[TowerTalk] split locks vs star washers

[Tom Rauch]

>  For the shield connections, I used split lockwashers under each nut.  I
>  just tried replacing one of them with a star washer, and my impression is
>  that it "grabbed" much more positively.  Is this generally the case, and
>  are star washers preferred for conductive connections?
> 
>  73, Pete Smith N4ZR
>   >>
> I've found SS split washers virtually useless.  The bolts virtually all
> loosened on my tower.  I now use Elastic Stop Nuts.  k7gco 

Split washers work well in lower tension applications where 
materials are hard but have "give and take". They take up the slack 
as required, and don't sink into the material (if it is the correct 
harness).

Star washers have less compression, but apply more pressure. 
They sink into the surface, and also collapse a bit. They are for 
hard surfaces that don't expand or collapse much.

Conical washers are like high pressure split washers. They have 
high pressure and don't dig in.

What most people miss about bolts is they only actually "lock" 
when something elastic stretches and/or compresses. For 
example, the lug nuts on your car stay in place because the nut 
actually distorts and keeps tension on the wheel all the time.

Rod bolts on connecting rods are designed to "stretch", and that 
keeps the connecting rod caps seated and the bolt under tension 
despite loads that try to both tension and relax the bolts hundreds 
or thousands of times a minute.

Your tower and rotator bolts are no different. Throwing the wrong 
kind of locking hardware at the problem will just make things worse.

The tower leg is generally soft compared to the bolt. The hard bolt 
can't stretch to maintain tension because it is working against a 
soft leg that bends, the soft leg can't spring back because it takes 
a set.

The same applies to clamping hard masts against soft rotor plates, 
or vice versa. The materials are poorly chosen, as are the bolts.

So we are left with the "glue it in place" or friction locking 
alternatives. That's why this is always such a headache, while 
things like connecting rods and lug nuts handle much more stress 
and vibration without any locks at all. There are so many 
combinations of bolts and materials what works for one person 
probably won't work well for the next fellow.

      
73, Tom W8JI
w8ji@contesting.com

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