There it is with the view ports welded in. I went for one to view filament and on to view object being coated. (I didn't do the welding, I thought, as it was critical I leave it to the expert!)
There was some distortion when the welding happened so I had to sand the flanges flat again. I made that little sanding thing to help. It took a while but I got then flat enough for the o-rings to take up any of the remaining irregularity.
The strangest thing was the bottom of the jar was no longer flat after the welding process. It shrank upwards towards the welded pipe. I was very surprised. It was across a section of at least 50mm. I spotted it when I did a test pump down and the bottom gasket was buzzing as air rushed in through the gap! Back to the counter top with sand paper as described before.
Above is a view of the o-ring seal on view port. The o-ring are viton(€16 each woops). 6mm cross section. The glass is a square in 12mm, normal type. I just got a glazier to cut it for me.
So the tube sits proud of the flange by about 3mm. This keeps the o-ring in place. I cut the clamping rings from 3mm aluminium. Drilled the top one tapped the underside one. It is split as you can see from the side view.
Oh and I pumped it down today, its tight! Yipee!
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