G8MNY > TECH 14.09.19 08:02z 97 Lines 4366 Bytes #999 (0) @ WW
BID : 21491_GB7CIP
Subj: Casting Lead Throwing Weights
Sent: 190914/0758Z @:GB7CIP.#32.GBR.EURO #:21491 [Caterham Surrey GBR]
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
|| . Å³ .^ `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
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
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