Repairing Top Cap on Tube

I bought a 1939 GE portable with 4 1 volt tubes one of the had the metal cap off. One friend recomended cleaning the wire and tintiing it and heating the cap to rejoin it. I assume you also want to glue it back in place. Would this a good thing the tube is a 1N5

Tin it solder it.Most glues will not work if the tube gets very hot.Iforget but 1 glue works very good.Try gorrila glue or superglue..Sprman : )

I have read the super glue may break the glass, expansion during heat maybe?

Group
The 1N5 in a battery set doesn't produce any heat when its working, it doesn't glow!!!

Actually you CAN get one volt filament tubes to produce a dim glow.
I've done it in one of my battery sets, by using two D cells wired in parallel, to double the current, and in the dark, they glow, lol.
Of course they don't heat up, so using glue would not be consequential in causing damage.

Some advocate furnace cement for that. A drop of Elmers white would probably hold forever on a battery set tube.

Ok We'll give it a shot of glue. Im bulding a battery eliminator for the b battery and trying 2 Ds for the A.

Gang I did it. Tube tested good after repair. First you tin the wire. Then you super glue the cap to the tube. Next hit the top of the tube with a bit of solder.

As stated, sometimes superglue can cause a tube to crack. The low voltage types ay hold up though as they don't make much heat.

Of other tubes, I have seen where the glass cracks right around the tube cap, in a nice circle. I don't spuerglue any tubes.

Duco Cement works just fine, and you can buy a generous tube of it for a dollar almost anywhere. I've used it for reattaching tube grid caps for over 20 years and have yet to have one give loose or otherwise fail. It is quick drying and cleans up easily with ordinary nail polish remover (acetone). When I was a kid this stuff was known as "airplane glue" owing to its use in constructing model airplanes.

Duco Cement works just fine, and you can buy a generous tube of it for a dollar almost anywhere. I've used it for reattaching tube grid caps for over 20 years and have yet to have one give loose or otherwise fail. It is quick drying and cleans up easily with ordinary nail polish remover (acetone). When I was a kid this stuff was known as "airplane glue" owing to its use in constructing model airplanes.