Repairing valve bases

[exurbia]

Hello everyone,

I have had to remove the base of my fave 27, as in the photo.

My question is about adhesives, does anyone know if araldite is

suitable for gluing the base back on ?

[Bas Horneman]

Sorry don't know about araldite.

Loose Bases.

To re-cement the tube, use clear nail polish - paint a ring around the base, let the polish soak into the old cement, recoat, and let dry overnight. Polystyrene "coil dope" works as well, and can be used to refill the nail-polish bottle.

Solvent (acetone, etc.) are ineffective in softening the old base cement - the cement was baked hard in manufacture, and "nothing" dissolves it.

"Source : Tube Lore by Ludwell Sibley"

Cheers,
Bas

[jacky]

I used superglue for loose tube base and it seems to work fine.

[Bas Horneman]

Apparently superglue en nail polish are fairly similar :-)

Cheers,
Bas

[EC8010]

Why not solder the valve directly into the circuit, avoiding the leaky valve base, valve socket, one soldered connection and one contact connection?

[jacky]

Originally posted by EC8010
Why not solder the valve directly into the circuit, avoiding the leaky valve base, valve socket, one soldered connection and one contact connection?

Don't think it is a good idea. The base is there to provide support to the glass in addition to allow ease of interchanging tubes.

By the way indeed there are subminiature tubes with leads to be soldered directly to the circuit. But not for bigger tubes.

[Paul Barker]

Though for years I thought it was the thing to do, someone who knows about these things once explained why you should not use superglue; you can end up with cracked glass. I don't remember the exact detail or who it was. Consequently I wouldn't use superglue, I believe a more pliable adhesive is required.

[eeka chu]

I wouldn't use any epoxy based glues, they'll probably melt when it warms up. Or at least soften.

Epoxy sticks things really well, but as it gets warm it starts going very rubbery and eventually turns into a sticky mess. If you've ever tried to sand it you'll know what I mean.

I'm also not so sure about how healthy the fumes from warmed up glue are. Anything that involves Cyanide in it's production kind of scares me...!

[Sch3mat1c]

Actually, epoxies can go hotter. Though off-the-shelf stuff probably isn't good. Cyanoacrylate glues tend NOT to stand temperature, however. I *think* nail polish could work. Rumor has it polyurethane (or generic varnish, whatever) will work.

Can you tell I haven't done this before?

Tim

[exurbia]

Thanks for all the tips on repair, the old cement was the problem

it had fallen apart. In my infinite wisdom i threw it out,

I am going to try silicon rubber as the new cement it is heat

resistant and pours easily. I'll put up some pics if it works.