[TowerTalk] Ground rod connection: Cadweld or ????

[Kelly Johnson]

When I talked to Joel at The RF Connection about Cadweld one shots
about 2 months ago he told me that the "old style" one shots has been
discontinued and replaced with a "new style" which needs to be ignited
with a very expensive igniter from Cadweld (like $150 or $250 or
something like that).  I don't know if this has changed, but ...
that's going to stop a lot of hams from going the Cadweld route if
something isn't done about it.


On 4/24/06, ersmar at comcast.net <ersmar at comcast.net> wrote:
> TT:
>
>     Additional comments embedded below.
>
> 73 de
> Gene Smar  AD3F
>
>
>  -------------- Original message ----------------------
> From: "Kelly Taylor" <ve4xt at mts.net>
> > Hi Bob,
> >
> > Cadwelding, once you know some of the tricks, is dead simple.
> >
> > Key things to remember are:
> >
> > 1. Matches or other simple flames will not ignite the material. It's
> > deliberately designed such so that the material is less volatile for
> > shipping and storage. The sparker RFC sells is designed to cast sparks
> > forward, as opposed to down, such as with a propane torch spark ignitor.
>
> Available from RFC for less than $8.
>
> >
> > 2. Grind/cut off mushrooming: when the thing says it fits 5/8-inch rod,
> > that's ALL it fits. The bits spread out by pounding the rod will prevent the
> > form from sliding on.
>
> To protect the tops of my ground rods from mushrooming, I constructed my own drive sleeve out of four inches or so of 1 inch iron pipe and a pipe cap.  I put this thing over the ground rod and pounded the ---- out of it with almost no damage to the top of the rod.  I needed two of these sleeves for twelve ground rods.  (I put a piece of electrical tape around the rod where it protruded out of the sleeve to protect the copper cladding from damage from the bottom of the sleeve while pounding.)
>
> >
> > 3. Secure the wires from movement: the combustion process can exert some
> > force on the wire, causing it to be ejected from the form. End result,
> > useless weld. Doesn't need to be much: a brick a foot or so away from the
> > form preventing the wire from moving is all it would need. The force is
> > enough a free wire can be cast out, but not so big as to bend the wire.
>
> My first Cadweld attempt failed because the molten shot leaked out the bottom of the ceramic mold.  I cut off the bad weld and tried again, this time sealing the bottom and side openings with electrician's putty (Home Despot).  Never had a failure in the remaining welds.
>
> >
> > 4. The risk, if there is any, is similar to lighting a barbecue. Don't put
> > your head over the form and you'll be fine. It's not like you're lighting
> > fireworks and need to retreat quickly. The ones I did had maybe 3 inches of
> > flame, and it took a second or two to build to that anyway.
>
> But it IS smokey!  Stay upwind of the shot while you ignite it.  (Very disappointing that there was so little noise and flame.)
>
> >
> > 5. Expensive? About $8, as I recall. A ground clamp is about $3, no? So for
> > an extra $5 you get a maintenance-free connection for life. Not a bad deal.
>
> My ground system (rods, wire, Cadwelds, tower leg clamps, etc.) cost me about $500.  The extra $5X12=$60 for the Cadwelds was a small price to pay for reliable, trouble-free ground connections.
>
>
> >
> > 73, kelly
> > ve4xt
> >
> >
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