On 11/17/22 9:51 PM, KD7JYK DM09 wrote:
On 11/17/2022 18:33, Hans Hammarquist via TowerTalk wrote:
I used the same type as the utility companies. They are a lot cheaper
if you buy them from a utility supply house. Anyhow I put them in with
the hep of a sledgehammer and a break-iron. We were two to do it. You
turn the helix anchor as far as you can. then you hit it a few times
with the sledgehammer and continue turning. The idea is that the
screw-anchor should be set in "undisturbed soil" to get maximum strength.
I looked at those when I was buying the utility pole thimble eyes.
My concern was, despite that big elaborate screw, depending on the
model, there was a few tack welds, or one relative short weld around
the shaft to hold it.
Crack that, and the anchor slips out, leaving the screw in the hole,
and tower on the ground.
All the screw in anchors I've seen (several dozen, 30 years ago) had a
continuous weld for the entire helix. I would say that a "tack weld +
short weld" is a unit that was mis-manufactured (i.e. shipped before the
final welds were done). As you say, if the weld were to fail it would
be a problem.
I guess it's possible that as long as the total weld area is sufficient
(greater than the shaft cross section), the screw might deform, but
still stay attached and mostly embedded (the helix pitch might get
longer or it might unscrew a bit (sliding along the helix length), but
that seems unlikely, since the soil is holding it in place. It's all one
piece of metal (if the weld was done properly). A good weld won't be
more brittle than the parent metal.
They do actually test these things - Ask the mfr if that's their
standard practice.
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|