"Ed Huntress" wrote in message
...
"Robin S." wrote in message
. ..

"steve" wrote in message
oups.com...
Not sure this is the right newgroup to ask but what the heck. I am
working on a project where I need to fasten two small objects together
with precise orientation (.5 degrees). The objects will be taken
apart
and put together frequently so the fastener cannot be permanent.

As others have suggested, dowel pins are specifically made for this
appliction.

However, you need to consider who will be assembling/disassembling the
product in question, and whether they're capable of taking the
appropriate
care required to not bugger the dowel/hole fit.

While a pair of dowels will allow repeatability within a couple
ten-thousandths of an inch, there is a significant risk that an
untrained
operator will incorrectly assemble the joint and (typically) use the
dowel
to "shear" its mating hole due to the dowel entering on an angle. Once
this
has occured, the hole will require rework to function correctly.

There are ways to minimize the risk. Having the appropirate hole size is
important (precision slide fit as opposed to a light press fit), using a
relieved dowel pin, using one standard pin and one diamond pin...

Holy cow. Does anybody still use diamond pins? That's what they used
decades
ago to assemble master jigs and master watch plates, but I thought those
things disappeared.

Did they teach you about watch plates in your tooling classes? That was
once
the ultimate expression of the toolmaker's art.

--
Ed Huntress


It's been a few years (ok, more than 20) since I last built tooling, but I
was still using them at that point in time. I can't imagine not using them
when the situation calls for them. They're the ultimate for fitting more
than one item to the same set of pins.

Harold