Square Roundabout


This is a development of the Cambridge merry-go-round and, in days gone, it would probably be based around a cart wheel and axle. Sadly, these days, such things are in short supply so we have tried to concoct a modern equivalent. Our Group is based in an urban area in Greater London and abandoned car wheels with bald tyres waiting to be recycled are commonplace.


Equipment


- 8 x 4m (12ft) spars
- 4 x 3m (10ft) spars
- 4 x 2.1m (7ft) spars
- 6 x 1.0m (3ft) spars

strong metal pipe, bar or heavy spar 1.8m (6ft) long

1 disused car wheel (with tyre removed) or similar

1 circular piece of 20mm thick plywood cut so that it overhangs the wheel by approx 50mm (2") all round and has a hole cut in the centre so that it just passes over the metal pipe (a)

1 circular piece of plywood similar to above but 200mm (8") bigger in diameter and with 8 holes drilled, in pairs, 150mm (6") either side of the cross centre lined 50mm (2") in from the outer edge. (b)

1 tin grease

2 metal plates 300mm (1ft) square with a hole in the centre similar to the plywood ( c)

40 lashing lengths

4 short ropes

Heavy metal skewers and mallet.

Method

Sink the metal pipe vertically into the ground by 600mm (2ft) ensuring that it is firm and truly upright.

Place the wheel over the metal pipe and anchor it down using the heavy skewers.

Place the smaller piece of plywood on top of the wheel followed by 1 metal plate.

Coat the top of this metal plate with grease and place the other metal plate on top of it.

The second, larger piece of plywood fits on top of the metal plates (d).

Place 2 x 4m (12ft) spars on top of the plywood, one either side of the metal pipe and raise them up using two block of wood or bricks.

Place two more 4m (12ft) spars on top of the first two, at right angles to them. Lash the spars together where they cross.

Remove the bricks and lower the spars so that they rest on the plywood and are aligned with the holes. Pass the short lengths of rope through the holes and attach the spars to the plywood.

Lash 1 x 1m (3ft) spar between the ends of each pair of 4m (12ft) spars so that they stand vertically. A tripod lashing is probably best although you could use a square lashing to fix the vertical to one horizontal, then bind the two 4m spars together. This will give you a frame consisting of 4 long spars forming a cross with a short spar standing at each end and a metal pipe up through the centre. (e)

Take 2 x 4m spars, hold them either side of the metal pipe and lash them to the top of the vertical spars.

Repeat with the last 2 x 4m spars so that you have one cross above the other.

Lash the upper spars where they cross.

Lash 2 x 3m (10ft) spars between the ends of the lower cross spars so they form two triangles opposite each other and act as a brace.

Repeat for the upper level.

Lash the last 2 x 1m spars vertically on opposite sides of, but close to the hub to support the centre of the top 'cross'.

Finally, use the 4 x 2.1m spars to brace the frame between the lower level near the centre and the outer edge of the top 'cross'

Note:

It is possible to use more 4m spars to produce a more circular round a bout but that would drastically increase the overall weight