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.
Ready for silver brazing in a day or two.