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  • dressing spring caliper tips

    From Cydrome Leader@21:1/5 to All on Tue Oct 24 23:55:39 2023
    Does anybody have some old timer stories about how to grind and dress the tips of spring ID or OD calipers? Was
    there ever and sort of standard for this? The quality of newly made ones seems really, really poor.

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  • From Jim Wilkins@21:1/5 to All on Thu Oct 26 08:08:42 2023
    "Cydrome Leader" wrote in message news:uh9lhr$mh8$[email protected]...

    Does anybody have some old timer stories about how to grind and dress the
    tips of spring ID or OD calipers? Was
    there ever and sort of standard for this? The quality of newly made ones
    seems really, really poor.

    ------------------------

    A belt sander with the platen carefully squared to the table does a nice job
    of squaring hardened steel. You can lightly close the tips on sandpaper to
    cut them parallel. Like grinding HSS lathe bits it requires some user skill
    and practice. I've learned to grind broken taps and screwdrivers to a
    conical or pyramidal point, which is useful to salvage them into scribes, drifts and reamers. The shape of the tip, pointed or flattened, gives
    immediate feedback to how symmetrical it is.

    It's said that Henry Royce could file a brass hubcap into a perfect octagon
    by eye. Rolls was the businessman, Royce the engineer.

    I practiced holding partly ground lathe bits and other tools against the
    motor housing to develop the skill of keeping them steady in position and grinding the entire surface all at once. When I took a night class in
    machine shop the instructor was annoyed that my practice lathe bit looked better than his.

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  • From Leon Fisk@21:1/5 to Jim Wilkins on Thu Oct 26 08:51:16 2023
    On Thu, 26 Oct 2023 08:08:42 -0400
    "Jim Wilkins" <[email protected]> wrote:

    <snip>
    A belt sander with the platen carefully squared to the table does a nice job >of squaring hardened steel. You can lightly close the tips on sandpaper to >cut them parallel. Like grinding HSS lathe bits it requires some user skill >and practice. I've learned to grind broken taps and screwdrivers to a >conical or pyramidal point, which is useful to salvage them into scribes, >drifts and reamers. The shape of the tip, pointed or flattened, gives >immediate feedback to how symmetrical it is.

    Checked some old texts in my stash and didn't find anything on that
    specific subject...

    From this old Machinery's Reference book it seems like it wasn't
    uncommon to bend them into different shapes and dress the tips to fit a
    certain job🤷

    https://archive.org/details/measuringtools00newyrich/page/10/mode/2up

    --
    Leon Fisk
    Grand Rapids MI

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  • From Jim Wilkins@21:1/5 to All on Thu Oct 26 09:55:53 2023
    "Leon Fisk" wrote in message news:uhdnc5$1jblr$[email protected]...

    Checked some old texts in my stash and didn't find anything on that
    specific subject...

    From this old Machinery's Reference book it seems like it wasn't
    uncommon to bend them into different shapes and dress the tips to fit a
    certain job🤷

    https://archive.org/details/measuringtools00newyrich/page/10/mode/2up

    Leon Fisk

    ---------------------

    I have one that a previous owner reground from possibly inside to a conical point and a rounded sharp edge for scribing circles.

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  • From Cydrome Leader@21:1/5 to Jim Wilkins on Fri Oct 27 02:00:59 2023
    Jim Wilkins <[email protected]> wrote:
    "Cydrome Leader" wrote in message news:uh9lhr$mh8$[email protected]...

    Does anybody have some old timer stories about how to grind and dress the tips of spring ID or OD calipers? Was
    there ever and sort of standard for this? The quality of newly made ones seems really, really poor.

    ------------------------

    A belt sander with the platen carefully squared to the table does a nice job of squaring hardened steel. You can lightly close the tips on sandpaper to cut them parallel. Like grinding HSS lathe bits it requires some user skill

    For the flat style, do you just leave the tips completely parallel like
    wire nippers, or round the edges a bit? The ones I was using were of the
    round type, with round tips, never had and issues. Now that I have access
    to larger lathe, I can use the larger ones made from flat stock, and they
    feel terrible.

    and practice. I've learned to grind broken taps and screwdrivers to a
    conical or pyramidal point, which is useful to salvage them into scribes, drifts and reamers. The shape of the tip, pointed or flattened, gives immediate feedback to how symmetrical it is.

    It's said that Henry Royce could file a brass hubcap into a perfect octagon by eye. Rolls was the businessman, Royce the engineer.

    I practiced holding partly ground lathe bits and other tools against the motor housing to develop the skill of keeping them steady in position and grinding the entire surface all at once. When I took a night class in
    machine shop the instructor was annoyed that my practice lathe bit looked better than his.

    Nice.

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    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jim Wilkins@21:1/5 to Jim Wilkins on Fri Oct 27 07:00:42 2023
    "Cydrome Leader" wrote in message news:uhf5kq$ec6$[email protected]...

    Jim Wilkins <[email protected]> wrote:
    "Cydrome Leader" wrote in message news:uh9lhr$mh8$[email protected]...

    Does anybody have some old timer stories about how to grind and dress the tips of spring ID or OD calipers? Was
    there ever and sort of standard for this? The quality of newly made ones seems really, really poor.

    ------------------------

    A belt sander with the platen carefully squared to the table does a nice
    job
    of squaring hardened steel. You can lightly close the tips on sandpaper to cut them parallel. Like grinding HSS lathe bits it requires some user
    skill

    For the flat style, do you just leave the tips completely parallel like
    wire nippers, or round the edges a bit? The ones I was using were of the
    round type, with round tips, never had and issues. Now that I have access
    to larger lathe, I can use the larger ones made from flat stock, and they
    feel terrible.

    --------------------------

    I should have mentioned that sanding the contact surfaces parallel refers
    only to outside calipers, and tweezers for fine work such as handling tiny surface mount components.

    My 8" Starrett dividers which are flat stock and apparently unmodified have
    the tips ground conical at an angle that lets the tips touch. For scribing circles I prefer the modified dividers with one point conical and the other flattened like a duck bill, so it has the longer curved edge of an Ulu
    knife.

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