In message <E0zzQOT-0000QX-00@neodymium.btinternet.com>, Bob Fairall
<bob.fairall@btinternet.com> writes
>It is only since December that this problem has occured. While Europa, who
>I must add I hold in the highest esteem, especially for their help and
>advice, indicated this was a problem caused by damp, you can hardly call
>last summer particulary dry!!!! So why did the problem take so long to
>manifest itself? Could it be a combination of damp AND COLD that causes
>this problem?
>
The original bearings contained ptfe which has a very high coefficient
of thermal expansion, but negligible water absorption. I think the
effects you are experiencing are primarily due to the cold. PTFE also
has a poor static coefficient of friction, but a very good coefficient
of dynamic friction. This tends to give "stiction" in bearings; i.e.
they may require a significant force to move and then they move freely.
Regards,
Ken Whiteley
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