[TowerTalk] Ground rod connection: Cadweld or ????
ersmar at comcast.net
ersmar at comcast.net
Mon Apr 24 10:26:08 EDT 2006
Additional comments embedded below.
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
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