repairing broken tube keyways

[Randall]

I lost a keyway on a 60s RCA blackplate 6V6 today, ouch! But I find clear Gorilla glue to be working quite well at re-attaching it. I had good success not long ago with a vintage 5U4 as well. I carefully dab some on the broken off tab, and very lightly apply a slight wetness to the tube base with a toothpick dipped in water. Squeeze them in place for a minute or so and then carefully prop the tube upside down for 2 hours ( I use a couple of rolls of electrical tape). Next day it seems pretty solid. Maybe not as good as new, but certainly enough to get it inserted correctly in the socket. Good stuff that Gorilla Glue.

[Enzo]

Are you aware of this product? They have made them as long as I can remember, I mean even 60 years ago.

https://www.tubesandmore.com/product...ce-octal-tubes

[christarak]

Are you aware of this product? They have made them as long as I can remember, I mean even 60 years ago.

https://www.tubesandmore.com/product...ce-octal-tubes

Bloody brilliant! Thanks Enzo. I didn't know that existed. I have a nice old KT66 that will soon wear this prosthesis.

[mozz]

Viva tubes has them cheaper.

[christarak]

Viva tubes has them cheaper.

Thanks Mozz. I haven't come across Viva until now. It looks like a very interesting place. I hope he ships to Australia. Who do you recommend for modern production parts (incl tubes & caps). I have been using CE Dist this year, but their shipping costs are quite high and their TungSol & Mullard tubes are the same as what I can get in Sydney...and that can't be right.

[Chuck H]

It's a handy product to be sure. But when I still have the keyway I usually epoxy it back on with a decent two hour epoxy from the hardware store. The five minute stuff can soften with too much heat. I sort of remember trying CA glue once and not being pleased with the result, but I'm not certain.

[Randall]

"Are you aware of this product? They have made them as long as I can remember, I mean even 60 years ago."

yes I have some of those as well

[Rhodesplyr]

I sort of remember trying CA glue once and not being pleased with the result, but I'm not certain.

With CA glue, you pretty much have to use an activator. You can find it sold in something similar to a magic marker along with some CA glues for use on plastic. You treat both edges with the activator, wait 60 seconds, and then glue. Same thing for broken Leslie horns.

[mozz]

Crazy glue, thinner is better, nowhere near 60 seconds. Water is a activator, you don't get many seconds, the glued area will turn whitish color.

[christarak]

Crazy glue, thinner is better, nowhere near 60 seconds. Water is a activator.

I don't think we have the crazy glue trademark here. Whn I see water activated, I'm think it may be a polyurethane glue. Does crazy glue bubble and expand a bit?

[Enzo]

Crazy Glue is a brand of CA.

CA glues do come in types. A serious hobby shop or online hobby supplier should have a selection. There are the ones that bond in a few seconds, then there are the slow curing ones that give you some time to reposition something. I never used them, but there are also formulas that you can use in places where there are gaps.

[christarak]

Aha! We have a good range of CA glues here with different names. It was the water activation that stumped me. Thanks Enzo

[minim]

I don't think we have the crazy glue trademark here. Whn I see water activated, I'm think it may be a polyurethane glue. Does crazy glue bubble and expand a bit?

Chris,

Moved to the US not so long ago and have tried Krazy Glue. It's what we know as Super Glue.

https://en.m.wikipedia.org/wiki/Cyanoacrylate

Edit: We must have simulpost

[Helmholtz]

CA or Super Glues typically have a maximum operating temperature of 80-120°C, which may not be enough for (power) tube bases. I'd go with 200°C epoxy.

[galaxiex]

Aha! We have a good range of CA glues here with different names. It was the water activation that stumped me. Thanks Enzo

Water will activate CA glue, as will baking soda, plus there are "kicker" solvents that activate it.

I've used CA glue extensively in R/C model airplane building.
Many different kinds/brands, thin, medium, thick, gap filling,etc.
Thin sets fast, thicker sets slower, usually needs activator.

Somewhat new to the market is Q-Bond.
Basically CA glue with a "welding powder".
Works good, sets fast, but very hard (as most CA glues) and can be brittle.

https://www.amazon.ca/Q-Bond-QB2-Q-B.../dp/B00HX704NG