| |
G8MNY > TECH 12.12.18 11:34l 97 Lines 4366 Bytes #999 (0) @ WW
BID : 49051_GB7CIP
Read: GUEST
Subj: Casting Lead Throwing Weights
Path: IW8PGT<IR2UBX<SR1BSZ<LU4ECL<GB7CIP
Sent: 181212/1027Z @:GB7CIP.#32.GBR.EURO #:49051 [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
Read previous mail | Read next mail
| |
