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loose tube bases - Tubesforme - 03-23-2017

I am not sure where this should be posted. While it isn't a critical issue, I recently had a long discussion with a fellow restorer regarding gluing loose tube bases or top caps back on and I would like to hear what others use. I used to use radio service cement, however that was a real pain and could be messy. I also had tried the Elmers glue for all materials. However many year ago I started by cleaning around the base, with a damp rag, letting it dry thoroughly and then putting a few drops of super glue around the base. It always settles down between the globe and the base and quickly sets up. I have never had any problems using this method and have done it for years. However the fellow I was discussing this with went on to tell me I should only be using the Elmers glue. He couldn't remember where he heard it, but told me he had heard that using super glue is dangerous and that it can't take the heat and the joint should be able to have some give. Any Ideas? Thanks guys

RE: loose tube bases - Mondial - 03-23-2017

I have also used super glue on bases and top caps for many years without problems. It wicks into the space between the glass and base and is easy to clean up the excess with alcohol or lacquer thinner.

Don't think Elmer's is really a good choice, as it does not adhere to glass well and is water soluble.

RE: loose tube bases - Steve Davis - 03-23-2017

I think where you get in trouble with super glue, is if you use it on tubes that operate at a high temperature, such as rectifiers and output tubes. From what I understand, the bakelite base and the glass, expand and contract at a different rate. Super glue is very strong and has no give and will cause the glass to crack.

Steve

RE: loose tube bases - Jim Koehler - 03-23-2017

Mondial posts.....

"Don't think Elmer's is really a good choice, as it does not adhere to glass well and is water soluble."

If you're going swimming with the radio, yes, Elmer's is a poor choice.

However......

How you prepare the grid cap is also a very real concern. Hopefully, you have enough grid wire to re-attach it to the grid cap. That being ascertained, I'd take the Elmer's and fill it to the brim of the grid cap. Wait for it to set and flip it over on the grid wire and look until the grid wire was poking through the hole. Take my soldering iron and heat up the cap (and watch the Elmer's boil) add a little solder to the cap....and wait.

It becomes a good bond to glass and whatever's in the cap.

...Jim

RE: loose tube bases - Arran - 03-23-2017

I like to use Permatex windshield adhesive and sealer, it works good on grid caps, and to re attach a tube base, as for fixing a loose one I have not tried that yet without removing the base first. I often do this with the tubes with the old style bases since the solder joint on the pins are often bad as well, like on a #24As, #45, #47s, #26s. Without taking the base off I think that I would go the epoxy route.
 I learned about this substance from our own Bob Andersen, but unlike Bob I bought the black rather then the clear kind. By the way, I also used it to glue some new tube sockets in place so they wouldn't spin, they were the molded Bakelite type with a wavy clip ring, and are supposed to go in a keyed hole to stop them from rotating, which this Electrohome chassis did not have, the Permatex did the trick.
Regards
Arran

RE: loose tube bases - mark123 - 03-24-2017

(03-23-2017, 08:58 PM)Jim Koehler Wrote:  ...I'd take the Elmer's and fill it to the brim of the grid cap. Wait for it to set and flip it over on the grid wire and look until the grid wire was poking through the hole. Take my soldering iron and heat up the cap (and watch the Elmer's boil) add a little solder to the cap....and wait.

Hi Jim -
I like your approach, but I'm a little confused.

You say: "take the Elmer's and fill it to the brim of the grid cap". Should I do this without digging the old stuff out of the grid cap, or dig the old stuff out of the grid cap first? Seems like the grid cap wouldn't hold much Elmer's if you didn't dig the old stuff out first.

You say: "wait for the Elmer's to set and flip it over...". By "set" do you mean completely dry and rock hard, just skinned over, or somewhere in between?

You say: "look until the grid wire was poking through the hole". Look at what? Through what hole? Do you mean make sure the grid wire is inserted into its original hole in the stuff packed in the grid cap?

You say: "...add a little solder to the cap...and wait" Where should I add the solder? At the grid cap/tube glass junction? What is the purpose of this? Is it to solder the remaining grid wire to the grid cap? If so, shouldn't you flip the tube upside down so the tube is above (and somehow resting on) the grid cap and so the solder can wick around the remaining grid wire with the help of gravity? And finally wait for what? The assembly to cool?

RE: loose tube bases - NostalgiaRadioTime - 03-24-2017

joernone on YouTube (otherwise known as John from Conway, Arkansas) on his series of restoration videos for his 1936 model 630B recommended this version of Super Glue for repairing tubes with loose bases because it dries clear and is virtually undetectable. Now he only used this for gluing around the tube base to the glass, not for grid caps: http://www.supergluecorp.com/?q=super-glue/job-specific/dries-clear-glass-adhesive

RE: loose tube bases - Arran - 03-25-2017

I don't know if it will actually cause the glass to crack on a hot running tube, but one problem cyanoacrylate glues like superglue, crazyglue, and other brands have is that it tends to crystallize after a time and comes apart, and it doesn't like heat. Epoxy may or may not like heat either, depending on the type, but it doesn't tend to break down with age. The Permatex is somewhat heat resistant, and it's made for bonding glass to metal, so I think that it would be preferable for grid caps for sure, though I have used epoxy for this in the past as well. If you have to take the base off of a tube to resolder pins, such as with a 01A/201A, or a #26, or a #45, then I've found it works well to re-cement the base onto a glass tube, after you've cleaned out the old putty with lacquer thinner of course.
Regards
Arran

RE: loose tube bases - Tubesforme - 03-26-2017

(03-23-2017, 04:35 PM)Mondial Wrote:  I have also used super glue on bases and top caps for many years without problems. It wicks into the space between the glass and base and is easy to clean up the excess with alcohol or lacquer thinner.

Don't think Elmer's is really a good choice, as it does not adhere to glass well and is water soluble.

I have never had a problem with super glue. I have only used it on two top caps. In both cases the wire was long enough, but the cap was loose from the glass and the solder connection was loose. I put the super glue inside of the cap and then seated it on the glass, when hard resolderd the wire to the cap. Didn't have any problems. I also don't run it all around the tube base, I place drops in about four or six places, depending on base size. I have also used it on older tubes where I had to resolder tube pins and never had a problem with it. I used to try epoxy, the clear one, but usually always ended up with a mess.

RE: loose tube bases - codefox1 - 05-13-2017

Agree Elmer's is a good choice. I ususlly put the glued up tube upside down in a coffe tin atop the oil burner and let it dry out for a few days. Especially important on power/hotrunning tubes. Then clean off any dribble on theglass with a razor blade.

RE: loose tube bases - Ron Ramirez - 05-13-2017

I have had good luck with super glue on grid caps, but it will cause the glass to crack at the base if used on the base of an audio output or rectifier tube...any tube that runs very hot.

If a tube base were to come completely off, I think I would try some Sauereisen cement. It is used to hold burner collars and fill cap collars on glass Aladdin lamps. Now there is a good example of unequal/uneven heating. The upper parts of the burners (chiefly where the flame is) reach 1000+ degrees while the glass font remains basically cool.

RE: loose tube bases - Oldresistor47 - 05-30-2017

Superglue is used by crime labs to develope fingerprints on different type surfaces, including off of bodies. They heat the glue which create fumes that lodge onto the prints. Because tubes do heat and it potentially emit a noxious fume. Now being that a small amount is used on a base of a tube, it might not be enough to cause a dangerous situation. I stay away from it.