Subject: Re: [TowerTalk] Cadweld Question
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>>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?
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Roger wrote:-
> 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.
>
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Maybe I should cut a rod down and practice attaching a short length of
copper wire and see how it goes.
Would wrapping with wire and or clamping and soldering be a better bet than
brass brazing?
Mark N1UK G3ZZM
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