Hi SquirrelBoy,
I will endeavour to answer your many questions.
See 10 photos on my PhotoBucket site of the gun rebuilding process taken by RACS, showing a gun at various steps of reconstruction:
http://s281.photobucket.com/user/jha...?sort=4&page=1
If interested to see the rest, the root directory of the entire CRT rebuild process is here:
http://s281.photobucket.com/user/jha...?sort=4&page=1
Obviously much more data is required. I will ask, but it will take time.
When at RACS, i saw an assortment of measuring tools, calipers, gauges, palmers,... sorry, i don't have too much vocabulary in describing tools for mechanical measuring.
What is taken apart: depends on the gun. With modern guns, often the beam focus electron lens and G2/G3/G4 anodes can be left alone because the cathode & G1 are mechanically separate and can be reached.
With older CRTs, for instance pre-War & early color tubes, the cathode & G1 are very close or sometimes even totally hidden inside the anode structure so dismantling of the entire gun is necessary.
In this case, the anodes & metal prongs used to mount them are carefully set aside to rebuild the gun in the precise same order once the filament and cathodes have been replaced with new ones.
I do not know how the glass bars are made originally. RACS does not make them, they re-use the originals with painstaking efforts not to break them.
In their parts inventory they have NOS glass bars and if one is broken, they find a substitute which matches in length, diameter and metal inserts. There is some leeway here, the metal inserts can be to some extent bent or tweaked to match the original, after all the glass bars are only for support and do not play an active role in the electron beam's creation.
Taking the gun apart and rebuilding it is achieved by using a small electric spot-welder with various size tips used depending on the size/weight of the electrode to be welded.
PS: Bob G. took photos and described his experience in removing the cathodes on 15GP22 CRTs. Bob, wanna pitch in?
François R. is justly proud of his engineering skills and describes gun rebuilding as a mix of science, technology, known to work recipes and a pinch of witchcraft. He quoted 16 to 20 man/hours of work to rebuild a 15G tricolor gun. He describes the 3D maze of wires connecting the 3 guns to the base as "an utter nightmare" to avoid accidental shorts when mounting the rebuilt gun to its new base/stem assembly.
Best Regards
jhalphen
Paris/France