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.

"Cydrome Leader" wrote in message news:uh9lhr$mh8$1@reader2.panix.com...

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.

On Thu, 26 Oct 2023 08:08:42 -0400
"Jim Wilkins" <muratlanne@gmail.com> 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

"Leon Fisk" wrote in message news:uhdnc5$1jblr$1@dont-email.me...

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.

Jim Wilkins <muratlanne@gmail.com> wrote:
> "Cydrome Leader" wrote in message news:uh9lhr$mh8$1@reader2.panix.com...
>
> 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.

"Cydrome Leader" wrote in message news:uhf5kq$ec6$1@reader2.panix.com...

Jim Wilkins <muratlanne@gmail.com> wrote:
> "Cydrome Leader" wrote in message news:uh9lhr$mh8$1@reader2.panix.com...
>
> 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.