I am hoping to use carbon fibre composite tube for the pendulum of a precision regulator clock.  I believe that the coefficient of thermal expansion of pulltruded carbon fibre composite is somewhere between 0.1 and 0.3 ppm /°C but wonder if you can give a more exact figure  for your tubes so that I can design a compensator.

Thanks in advance.

Edit:  The coefficient is I believe negative.

I'm still hoping for a definitive answer from a staff member.  I guess that your tubes are bought in from an American company or a far eastern one as the published specs refer to ASTM standards rather than BS or EN so I understand if it takes a while to get the information.

Doing further research on the internet I have found specifications quoted from - 0.3 to +8 ppm/C in the direction of the fibres.  This strikes be as a very wide range.  I would like to get my completed pendulum length to within plus or minus about 0.2 with compensation if necessary.

TIA
Russell.