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G8MNY  > TECH     12.06.22 11:00l 98 Lines 4368 Bytes #999 (0) @ WW
BID : 23689_GB7CIP
Read: GUEST
Subj: Casting Lead Throwing Weights
Path: IW8PGT<LU4ECL<VK2RZ<VE3CGR<WG0A<N3HYM<PE1RRR<DK0WUE<GB7CIP
Sent: 220612/0801Z @:GB7CIP.#32.GBR.EURO #:23689 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To  : TECH@WW

By G8MNY                                (new Jul 09)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)

The other day setting up an HF aerials for a club demo station, I broke one of
my lead throwing weights after it hit concrete ground too hard.....

TWIRLING (Slingless shot)
This method uses stronger line & heavier weight. A weight > 100gm, e.g. a 200gm
plumb bob is tied to nylon cord (make sure the fixing is very good & will not
pull out!) & you twirl this around in a vertical manner in line with the target
with a metre or so of line. Your hand needs protection & a leather glove must
be worn. As there is danger of 'miss fire' is you let go at the wrong time,
make sure other people & cars etc. are well clear!

 M E D I U M   twirl dia
  S I Z E D      . Ú .                     Your strength timing & skill
   T R E E     .      o.                   are more important. Make sure
     ||        v  ()/'. `ú.                the line is going to pay out
     ||         . ų .^    `ú.             freely & that you are not
     ||          /  \    Line laid out     going to get entangled.

I have put lines into trees at 18M with this method. Due to the heavy weight,
tree grabbing of the line is not a problem, except for miss fires where the
shot has to be pulled out from the wrong branch etc. In that case beware of
knotting the cord around a branch!

Often a high shot is best coming down in the tree if you can't reach the other
side of the tree!

=============================================================================

The original weight was 1.5cm square cross section 4cm long with point ends &
had an embedded copper looped end, This soon came out, so I drilled a hole..
 _________                    _________
/         ~Ä__........       /    hole.~-_........
\_________.ÄWire  cord       \_________.Ä

And of course this is where it broke.

So I had to recast the lead                      ³    ³
weight, but what could I use                     ³ally³
a mold? I found a piece of                       ³    ³
spare ally aerial boom was                       ³mold³
just the right size, but it                      ³    ³
need one end temporally                          ³    ³
blocked up. This I did with                      ³____³
some a steel plate, folded &                     ³Ý  Þ³
ground to make a good tight fit.               ±±³   Þ³±±  Bench
                                              ±± steel  ±± Vice
                                              ±±  plug  ±±

  Hammer                      Holding the lead remains in
  RodÛ                        pliers I heated them with a
  ³  Û ³Mold                  blow lamp & let them drip
  ³  Û ³                      molten lead into the mold.
  ³²²²²³                      When cool, I removed the
  ³²L²²³                      steel plug, but found the
  ³²E²²³                      lead was well stuck the mold.
 ±±²A²²±±  Bench              I hammed it out with the vice
±± ²D²² ±± Vice               support just the mold edge.
±± ²²²² ±±

However the 1st attempt was poor with the cold lead not bonding well & little
bit came out, not 1 strong solid piece!

For the 2nd attempt I warmed the mold up as I melted the scrap bits & also
added solder flux, this encouraged the molten lead casting to adhere to itself
better.

I repeated the previous removal scheme but used a much bigger punch rod so as
not to flatten (wedge) the lead in the mold. I found centre of the piece looked
good, but the ends were poor. As I wanted rounded end (to slip through trees
easily) I went about hot reshaping the ends.

The trick I soon found was to judge the     Paper /~~\
temperature were the lead was just soft     Towel ²²²²  Blow
enough to push around, but not drip off.          ²L²²  Lamp
The thick paper towel was OK for this             ²E²²
unless you got it in the flame!                 ±±²A²²±±  Bench
Once in shape, smoothing off the surface       ±± ²D²² ±± Vice
was just a quick pass of the hot frame         ±± ²²²² ±±
to just wet the surface.

I was pleased with the result, not a masterpiece, but good & strong enough to
take another drilled hole & possibly a few more drops onto concrete!


See my TECH bul on "Tree Antenna Sky Hooks"


Why Don't U send an interesting bul?

73 De John, G8MNY @ GB7CIP
b


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