side of the fixed jaw!

    and 0.001" on the end face:


    so maybe this isn't a surprise to anyone.. and in hindsight I suppose it was the obvious
    thing to check.. but I'll tell ya it was one hell of a roller coaster ride.

    I mean the darn thing is so shiny how could it be so out-of-square?!

    I plan on measuring out the rest of the vise to see if any of it is parallel / square / flat.

    I don't know if I have what it takes to clean this vise up.
    Especially if "what it takes" is a good vise to begin with!


    • #3
      Tool Making 101, Validation Validation & Validation.

      Process of elimination, served you well.


      • #4
        Once you know how much the vise is out, you should be able to shim the angle plate in the vise to compensate. Yes?


        • #5
          Those little rare earth magnets in the vee of the surface gauge help stop your only ball escaping under the bench!, i reckon theres a bloody spider under mine the size of a cat, the bugger eat the mice