Towertalk
[Top] [All Lists]

Re: [TowerTalk] Cadweld Question

To: "Mark Robinson" <markrob@mindspring.com>,"Tower" <towertalk@contesting.com>
Subject: Re: [TowerTalk] Cadweld Question
From: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
Date: Tue, 31 Jul 2007 17:59:40 -0400
List-post: <mailto:towertalk@contesting.com>



>I was looking at the Cadweld procedure and was wondering if it is possible
> to use my oxy-acetylene torch to heat up the cadweld material instead of
> messing with pyrotechnic chemicals.

That's the nice thing about CadWeld (TM). They are neat, easy, and clean. 
They are safe to store and safe to use when the directions are followed.

>
> What is the base material that they use to join the rod and copper wire?
> Maybe I could just braze them together using a brass filler rod.. Any
> thoughts on this?
>
I have on occasion brazed cable to ground rods, but it  takes a lot more 
skill than CadWelding. I'd pick CadWeld any day over brazing.  Unless you 
have plenty of experience with a torch I'd stick with the CadWeld.

For brazing the cable needs to be absolutely clean with solid copper being 
much easier than even coarse stranded. With coarse stranded you first need 
to fill the stranded cable with the brass to a bit either side of where the 
joint will be made.  Then heat the top of the ground rod and apply enough 
brazing rod to completely coat the top.  Then the brass filled cable. Use 
lots of flux and get the brazing rod in as early as possible. Due to the 
thermal conductivity of the copper it's not unusual to see most of the brass 
*fall* out of the cable just as it starts to bond to the ground rod.
At this point it is very easy to burn the copper which makes refilling 
almost impossible.  In addition you need to have the proper size tip on the 
torch for the size cable and ground rod.  Being different material the 
ground rod and cable heat at different rates, different thermal 
transmission, and different melting points. The copper, due to the thermal 
tranmission characteristics takes more heat, but it also melts far easier 
than the steel. In addition the melting point of copper is not all that far 
from brass, relatively speaking. So, you end up trying to braze the brass 
filled copper to the steel ground rod without melting the brazing out of the 
copper in the process.

With solid copper, using lots of flux, heat and wet the cable with the 
brazing material. Wet the top of the ground rod in the same manner, then 
with a bit of practice join the two brass covered surfaces and fill any gaps 
with brazing rod.


Good Luck,

Roger (K8RI)
>

> 73's de Mark N1UK G3ZZM
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk 

_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

<Prev in Thread] Current Thread [Next in Thread>