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Re: Europa-List: Pin interferece

Subject: Re: Europa-List: Pin interferece
From: rparigor@suffolk.lib.ny.us
Date: Sun, 24 Jun 2007 19:12:06

Hello Willie

"> For what its worth, my inspector, Tony Kay, tells me he suspects that  
> the torque tubes supplied have a variable degree of heat treatment,  
> leading to some folk experiencing more "wear" in the holes than  
> others. I don't think he has hard data to back his suspicions, only  
> the observation that some torque tubes do better than other. Anyone  
> else have views or info on this?"

Making a round hole with walls that are flat is not a trivial job. I
reamed my holes holding parts in a fixture on my Milling Machine. I used
plenty of cutting fluid, and a few reamers where the last one was very
close in size where it only took a few thousands cut. 

If you were to measure this now what you think is the perfect hole and
made a pin to fit, you would be dissapointed (as was I).

I turned some mini pins growing in size ~ .0001" and forced them in place
in growing incrments till a light tap wass needed. In every case to hole
would grow in diameter! Some as much as .0006" , some as little as 1 or 2
tenths. Now I used my precision pins to measure holes and make pins to
fit.

Search Ron Parigoris torque tube for a prior post. 

You need to make holes at worst the same size entrance and exit and
dogbone pin, but better to make entrance hole a slight bit larger (a
thousand or 2), this way there will be no wear on the first hole dragginfg
a full length pin through it.

416SS is pretty easy to cut, and using double sticky tape on a flat G-10
or popsicle stick with wet/dry sandpaper to hand lap works great. 

Ron Parigoris



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