[TowerTalk] Roof tower Glen Martin RT-1832 installation

[Patrick Greenlee]

Bob, You may not have snow but wind is still a consideration. Do yourself 
(and your insurance rates) a favor and through bolt rather than screw. Much 
stronger and longer lasting solution.

If you insist on screwing around then use lag bolts and predrill pilot holes 
the full penetration depth of the lags. To drill  the right size hole  for 
piloting lags use a bit with a diameter equal to the diameter of the body of 
the lag.  The body of the lag is the diameter NOT INCLUDING THE THREADS. 
Oversize the bit and you will reduce the threads holding power. Undersize 
the bit and the taper of the lag will act as a splitting wedge and split the 
wood resulting is very poor holding strength for the threads.  An exception 
is with very soft wood which may not split and will accept slightly 
undersized pilot holes.

That said, please use through bolts if at all possible.  They are a much 
much better solution. Can't be on both sides at once? Tee nuts inside the 
attic will help, These nuts have sharp "spikes" which go into the wood and 
hold the nut against turning.  Once the Tee nuts contact the wood you will 
not have to have a wrench on the inside to hold the nuts as they will hold 
themselves.

With a Tee nut loosely screwed onto the bolt and with you back on the 
outside on the roof you just pry up on the bolt a little while turning it to 
engage the Tee nut's self holding spikes to the wood.  Once they grab then 
you just tighten as if someone were holding the nut with a wrench for you. 
A good alternative to getting a child or small person to safely navigate the 
attic and hold a wrench on the standard nuts.

Tee nuts are available from a plethora of sources including many on the 
internet. They come in steel as well as stainless steel, brass, etc. Just 
search on Tee nut or T nut.

Best of luck to you on your project.

73

Patrick AF5CK

-----Original Message----- 
From: Robert West
Sent: Saturday, August 10, 2013 11:22 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Roof tower Glen Martin RT-1832 installation

I'm about to install my RT-1832. My attic space is tight because it is a web 
truss type roof support. The roof slope is low because there is no snow 
here. I am adding the required 2x6 or 2x8, 8' long attic reinforcing beams.
Can I use screws instead of bolts to mount the tower legs to the 2x8 attic 
support? It will be very difficult to tighten nuts in the attic.
Any tips for aligning the mounting holes? I was thinking of using long nails 
through the roof to mark the tower feet mounting holes before installing the 
attic beams so I can make sure they are centered. I was going to use the 
lower tower section to mark the feet mounting locations by checking for 
level and then using nails to mark locations.
I might follow advice of another tower talk member and use a 32' extension 
ladder extended to maybe 22' and use it as a gin pole lashed to the lower 
tower section and hoist the top section onto the bottom. I would pre-mount 
the rotor and mast. Then the same ladder could be used hoist the beam 
antenna.Bob


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