clare at snyder dot ontario dot canada wrote:
On Wed, 19 Mar 2008 21:04:46 -0400, John
wrote:

Does anybody still do the old technique of drilling holes before tacking
tubes together to interconnect them for oiling the fuse when it's
finished? I've been told that's not done any more, because of the
realization that as long as the welds are air tight, the oxygen trapped
in the tube is consumed in a small amount of oxydation of the metal
surface inside until all that's left is nitrogen and then it's fine
without any oil inside.

Comments?

John
We drilled ours.
If you are 100% confident all your welds are perfectly air-tight the
oxygen arguement is true. Some guys stuff washed steel wool into the
tube as a sacrificial element.

We are thinking of putting a guage and valve on ours to see if it IS
airtight and possibly argon fill it.


Aerospatial Llama helicopters do that. Dry nitrogen would be fine.

Or, use a vacuum pump and evacuate the truss, with a vacuum gauge to
monitor it.

John