[TowerTalk] bolt holes

[Tom Rauch]

> My Rohn 45 sections have two holes in each leg, one large 
> and one small. Why is that? Should I get bolts for the 
> smaller, the larger, or both? Thanks.


They have two bolt holes because it spreads the load out. If 
you only use one bolt per leg the holes will elongate and 
the joint be loose. Use both bolts.

You need to get a good quality bolt of the proper size. 
Since the bolt is in sheer and bolt tension isn't an issue, 
you really just want a bolt significantly harder than the 
tower leg.  I use a high grade stainless steel bolt rather 
than buying the bolt kits. They are just as hard and won't 
rust. We just ordered a bunch from McMaster Carr. Under $50 
to do a 240 foot tower.

If you are bolting together pads that put the bolt in 
tension then you have to worry about tension ratings. Those 
bolts are usually torqued and must have the correct strength 
and stretch, like head bolts on an engine. I wouldn't 
substitute bolts on a 65G, but I don't worry at all with 
something like 45 where the bolt isn't under any tension and 
is only subjected to shearing forces.