> Sounds very ingenious and effective. The only problem is that I can't
> picture it. Can you give us a little more info?
>
> 73, Jim VE7FO
Let me try again. I have had good luck snapping toroidal forms in two to form
a home-made split suppressor at about 1/3 the cost of a commercial split bead.
Ferrite is more akin to ceramic than any other material I've handled. It is
extremely hard--almost impervious to scratching, grinding, filing, etc. So
scoring a toroid is difficult. I have managed to score them with a sharp file
(only to ruin the file I might add). Once scored, they snap along the line
every time.
Since they are so hard, scoring them is also expensive (files are not cheap and
the teeth are damaged almost immediately). So I ventured into the notion of
just snapping them and let the chips (pun intended) fall where they may. When
you strike the toroid, like with a hammer and chisel, they fracture into a
random number of pieces, making the unit virtually worthless unless you are
into jig saw puzzles with a tweezers and magnifying glass. What I have found
is that a steady pressure at a point load will snap them every time at the
point load.
Take an example of a 1.25" OD toroid. Using a machinist's vice (read smooth
jawed), I can place two metal blocks in the open vice, spaced about 1" apart.
Place the toroid in the vice (not yet clamped of course) with each end touching
the metal blocks. Using a 1/4" or so drill bit, I hold the shank of the drill
bit vertically on the opposite side of the toroid but in the middle of the two
blocks and begin to clamp the vice. When the vice gets clamped, the drill bit
puts a uniform point load on both sides (in the middle) of the toroid. Once
snug, the toroid will snap under the load right at the drill bit using a very
gentle turn of the vice handle. I have tried this several times using some
junk toroids laying around here and they snap in the same spot, making two
halves every time. On a couple of them, little chips would disappear from the
edges of the break, but the bulk of the mass is intact. The fracture is very
rough. But if you take care to keep the halves matched, they will go back
together again with only a minute hairline fracture crack separating the two
halves.
Once the toroid is snapped, my thinking is that they can be used to encase the
4 - #18 AWG wires going to the COP. Admittedly, it is only a single turn
through each core, but this eliminates the need to splicing the 4 wire harness,
which would likely the remaining warrantee on the Toyota 7 yr 100,000 mile
warrantee. They tell me the engine controller on this beast is $1200. That's
real money in my world...
Ford-N0FP
ford@cmgate.com
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