johnsmachines

Drilled previously, with wooden plug to prevent boiler deformation

Bushes made, but one is a bit tight, so using the Dremel to make it a loose fit, in preparation for silver brazing.

That is about right.  Roughly 3-5 thou gap.

The middle bush and the right hand one are additions to the Trevithick concept.  The middle one is a banjo fitting which will eventually connect to a modern pressure gauge… a boiler inspector requirement.   The big one is a water filler point.

All plugged up, ready for silver brazing then a boiler inspector hydrostatic test.  The thread which is visible is blind.  It does not communicate with the boiler cavity.