[TowerTalk] Tower Base Challenge

[Wilson]

“If anyone wants to be serious about this, the formula for the pull-out 
resistance of lag screws is on page 8-10 of this document 
<http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr190/chapter_08.pdf>. 
Compare whatever numbers you get to the ultimate strength of 3/16 EHS 
guy wire, factor in an appropriate safety factor, and I bet you'll 
abandon the idea. “

I read it and I see that even in pine, living or at least not rotting, a thread penetration of 12X shank diameter will break a lag in tension.
Pretty amazing, really!  So a half inch lag should be more than enough for 3/16 wire.  But why depend upon pure tension when you can use a loop and depend only upon the stump?

That said, the through bolt and big washer “looks” a lot better and doesn’t depend much on wood quality.

I don’t advocate using rotting stumps, but if one needs a temporary solution a pine stump is fine for several years, all the more so if you use a loop around it to anchor the wire.  No, I’ve never done it, BUT I regularly butt 6-8” stumps as hard as I dare with my 50HP tractor and it has no effect except to shake me up and scratch the stump a little.  Generally, they can’t be uprooted by that method, but will eventually break off after most of the wood has gone punky.  I think most of them retain lots of strength for at least five years, maybe longer.  No doubt there is some variation among the species,  Some retain a strong heart much longer than others.

WL