How do your re-glue a plate cap?

[Todd, KA1KAQ]

I'll look for it, Don. If it's on paper, it's lost temporarily in one of the boxes still awaiting unpacking. I may have it on a backup drive where I stashed a bunch of stuff from previous computers. My recollection is that some of the materials are either no longer available or require a permit or license of some sort.

Fortunately, I left the black hole at the previous location. The radio room here is quite tidy and organized [so far].

[WA3VJB]

I wonder if the furnace cement is basically the same stuff as they used in muffler repair kits years ago? Black and somewhat gritty as I recall.

Holts Muffler Seal !!?!

Man I went through cans of that stuff trying to hold the donut in place under the clamp between the exhaust manifold and the first exhaust pipe on my '66 Austin-Healey.

Only reason it didn't permanently fix the problem is that the pipe was the lowest part of an already low car.  Kept hitting stuff sticking up in the road, like manhole covers.

Holts Muffler Seal had silica in it, was water based, but cured to something so strong you could file it into shape to take the clamp.  I can't find it in a search anymore, but there is a Permatex product that looks like a fairly close match.

Check the data sheet. It's like $8 a squeeze tube.

http://www.permatex.com/documents/tds/automotive/80333.pdf

[KM1H]

Ive been using real old fashioned furnace cement with sodium silicate almost as long as Ive been a ham and it was passed along to me by someone as old as I am now

The brand I have now is Harveys and its in a small 8 Oz container and its still fresh after about 10 years of use; it only cost $1.79 back then but I still see it in stores.

After the cap hole is opened and the plate lead tinned, rough up the shiny surfaces of the old cement inside the cap.  Coat the glass and inside the cap with just enough water to wet. Fill the cap with cement and place the tube upside down and ram it home; hopefully you can still find the hole   Hold the cap tight, place it in a socket, clean the metal tip of cement and solder while keeping down pressure on the cap.

Since its heat curing at least run the filament or put in an oven. Dont put a plate cap on until its fully cured.

From what Ive been told by others it is the closest thing readily available to the original tube cement.

[WBear2GCR]

Like this?

http://www.holtsauto.com/products/print_view/repair-and-maintenance/exhaust-repair/holts-gun-gum-paste

         

                     _-_-bear

[WBear2GCR]

Anyhow, Don, my recollection of the formula was that it required Phenol, and some other chemicals that are somewhat toxic and dangerous to work with. Back when I had a formulation recipe in front of me and considered it, I decided that working with the stuff was likely best done in a proper chemistry lab set up, with a fume hood or not done at all. There may be other formulations that are safer to deal with, or you or others may have far more experience than I do in the chem lab...

                         _-_-bear

[W1ATR]

I just remembered something. Two of the finals in my valiant have the caps held on with rear view mirror glue. I guess I forgot about it since its been about 10 years. I just had the V out of the case for dusting a couple months ago and everything looked good. If the caps were loose I would have noticed it when I wiped them down.

[N2ZD]

  Regular brick mortar will work, ask me how I know...

  Richy N2ZD

[WBear2GCR]

Ok... how?

And, the sand in there is a bit large?

                  _-_-bear

[KA1ZGC]

After the cap hole is opened and the plate lead tinned, rough up the shiny surfaces of the old cement inside the cap.  Coat the glass and inside the cap with just enough water to wet. Fill the cap with cement and place the tube upside down and ram it home; hopefully you can still find the hole   Hold the cap tight, place it in a socket, clean the metal tip of cement and solder while keeping down pressure on the cap.

Since its heat curing at least run the filament or put in an oven. Dont put a plate cap on until its fully cured.

I actually had better luck keeping the tube upright. It was easier to guide the lead into the hole that way. There was no danger of the cement falling out of the cap because I didn't apply any water.

It cured solid within an hour without any heat being applied (apart from a few moments of heat from the soldering iron). Furnace cement air-cures (I have a nice 10-oz. paperwheight with a loose lid as evidence), the heat isn't actually required.

Still, any landing you walk away from is a good landing.

[N2ZD]

Ok... how?

And, the sand in there is a bit large?

                  _-_-bear

 Ok,

  I was using some white mortar to repair some brick work on the fronf of my house. I made the mistake of mixing it in a glass jar. The white mortar is like chalk and it uses white sand which is much finer than regular sand. The mortar hardened to the jar like white on rice. I would be a small amount of crushed white sand and some white mortar will hold the cap on like no tomorrow.

[WBear2GCR]

White portland - white tile grout - white what was it?? White is unusual for brick mortar.

How much force did it take to get the stuff off the glass??

Innertesting...

                   _-_-bear

[KM1H]

It cured solid within an hour without any heat being applied (apart from a few moments of heat from the soldering iron). Furnace cement air-cures (I have a nice 10-oz. paperwheight with a loose lid as evidence), the heat isn't actually required.

Harvey's specifically says to "moisten areas to be joined and allow joint to dry gradually: apply heat slowly until cement hardens."

[KA1ZGC]

It cured solid within an hour without any heat being applied (apart from a few moments of heat from the soldering iron). Furnace cement air-cures (I have a nice 10-oz. paperwheight with a loose lid as evidence), the heat isn't actually required.

Harvey's specifically says to "moisten areas to be joined and allow joint to dry gradually: apply heat slowly until cement hardens."

Hercules says the same thing about patching fireboxes. You always wet bricks before you cement them, or the cement won't bond.

All I'm saying is the stuff will cure without heat and bond to metal and glass without water.

I never said you were in the wrong for using heat and water, I just said it would work equally well without them.

[KM1H]

I doubt the

equally

remark. If the manufacturer includes instructions its usually a smart idea to follow them.....works for me for 50+ years. Do as you wish.

[KA1ZGC]

I doubt the "equally" remark. If the manufacturer includes instructions its usually a smart idea to follow them.....works for me for 50+ years. Do as you wish.

I will, and I did, thank you.

You can doubt whatever you want. Leave the cover off your bucket and tell me what happens. Stick two globs on a tube, one that's been moistened, one that hasn't, and tell me what happens.

Better still, come up to the house some time and I'll show you the tube. I defy you to work that cap loose again. Then you can tell me how wrong I am and how old you are.

[KM1H]

Well sonny boy, as the title of another thread mentions "Is he full of ****?"

Age and experience always trumps a self appointed instant expert.

 

[WBear2GCR]

Thom, I have found that decafe works best for this application. Ymmv?

                        _-_-bear

[W7TFO]

As an update to an older thread, here is a link to the real deal, including RCA's formula for tube base cement:

http://www.antiquewireless.org/otb/vt0108.htm

Get crackin, and drag out your mortar & pestle!

73DG

[Mike/W8BAC]

That's cool Dennis. Thanks for posting!

[W1KSZ]

I believe the stuff the tube manufacturer used was called
Sauereisen Cement. The last I used that stuff was 40+
years ago, so my memory is not 100%.

73, Dick, W1KSZ