As we did not have 1" pipe in stock, Aad machined 2 plugs from 30 mm solid bar.
The parts were hollowed out to the same wall thickness as the existing tubes, but
with a stepped end that could slide into the existing frametubes.

 
 

We cut the angles on the tubes with a bandsaw, then used belt sander and a small
pneumatic sander to cope the ends so they would fit nicely, and then Aad started
TIG-welding it all together. We think the lines of the frame are looking a lot
better than when we started! To be continued..