"Jim Stewart" wrote in message
...
Ed Huntress wrote:
"Bob Engelhardt" wrote in message
...
A taper pin is so much more work to use - is it that much better than a
split pin (aka spring pin)? Or, putting it another way, in what
circumstances would a split/spring pin be inadequate and a taper pin be
required?

Thanks,
Bob

Roll pins (spring pins) are made to keep things from falling apart. Taper
pins are made for precisely locating parts relative to each other.

For example, a roll pin might be used to hold a flexible joint onto a
shaft. A taper pin (or pairs of them, actually) might be used to locate
the sections of a multi-part stamping die on a common die plate.

There has been some inappropriate use of taper pins in the past. Today,
there is some inappropriate use of roll pins. Roll pins flex and have
limited ability to locate. But their shear strength is adequate for many
jobs that formerly depended upon straight pins.

A taper pin in AL, subject to shock loads, will
flex and batter the walls until failure. Not a
pretty sight.

Sure. But that's not the pin's fault. That's an inappropriate use of a
pin -- any kind of pin of that size. The problem there is that the material
(aluminum) doesn't have sufficient compressive yield strength for the chosen
fastener/locator: the pin.

Since a steel pin has roughly 3X the stiffness (Young's Modulus) of the
aluminum, and many times its strength, it's probably a case of the aluminum
yielding locally.

--
Ed Huntress