Grant KZ1W wrote:
>Another place I use Nordlocks is for rotator base bolts. Since
aluminum
>has about 2x the expansion per degree F as steel (alloys and temper
make
>big differences), there is temperature cycling of the bolt load. It is
>also the case that I don't want to mess with Loctited bolts when on the
>tower, but with the cautions, it works. Used rotators I've bought
always
>seem to have roughed up base threads, and a Helicoil insert is the
>ultimate fix, since they are stronger than the raw aluminum threads.
>
If the threads in aluminium rotator castings aren't too badly damaged, a
simple alternative is to use RED Loctite to fix short threaded studs
permanently into the rotator base. (Even better, insert set-screws from
inside the base casting to leave protruding studs, and again use Red
Loctite.) During installation, the studs pass through the holes in the
tower plate, locating the rotator safely in its correct position even
before you add the nuts and washers.
>Nylocks everywhere else.
Make that NEW Nylocs, every time.
Threaded studding can also be used to rescue damaged threads in the bell
casting on Ham-IV and similar rotators. Again, clean out the threads and
insert stainless steel studs, fixed permanently in place using Red
Loctite. Then use Nyloc nuts to secure the two castings together.
(Because the original self-tapping screws cause corrosion damage in the
aluminium casting, you may need to re-tap the holes to a slightly larger
size. Although you may lose some thread engagement, the Red Loctite will
help fill the gaps.)
73 from Ian GM3SEK
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|