Today we continued on with our work on the workbooks containing the information about hand tools. The pages i workedon today were primarily concerning the types of saws, how to sharpen the blades and also terminology used to describe a saws attributes. The kerf is the width of the cut wich is generaly 1.5 times the actually width of the saw blade, because the teeth splay outwards. By having this wider cut made by the teeth, the saw is able to sink deeper and deeper into the wood without getting any friction and thus making the saw harder to operate.
I also learnt a bit about oil stones, that the main synthetic stone used is made of aluminium oxide and that natural stones give a much finer, more precise finish to blades of chisels and the like but cost alot more, so only a fine furniture maker would purchase a natural stone. Oil stones need to be washed in oil to float away the pieces of metal and stop the stone being clogged up. If an oil stone becomes clogged up due to the drying out of the oil, it is nescessary to wash the oil stone with petrol or kerosene.
After lunch we moved back into the classroom for a presentation made by a man that works for Bell Fire, called Jim. The basic outline of the course was to inform us on why we need fire extinguishers, how to use them and what different types of fire extinguishes there are. I found Jim to be very engaging and spoke with a clear a loud voice and often used vibrant hand gestures and vocal effects to describe explosions and other situations. I found Jim informative and entertaining.
During this presentation i learnt that under law it is nescessary to have a fire extinguisher in your car, you must be trained how to use it if you employ other people and if you're an employee you must do everything you can to extinguish a fire otherwise your ass is liable and you can be sued. It is nescessary by law for any place of employment to contain at least one portable fire extinguisher and a wall mounted fire hose reel. The fire hose reel should not be used to carry out other duties in the workplace.
All fire extinguishers have been standardised in Australia to be painted red. There are four tyes of different fire extinguishers, each singalled by a different coloured band around the top part of the cylinder.
Black Band - These are carbon dioxide fire extinguishes. As explained and demonstrated by Jim these are rather useless in extinguishing any fire outdoors and if inside there is air conditioning they useless as well. The only plus side is that they create absolutely no mess.
White Band - These are dry powder (monoammonium phosphate) fire extinguishers. These are rated for all three main types of fires, paper, flammable liquids and electrical. The powder is non toxic. These were proved to be extremely effective, as they are very efficient at puttingout flammable liquid fires and also because the powder, in the air, protects the user from heat as it stops the heat radiation.
Blue Band - These extinguishers are filled with a foam. Jim did not discuss these in great detail but he stated that they are't that effective and are not rated for electrical fires, and when used in bad weather conditions the foam can quickly be washed away.
No Band - This signifies a fire extinguisher that contains only water, so it is not rated for electrical fires or flammable liquid fires.
Classifications of fires.
A) ordinary combustibles - tree products
B) flammable liquids - plastics
C) gas
D) flammable metals
E) electrical fires
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