Marv sez:
" I have no idea what it's official name is. I just call mine a "centering
gizmo".
It is a takeoff on a 3-pin device called "The Preacher" that clock makers
have been using for a long time. (From one of W.R. Smith's books on the
subject.) In the preacher there are three pins closely spaced to go among
the pinion holes in a clock plate. One of the pins was conical shaped to
fit the range of pinion holes in any particular clock. The other two pins
were sharp pointed. The clock maker would use the preacher to locate exact
center of worn bearing or pinion holes. The conical pin was inserted in the
worn hole and 2 centers were punched with the other 2 pins. Then the
clockmaker goes about the job of drilling out the old hole and pressing in
new material in the form of a stock, or custom made bushing. After dressing
the bushing to the clock plate, the preacher is brought up to fit in the 2
previously center punched holes. Then the conical pin is punched with great
assurance it will be located in the same place as the original hole.
Bob Swinney
"Marvin W. Klotz" wrote in message
...
On Fri, 08 Apr 2005 08:18:50 -0700, Grant Erwin
wrote:
a6016 wrote:
A friend, who died of cancer about a year ago, was working in his shop
one day while I looked on. He was drilling a hole in a piece of 2"
square tube to make into a trailer hitch. He had a little tool or
device that he used to find the center, side to side, to drill the hole
into which the retaining pin would be inserted and secure the hitch.
Does this "thing" sound familiar to anyone? I'd like to find it for my
own use.
They're easy to make.
Imagine a bar with two pins set into it. Pin-to-pin separation is greater
than
the width of the material in question. Imagine a hole to accept a
transfer
punch drilled in the bar midway between the two pins.
Drop over material, twist until both pins contact the sides of the
material,
and the hole will be centered on the material. Insert transfer punch in
hole
and make center mark.
I made one with the added feature of adjustable pin spacing and it's
useful for
non-precision jobs.
Regards, Marv
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