Tappet Bigend Hub 
Cam was singing a little rhyme he was making up to remind himself what things were made of.
I'm knocking on wood
That comes from the trees That grow in the forest

That comes from the rock That's found in the hills
I'm knocking on stone

I'm knocking on bricks
That are made from clay That is dug from the fields

That comes from err ???? Cam did not know what metal came from.
I'm knocking on metal

It comes from holes in the ground, Cam went to ask Uncle Bearing said Uncle Bearing about where metal came from
Holes
that
go
a
long
way
down 
If it comes from Not quite, said uncle Bearing, holes lets dig a big hole. it must be stone or its got to be clay
said Cam.

As Cam was carrying the rocks Uncle Bearing was digging out he Have you found any metal yet. began humming to himself a little song about metal.
Digging and digging What have we found Looking for metal Deep in the ground, Pink rocks, blue rocks, Yellow rocks, Green Metal's the only thing We have not seen. 
Cam looked at the stack of rocks he had. Not ordinary rocks, said Uncle Bearing That is what we call Ore. That is not metal that's a pile of rocks. But now we have to heat up the rocks Let us go and find a
fire 
That is called a furnace, said Uncle Bearing. That is a big fire, Said Cam. Inside there the rocks get much hotter than red hot, they get....

The metal is locked inside the rocks and the heat of the fire melts the metal inside the rock. When that happens the metal turns liquid and forms a pool at the bottom of the Furnace.
Stand back, said Uncle Bearing, I'm going to pull the plug out from the side of the furnace and let the liquid metal come out. 
The hot metal poured out of the furnace and ran into channels made in the sand in the floor at the side of the furnace.
That is hot, said Cam, it is a good job we were a long way away.

The next day Cam went to Uncle Bearing to Just one thing, said Cam, the furnace. When it is cold like it is now, he said, we have the raw metal which can be turned into you car, knives, forks even tin cans.

The words do not match I will A joiner works wood have to make up a new rhyme. A mason works stone
A builder likes bricks
But the foundry man
Works Iron.
