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Ball chain is a type of chain
made up with small hollow balls connected by small rods.
Each ball is made from rolling
a flat piece of metal over the interconnecting rods. The above picture
portrays two interconnecting balls on the left opened,showing how the
rods are secured.
Advantages of Ball Chain
- Smooth, chain that will not catch on clothing/skin
- Kinkless
- Easy to untangle
- Each ball acts as a swivel
Disadvantages of Ball Chain
- Not as strong as our 7x7 stainless steel wire or welded oval link
chain
- Will wear out sooner than our welded oval link chain when overly stressed.
Caution: Only soak the wick
in the fuel container as the hollow balls will soak up the fuel and can
cause the chain to catch on fire whilst spinning.
Can I use ball
chain on my fire poi set? |
This depends on the type and
size of your ball chain, the weight of your fire head, and your swinging
style.
Types of Ball Chain:
 Aluminum ball chain.
Not suitable as it has a high thermal conductivity and breaks very easily.
Be aware that coloured and decorative ball chains are quite often aluminum
underneath.
Mild Steel ball chain.
Good with correct sizing, shorter life compared to Stainless Steel.
Quite strong. Normally coated with Nickel for greater abrasion and corrosion
resistance, however as coating does not effectively get inside the ball
and the ends or insides of connecting rods, rust and abrasion wear will
occur within the chain. Overheating will also cause nickel plating to
come off mild steel.
 Stainless
Steel ball chain. Very good with correct sizing. Excellent longer life
abrasion and corrosion resisting properties. Stainless steel has a much
lower (1/3) thermal conductivity than regular steel and will heat up
slower under a flame. Benefits of stainless steel include: Corrosion
resistance, Fire and heat resistance (retains strength), attractive
appearance, strength to weight advantage, high impact resistance, and
longer life.
Sizes of ball chain
as supplied in our shop
Size #13 (Ball diameter 1/4inch
or 6.3mm has an average tensile strength of 90lbs or 41Kg
Size #15 (Ball diameter 5/16inch
or 8mm has an average tensile strength of 120lbs or 54Kg
Poi spinning styles
If you spin an 80cm POI set
with 140gm Cathedral fire heads at 2rev/sec the force on the chain will
be approximately 14 times greater at the bottom of the swing. Which
is like having an unmoving 2Kg POI head pulling down on the chain.
If you spin the same set faster
at 3rev/sec the force on the chain will be approximately 30 times greater
at the bottom of the swing. Which is like having an unmoving 4.2Kg POI
head pulling down on the chain.
If you wrap the POI around
a limb you could effectively halve the spinning radius and hence double
the force again.
Kicks and quick changes of
directions will also put greater stress on the chain even over 100 times
the resting weight of the POI head
Always allow extra margins
for any additional stresses (forces and heat) you may put onto the chains.
If you like big fire heads,
faster spinning with kicks and wraps you are better to look at welded
oval link chains for you POI cords.
*"the force on your hand
is equal to the mass times the velocity squared all divided by the radius."
How do I attach
ends to my ball chain? |
In order to attach quick links
and fire heads or handles to ball chain it is recommended that you use
a type "A" coupling.
The coupling has an eye for
attaching quick links and attached bowl which cradles the ball chain.
Drop the ball chain into the
cradle by passing the connecting rod through the slot in the side wall.
Once the ball chain is in place crimp the slot together to prevent the
ball chain coming out again.
Never attach wick heads or handles
directly to the "A" coupling as this will cause undue side pressure
on the first connecting rod resulting in shorter life of the product.
Use quick links shown below
or other suitable connector.
 Dangerous
use of Mild steel key/split rings : Continuous heating
and reheating of these rings with any centrifugal forces causes the ring
to open up. Standard cheap low carbon key rings will weaken at 260 Deg
C. within 2 minutes!
Even small stainless steel splitrings
will open. Remove risk, increase product safety and product life by using
stainless steel quicklinks. See Stainless
steel quicklinks and parts
Use a quick link at the fire
end and tighten the quick link with pliers to prevent it coming undone
once the head is attached.
How do I check
my ball chain for wear and tear? |
Referring to the diagram above.
If you have nickel plated steel
ball chain look for signs of rust and wear marks at point A and signs
of the ball opening too much at point B.
If you are using Stainless steel
ball chain look for signs of the hole at point A getting larger and again
the ball opening at point B.
Depending on your style of spinning
you could see signs of wear at any point along the chain length.
No
matter what you decide to use, always check your equipment before using
it.
Caution: Only soak the wick
in the fuel container as the hollow balls will soak up the fuel and can
cause the chain to catch on fire whilst spinning.
See also Other
metal parts used in making fire poi, Stainless
steel equipment and parts, Fire
poi
References: HSE
UK, Nickel institute, Fire
Science and Technology, The
stainless steel information center, American
Iron and Steel institute, Fire
research information Services
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