Thread: Governor repairs

Originally Posted by JDNSW

Interesting the changes in skills and ways of doing things.

In the 1940s when the original was designed, the pulley was made of cast iron, because this enabled it to be cheaply made close to the shape required so that minimal machining was required - machining was expensive, because there was no such thing as a NC lathe, and the the best that would be available might be a turret lathe, although that may not have saved a lot of labour on this item. But also, material was expensive, so that using machining to just remove large volumes of metal was not normal practice. The keyway would probably have originaly been cut in a shape, or possibly using a purpose made broach.

But in that time, most tradesmen would have had little hesitation in making the pulley from either steel or aluminium using a simple workshop lathe and cutting the keyway by hand, mostly with a file.

John

John,

Setting up for mass production also makes a casting worthwhile whereas a 1off is relatively simple nowadays on an NC/CNC machine.

Our machinist found it a challenge because we manufacture pneumatic cylinders so all we do is machine threads on rods, machine spanner flats, cut aluminium extrusion to length and assemble. The fact that he is 'interested' and runs an old Rover also helps.....

Regarding the keyway, I've just been offered a filing machine which could have been used to make the keyway. When discussing it I found that a lot of people ('engineers') hadn't even heard of a filing machine. A quick look on the interweb and I don't think they are made any more.
I'm lucky to have a customer who puts keyways into sprockets, pulleys etc for a living so it'll just cost a couple of beers.



Colin