Date: Tue, 28 Aug 2018 15:29:03 -0400
From: Warren Munro <wmunro1@hawaii.rr.com>
To: towertalk@contesting.com
Subject: [TowerTalk] drilling chrome-moly mast
<All
<This may have been mentioned before, but my machinist brother-in-law advises
drilling starting with a quite small bit and then use new gradually larger bits
as you step up in hole size. This will cut down on the annealing, and will help
eliminate the "bite" at the <end of the final hole.
<73
<Warren KH6WM
## IMO, trying to drill a .375 hole into a 2.00 OD X .375 inch thick
heat treated 4130 chromolly mast..... while up at the top of a tower would be
a night mare. And trying to free hand it with a hand drill ?? Good luck
with that.
The original idea was to... pin the mast, so it wont slip. IMO, it would be
much easier and simpler to just use the correct rotor clamp in the 1st place,
like the K7LXC or K7NV units. They dont slip period...end of problem..at
least at the rotor
end of the mast. Where the boom meets the mast... that assy is easily done
with 2-3-4 of the DXE super mast clamps. They come in 2 inch ID, 2.5
inch ID..and also 3.0 inch ID. I used the F12 concept, which uses 2 al
plates, one is mounted to mast
using several of the DXE mast clamps. The horizontal al plate is mounted to
the boom with either DXE SS U bolts + solid al saddles, OR a pair of DXE
mast clamps. Each al plate is .375 inch thick. Plates are mated with 4 x
.375 inch bolts.
The 5th bolt is typ .5 inch. I drill and tap the 5th hole into the vert
plate. Vert plate is mounted to mast before hand. Horz plate is mounted to
boom. Boom brought up and mated to vert plate simply by sliding hole #5
over mating stud #5..
done deal. Then align the boom, such that the 4 x remaining holes line up.
Stuff 4 x remaining bolts in..and u are done. F12 called that assy the
..easy on mount. I just took the same concept, and beefed it up a bunch.
And no, the vert plate
will not spin on the mast, it cant. Those DXE super mast clamps are things
of wonder..with a massive a mount of clamping force on each clamp. 80m
rotary dipole gets a 8 x 14 vert al plate..and a 8 x 17 horz plate. 2 x DXE
super mast clamps used on vert plate...and 6 x dxe ss u bolts with solid
saddles used on Horz plate. The 40m assy gets a 8 x 17 vert plate..and a 8 x
14 horz plate. 40m vert plate gets 4 x DXE super mast clamp..and horz
plate gets 2 x DXE super mast clamps. Nothing can slip
on the mast, no need to pin the mast. K7NV small PP with its 2 inch mast
clamping assy. All TQ balanced, so minimal tq required to rotate..and hold it
in a wind.
Jim VE7RF
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