Maintenance checkup prevents disaster

[Janne]

While checking out the guy wires on the 3.2m axial flux generator I found out this:

One of the shackles holding the guy wires had loosened up and almost completely threaded out. I do remember tightening them all up properly, but I guess that the nature of these shackles is that they tend to loosen up under variable load conditions. That is, because only the U-section is providing pre-tension on the threads, and I think it's not enough to hold it. If you use enough force, that the solid part of the bolt jams into the female threading, it seems to help some, but seems like it's not completely secure either.

To prevent this happening again, I've added thread locking compound to 3 of the guy wires, that normally don't have to be taken apart when lowering or raising the tower.  To the one that needs to come off when raising or lowering the tower, I added a safety wire to prevent it completely threading off.

Something for everyone to consider, that are using this kind of shackles in their tower rigging.

[chainsaw]

I would suggest using stainless safety wire through all shackles that are under a load. When applied correctly the shackle bolt will never move and it's  a simple matter to snip with wire cutters when needed to disassemble.

I would never trust thread lok to secure a working shackle.

[DanG]

Preventative "periodic inspection and maintenance", looking at the 'big picture' saves a lot of grief, GOOD FIND Janne!

For that the safety wire does not have to be stainless steel - a Galvanized strand of the wire rope guy cable (heated & cooled to make it workable) or a chunk of Hog fence wire or any new iron wire will check any motion for many, many years. (But keep an eye on it)

The cats had me up way early this morning so I played with photoshop a bit...

[windspeed]

I use a similar shackle but it has the pin going through with a sprung split pin locking the other end.. very handy just pull out the split pin to release

maybe i am wrong but it looks like the anchors are not pointing towards the tower

Windspeed

[Janne]

The anchor is perpendicular to the guy wire(actually about 100 degrees), it's a 16mm bar drilled 200mm into bedrock. This way the forces on the tower can newer pull the bar out from the bedrock.

[la7qz]

Hi

On a boat it is a matter of course that every shackle should be moused whether it's used for standing or running rigging or anchor tackle. Loosing a mast overboard at sea is no fun at all. Nor is loosing your anchor on a lee shore in a rising gale...

SS wire can be used as suggested, but more often a sailor would use whipping twine. It doesn't have to be very strong as it's just preventing the pin from turning, but it does have to stand up to the elements.

Owen

[Ungrounded Lightning Rod]

You use stainless steel wire to keep galvanic corrosion from eating away the thin wire, leaving you back where you started.

The hole is specifically for that wire.

As a guy wire works the shackle against the eyebolt, every sway of the mast or guy wire back-and-forth puts a tiny twist on the shackle bolt.  They don't quite cancel out.  This is why the shackle bolts unscrew, even if you tightened 'em up solidly, and why a mousing wire is necessary.  (Works the same way on an anchor or rigging, too.)

[la7qz]

Hi

Whipping twine doesn't corrode, or catch unwary fingers and dissimilar metals are to be avoided in the marine environment. SS wire is only used on SS shackles. I would never use galvanised wire for mousing a shackle on a boat.

Owen

[phil b]

Twine may work on a boat. The rats and mice on my place would think 'lunch is served'.

[zeebag]

Wow, that would suck if it would fall. Luckily, you noticed it. Though I think that safety wire is a bit unnecessary.

[la7qz]

These days it's synthetic. Not nice for mice.

Owen

[wooferhound]

Safety IS necessary if you don't want your tower to fall on your house leaving you with a busted house without power.  

[ghurd]

At least this is just a teeny-tiny little ten & a half footer only 46' up.

Maybe Janne's 29' up in the air 112' would justify 1/10 of $1 worth of saftey wire?

(Again Janne... Damn that's big.  Frightening to think of what you are making next!)

To save searching, the 10.5' is here,

http://www.fieldlines.com/story/2008/2/1/165448/3101

G-

[Janne]

Hmmm, might consider recommissioning the 40' blade set...