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G8MNY  > TECH     14.09.19 08:02z 97 Lines 4366 Bytes #999 (0) @ WW
BID : 21491_GB7CIP
Read: GUEST
Subj: Casting Lead Throwing Weights
Path: HB9ON<IW2OHX<UA6ADV<CX2SA<GB7CIP
Sent: 190914/0758Z @:GB7CIP.#32.GBR.EURO #:21491 [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      .  .                     Your strength timing & skill
   T R E E     .      o.                   are more important. Make sure
     ||        v  ()/'. `.                the line is going to pay out
     ||         . ų .^    `.             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..
 _________                    _________
/         ~__........       /    hole.~-_........
\_________.Wire  cord       \_________.

And of course this is where it broke.

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

  Hammer                      Holding the lead remains in
  Rod                        pliers I heated them with a
     Mold                  blow lamp & let them drip
                           molten lead into the mold.
                        When cool, I removed the
  L                      steel plug, but found the
  E                      lead was well stuck the mold.
 A  Bench              I hammed it out with the vice
 D  Vice               support just the mold edge.
  

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   Blow
enough to push around, but not drip off.          L  Lamp
The thick paper towel was OK for this             E
unless you got it in the flame!                 A  Bench
Once in shape, smoothing off the surface        D  Vice
was just a quick pass of the hot frame           
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


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