At 08:48 AM 5/28/99 -0400, you wrote: >> When you turn a front rail pin you inevitably get a smaller contact surface than if the pin "flats" were parallel to the bushings. > >Ron, think about this. > >Take a pin and cut it and look at it's cross section, you will see >what I mean. > >The pin is shaped like a ball with the center section removed. This >is effective and inexpensive to produce. Rotating the pin to take up >some lost motion is perfectly acceptable unless the bushing is >severely worn. * Hi newton. Yea, I know. That was my first post, which I screwed up by not saying what I was thinking. My apologies. If my second post didn't do any better, I'll try again. You're right. With a new bushing, turning the pin won't decrease the contact area, it just moves the contact point forward on one bushing and backward on the other. With a worn bushing, turning the pin decreases the contact area quickly, unless the key is very pully too. >The only time you will get a smaller contact area for the bushing is >if the pin has a parabolic curve (absolutely useless and VERY >expensive to produce) or a pin with a cheap rectangular cross section. > >The radius of the pin is constant on both sides so a rotation of the >pin will present a constant tangent to the bushing _until_ _that_ >radius terminates. * With a new bushing in a clean mortise, yes. With a worn bushing, the contact area moves to the "point" at the edge of the pin wear track in the bushing surface. > >I prefer to rebush key myself because I do a better job than most but >I still get some variation of fit which I will equalize by turning the >pins slightly. > >Most pins do NOT have a consistent vertical shape so I test bushing >and pin fit at the rest and depressed positions. > > Newton * I noticed just such a condition on the pin I measured to get that 0.010" @ 20 degree figure in my second post. It's bigger at the top. I have a question. Why does that slop that can be taken up with a little pin turn feel and look so much bigger than the mic says it is? Ron
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