"John B." wrote in message
...
On Sat, 16 Sep 2017 13:30:10 -0700 (PDT), wrote:

On Friday, September 15, 2017 at 7:30:42 PM UTC-7, John B. wrote:
On Fri, 15 Sep 2017 19:59:27 +0100, "Ian Field"
wrote:



"John B." wrote in message
.. .
On Thu, 14 Sep 2017 21:33:17 +0100, "Ian Field"
wrote:



"Joerg" wrote in message
...
On 2017-09-14 10:42, AMuzi wrote:
On 9/14/2017 12:32 PM, Ian Field wrote:
The bike I built up on a frame I dragged out of a hedge has
a seized seat post.

So far; I've slackened the clamp bolt and give it a squirt
of PTFE penetrating oil at least once a day - is there a
reasonable expectation that it might work loose?

Thanks.

Yes.
The vibration and cyclic loading of the post can free them.
Not always but well worth a daily shot of penetrant and some
miles.
Leave the bolt out and cross your fingers!


Might sing soprano after it let go all of a sudden :-)

Its seriously stuck, it'll probably need a lot of twisting to shift
it at
all once it starts to loosen.

If I still had a welder, I'd weld a lever arm to it so I could apply
enough
force.

If it is an aluminum seat post in a steel frame and you can't budge
it
with a, oh say 24 inch pipe wrench, after a few days of penetrating
oil then it probably won't come out without some serious attention.

I once spent nearly a week to make a boring bar and boring out a
stuck
seat tube after all else failed however after reading the Internet I
discovered that dissolving the aluminum tube using lye would have
been
much easier :-)

No aluminium - and I wouldn't want a glob of corrosive **** running
down
into the BB bracket if there was.

You are supposed to disassemble the bicycle before you start :-(

From the Internet:

As a strong alkali, sodium hydroxide will attack and dissolve the
following metals: Tin, Aluminum, zinc, cadmium - behaves closely
enough to zinc. It will also attack chromium plating and copper,
although ammonia is far better at dissolving copper:

The reaction with those metals releases hydrogen gas.

Sodium hydroxide will not react with iron or steel, in fact the
alkaline conditions will not allow rust to grow;

What would you use in a frame that has been fully chromed?

Well, not lye :-)

Sheldon writes that "Fortunately, aluminum oxide can be dissolved like
magic by using ammonia" however Brandt disagreed :-)

I have no idea whether ammonia attacks chromium and "chrome plating"

Ammonia is common in cleaning products - I've never noticed any problem
using it on chrome plated fittings.

I used to clean E-cigarette wicks by soaking in ammonia, the housing is
stainless steel - there were no visible signs of corrosion.