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