--- In ap-gto@..., "nfoldager" <nf@> wrote:

James,

- The steel pipe extends another 42" above the surface of the
observatory floor. This portion is just the 12" steel tube, and

is

the "pier" on which the mount and OTA will be placed.

Did you fill anything into the tube?

As to attaching the mount to the pier, I will be welding a
flat plate to the top of the steel tube.

Are you sure it is wise to weld it instead of bolt it? There is a
danger that the plate will not be flat afterwards.

Best regards,

Niels Foldager

A bowed top plate seems hard to avoid with welding, yet at the same
time realatively easy to remove with a power grinder. Since I'm anal
about this I follow up with a tile tool and Carbo (standard mirror
making tools).

Tom