[TowerTalk] MonstIR/Orion (mast clamp slipping) problem

Mark . n1lo at hotmail.com
Tue Feb 28 13:10:28 EST 2006

Howdy Steve, et all;

I'll throw out a couple of ideas that might be helpful.

1) Try some anaerobic joint locking compound (threadlock/'Locktite' type 
stuff) between the mast and the clamp. Try the blue/medium grade, which 
should be easily removed for maintenance using a heat gun. The red/permanent 
grade will be stronger, but harder to remove (anyone have practical 
experience removing red grade?).

2) Install a square mast adapter. It's not like the Slippnot, though, but 
requires some custom machining. Fortunately, this can be done in the comfort 
of a shop, before climbing.

The adapter fits on the bottom of the mast to convert it to a square cross 
section. The upper portion would be a light slip fit around the OD of the 
mast for a length of 8-12 inches or so, and would be kerfed on 2 sides, 180 
degrees apart (like a Yagi element joint). The lower portion would have a 
square cross section sized for a secure grip by the mast clamps on the 
  Multiple muffler clamps placed on the outside of the adapter create an 
adjustable friction fit, that could still slip and protect the rotator, if 
desired. Keep adding clamps to add more friction. This approach requires no 
drilling for conversion on the tower!
If you desire the pinning approach, the adapter and mast could be drilled 
for a number of bolts or pins to multiply the torque they can hold before 
shearing. The bolt/pin diameter and metal can be chosen to shear at a 
certain torque that is still higher than what an average windstorm might 
generate, but lower than that which would damage the rotator.

For bolt loosening, I think you are referring to permanent (plastic) 
stretching of the mast clamp bolts. Assuming the mast clamp parts are beefy 
enough, a higher grade and/or larger diameter mast clamp bolt might prevent 
them from loosening by permanent stretching.

Good luck,


Steve asks:

<<Howdy -
     I've installed 2 MonstIRs and they both used the  Orion 2800 rotator 
a pinned mast clamp/mast. In the last windstorm, they  both started turning.
I used an SAE graded bolt for pinning them both and they  both broke. I'm
going to replace the mast pin with a bigger bolt but I'd like to  come up 
with an
additional way to keep it from coming loose.
     Tom, K5RC, has come out with the SlippNot for  Hy-Gain type rotators
that's adds additional holding power to the rotator/mast  connection - sort 
of a
belt-and-suspenders approach. That's the direction I'd  like to head in. 
anyone have any additional suggestions? I'd appreciate  it.
     BTW my experience with M2 Orion rotators is that  over the years, just
about 100% of the mast clamps have eventually loosened up.  After much 
and investigation, I attribute it to bolt stretch;  particularly since 
you do to the nuts (LokTite, double-nutting, etc.)  seems to help.

Cheers, Steve     K7LXC TOWER TECH - Professional tower services for 
Cell: 206-890-4188 >>

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