[Heathkit] TUBE CEMENT??

[km1h]

Ive used Furnace Cement for decades to reattach plate/grid caps as well as 
tube bases. It works best when you remove all or most of the original.
I clean the glass with lacquer thinner.

One product I intend to try is JB Weld. Wondering if anyone has experience 
with it?

Carl
KM1H




----- Original Message ----- 
From: "Tom NØJMY - AAR7FV" <tfarl at mchsi.com>
To: "Murray Grandy" <mgrandy at telus.net>; "HEATHKIT LIST" 
<heathkit at mailman.qth.net>
Sent: Tuesday, January 11, 2005 12:59 AM
Subject: Re: [Heathkit] TUBE CEMENT??


> Well, as long as the glue question came up...this is what I got from Mark, 
> W1EOF, who in turn, got it from Lud Sibley:
>
> "The usual base cement was "No. 6," AKA "C6."  The official recipe for 
> this
> was:
>
> D3 Durite 7.5 lb.
> S15 Shellac    19.5 lb.
> R3 Rosin  3.25 lb.
> M3 Marble flour     170.0 lb.
> A4 Alcohol     9.0 l.
> M19 Malachite green 10.0 g.
>
> Makes 200 lb., or enough to base 23,500 Type 50s at 0.0085 lb. each. Basic
> recipe is in Standardizing Notice 34C-C-6 ("Confidential") of 12-29-48. 
> No.
> 6 was used in transmitting tubes too:  814s, 860s, etc., and CRTs (7BP7,
> etc.).  The bills of material for "modern" tubes (post-'30s) didn't 
> specify
> the type of cement, but I've seen no sign of a change up to the end.
>
> The "Durite" was Durite Resin #275, from Stokes & Smith of Philadelphia, 
> not
> further defined, bought in 50-lb. pails.
>
> The curing process required a cement temperature of about 150øC.  (This, 
> vs.
> the blistering temperature of bakelite at about 190øC.)  The heating
> schedule varied:
>
> CRTs:  heat 10 min. cool 1.5 min.
> 813s:  heat 3-« min., cool 1-1/3 min.
> 8025s:  heat 5-« min., cool 1-« min.
>
> The color change in the malachite was considered only a rough indicator of
> temperature; it was backed-up with a thermocouple thermometer.
>
> There was a slightly modified cement for top caps, with the same 
> ingredients
> but using fine and coarse marble flour.
>
> For use in very large tubes like 207s, where excess heat might crack the
> seals, there was a low-temperature cement.  It was made of "BR-51 
> Resinoid"
> (bought commercially), acetone, and marble flour.  It was for only purely
> cylindrical seals, and cured at 50øC."
>
> Whew!  Aren't you glad you asked?  Personally, I use a tiny amount of 
> "Gorilla Glue" (tradename) available at most any hardware store.  Never a 
> failure yet.
>
> 73,
> Tom
>
>
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