Action Center Pin Progression

[Greg Graham]

My only exposure to the use of long center pins was a
class at NYSCON 2003 taught by Ken Walkup called:

"Rebushing Action Parts Using the Renner System".

The long pins, which he called "Shrink Pins", come in
mm sizes 1.25, 1.275, 1.3, 1.325, and 1.35, 60 cm
long.  I ordered some from Renner USA, item number
GEN-0610, which were about $2.50 each in Oct '04.  Ken
suggests buying at least 3 of one size to fit 88
parts.

The idea was that an entire rail of parts could be
rebushed efficiently by using the Renner pre-glued
cloth (Renner part 1049, get six strips per rail),
pulling the cloth thru the bushing, pulling on the
next part and leaving 1/16th inch between parts until
the cloth is full.  Cut the cloth flush with the left
side of each part to separate them, and slide them on
the shrink pins.  Start the pins by hand, then use
pliers to pull the pin.  The first 3 inches of the pin
must be tapered and roughened (by you) to ream the
bushing to size.  Polish the pins before you start
sliding on bushings, so your first parts don't end up
full of tarnish gunk.  Fill up the pins with parts. 
It takes three pins to do an entire rail of parts.  

Soak the pre-glued cloth with an equal mix of alcohol
and water to activate the glue and size the wool. 
Leave them overnight to dry.  They will be very loose
on the pin when done.  Slide them off, trim the excess
bushing cloth, and re-pin as normal with regular pins.
 

Ken says to use a shrink pin one size smaller than
your new center pin, or about the same size as the
original pins you took out, since you often choose a
new pin about .001" or .025mm larger than what was in
the birdseye originally.  

This was a good class, and included many more tips on
production-efficiency pinning, when to do it or when
to buy new parts instead, etc.  The point of the long
pins was simply to keep speed up, individual pin
handling/reaming/burnishing down.  He certainly didn't
recommend using the long pins to assemble the finished
parts.  Sliding a birdseye down a two foot pin doesn't
sound like a good idea to me, but that's my LEHO
(limited experience humble opinion).  

Greg Graham


		
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