<VV> freeing stuck parts

[djtcz at comcast.net]

snipped and bottom posted 

-------------- Original message -------------- 
In a  message dated 8/11/2008 9:01:35 A.M. Pacific Daylight Time,   
dkdewald at pasty.net writes:

At  21:20 8/10/2008 -0400, Marc  Sheridan  wrote:

>>snip<<
>My bicycle has an  aluminum seat  post in a steel seat tube. While looking 
for  a
>creaking noise, I  discovered that I forgot to use anti-seize in  this
>situation, because  the seat post won't  budge
>
>Has anyone found a way or a  chemical that will  break that bond? I've been
>shooting PB Blaster on  it everyday for  weeks and it still won't move. Heat
>is out of the  question  because it would ruin the paint and I can still ride
>it the  way  it is. I'd just like to get it freed in case I do want to   
adjust
>it for some reason.

I've had pretty good results heating bolts that were stuck, then letting things cool off.  I believe it works so well on steel parts because iron oxide is less dense than the steel it came from (more volume, and why things ge tightened up and seize ) and weak, so when the hot bolt swells up the rust is crushed to some extent, reducing the "press fit" when temps and dimensions return to normal.
I could not find if aluminum oxide is less than dense than aluminum (2.7 g/cc), but I'm thinking the steel frame ID may be what rusted anyhow.
I'd remove the seat, and heat the aluminum post aggressively with a propane torch being careful to keep the temp near the epoxy cooler than I can touch (I'd keep a bucket of water with a few rags in it close by to limit the frame temp). Let cool for an hour and repeat a few times. 
Sometimes impact breaks rusted parts free, but sometimes a steady force is better. If the steel post is welded to the bottom set I might try "torquing" the post to loosen with the crank held n a vice
Is there a hole in the alum seat post? Maybe it can be tapped 1/4 inch or bigger to provide a good purchase for a puller made from a bolt, thick washer, and a steel tube that just slips over the alum post to push against the frame.  
http://www.toolsource.com/prod_medium/102839.jpg
It does not take much bolt torque to exert 1000s of pounds of force.


Dan Timberlake 
Westford, Massachusetts, USA