bi-metallic strip mobile
This is a mobile worked by a bi-metallic strip & a candle designed in collaboration with Jacky Champ.
The tissue paper wing flaps to & fro causing the mobile to spin slowly round
The long piece of wire the machine hangs from ensures that the candle always stays level
This is a close-up of the mechanism, it is made up of three bits of bent wire.
The first and longest forms the suspension hook, holds the candle by winding round it then going underneath, supports the bearing (plastic tube) and finally forms the end-stops for the flip-flop.
The flip-flop is bent from a much shorter piece of wire which goes through the bearing tube then is bent up & over the candle, through the bi-metallic spring then is firmly attached to the other end of the bi-metallic spring by folding, crimping & binding with some very thin brass wire.
Finally the wing is taped to a short length of wire attached to the other end of the bi-metallic strip. As it is heated by the candle flame the stip uncurls, causing the wing to go vertical then start to go down the other side; this causes the flip-flop to over-centre which moves the strip out of the flame. The strip then starts to cool & curl up again, this causes the wing to move back and tip the flip-flop back again so that the strip is now in the flame and so on.
This is a close-up of the bi-metallic strip showing its attachment to the flip-flop at one end and the wing support at the other.
The bi-metallic strips can be bought from OPITEC for 60 pence each.
Link to movie
Link to another movie
pie-dish spinners
These can be made from aluminium pie dishes
They are balanced on pins sellotaped to a piece of bent wire
You can make dimples in the aluminium by pressing with the tip of a ballpoint pen, support the back of the aluminium with blue-tack.Make the dimple first of all, then you can have several goes at it.
Only the lowermost spinner need be made of aluminium. Cut out dimples and glue them to cardboard spinners to form bearings. You have to trim bits off the spinners to get them to balance properly.
This is a better way of making a bearing using a paperclip & short length of drinking straw
This is a detail seen from below, the bearing runs on a pin sellotaped to a bit of bent wire
Detail from above
Link to movie
Link to another movie
Link to another movie
Link to another movie
candle seesaw
This is a candle seesaw
When both ends are lit it will drip wax alternately from one end or the other causing it to rock to & fro. The pivot is made from a card cutout
one side of the pivot has a short length of narrow drinking straw slid over it, this gives it a slight rolling motion which prevents the seesaw action from becoming too extreme. It is essential that the centre-line of the candle should correspond as closely as possible to the pivot line. The extra fold at the top prevents the card from bending as the candle is slid into the square hole. The candle should be balanced as nearly as possible before the ends are lit, although it will automatically compensate for any minor imbalance. It is deceptively dangerous; as the candle gets shorter the rate of rocking gets quicker, if left unattended it will eventually burn through the pivot and drop into the pool of hot wax that has formed underneath.
candle roundabout
This is a candle roundabout
The hot air from the two candles causes the structure to rotate slowy. This is the bent wire structure without the aluminium pie-dish 'sails' or the candles
This shows one of the ends which comprises a triangular support to hold the candle and a 'paperclip' to hold the sail
The structure pivots on a bend in the wire which rests in the dished base of an inverted coke can
This shows one of the sails held in a paperclip
And this shows the candle on a triangular support, the hot air from the candle travels up the concave face of the sail
scrap-paper mobile
This is a mobile made from a single A4 sheet of scrap paper
the paper is cut lengthways into about six triangles, each one a bit smaller than the last. They are strung together using a needle & thread, starting with the smallest and working upwards
as each additional triangle is added its balance point is found by pushing the pin through the upper edge to act as a pivot
although the paper can be stiffened by rolling it around a pencil as in this instance any origami shape which stiffens a long thin paper shape will do.
This is one made from drinking straws, short bits of straw split lengthways have been used as sliders, so that each level is easily adjustable.
Similar thing but doesn't really work because it takes too much force to pivot something round a horizontal axis
read about whippletrees
back to main site
my email is davidvwilliamson@hotmail.com