These guys reckon Glyptal is good, so long as you bake it.
http://www.coultersmithing.com/OldStuff/piranigage.html

Also, that metal gasket really just needs to be soft metal without any pores. Could try moulding your own out of solder?

I’m not certain that solder would be all that good – may have too much dissolved gasses in it, but it’s certainly soft, cheap, and reusable as well.

Best of luck.

This metal coating acts as an electrode to attract the electrons towards it’s centre, and as it’s wrapped around the tube, they fly through the middle.

The vacuum chamber won’t work in this manner – as it forms a faraday cage when seen from the inside. If the cathode is at large negative volts with respect to the vacuum chamber, the electrons will just take the shortest path directly to it, not forming a beam at all.

Point is, to throw the beam across the chamber, you’ll need a ring shape in front of the gun, at a high positive voltage with respect to both the gun and the vacuum chamber, in order to attract the electrons towards it.

You don’t necessarily need much voltage between the focussing ring and the cathode – it’s really intended just to change the width of the beam, acting as an electrostatic lens – hence it will need to be negative.

You also don’t necessarily need much negative voltage on the gun itself – probably enough to overcome the work function of the cathode surface.

When you run a CRT externally, you can get away with wiring the gun to high negative, and the ht connection around the screen to ground, and it’ll work, because the screen is still the closest “positive” to the gun. But in the vacuum chamber this won’t work until the gun is pointed at the nearest wall of the chamber.

As always, best of luck, mate.

(this is very expensive)

The sealing method basically depends on the copper deforming as the edge cuts into it, creating a seal that’s basically perfect. This is also used in some very high pressure seals.

I suggest use of a torque wrench, and some experiments to determine how much torque you need to get good vacuum on the first, second … n times that gasket is used.

You’ll probably find you need to do it up a little tighter each time, as the copper deforms and exposes more surface area for the edge to contact.

At least this way you’ll be able to get the maximum reuses out of your copper gaskets.

I’d also be tempted to try with Al-foil or Al-sheet gaskets as well – it’s sometimes used in place of copper (which has been in use for this kind of deforming seal for a very long time).

Might be worthwhile making up a set of dies to cut your own gaskets – it’ll allow you to make your own gaskets and not pay the “research tax” these lab parts otherwise seem to attract.

Best of luck

Might be useful to loosen up one of those nuts and use the stethoscope to listen for the related leak when you know roughly where it should be, just to practice.