making spacers from one piece of steel

You could part off in the middle and trepan from both sides or part of to 4.5cm diameter and then trepan in to part off large washer then finish off small washer. You could also turn round in chuck and hold on small diameter to make second large washer.

Edited By David Clark 1 on 22/07/2015 13:11:37

cm and the other one whose name I can't remember, dm ?? that are 10 of those are used in the originally metric countries but ISO bless them have decided that only multiples of a 1000 can be used and that the rest don't exist.

Why use them - there is something vaguely obscene about saying something is about 75mm or 0.075m long. Equally it wouldn't be so daft to say something is about 800m away or 0.8km but 8 what ever they were called would give a better idea of accuracy. The mm units imply more accuracy than might be intended. For instance how accurate would some one expect about 6in to be be? If I measured something described like that - doesn't matter much - I wouldn't be concerned even if it was 5 to 7in.

Leaves me wondering what happens if people are only taught mm and m - guess they would only measure things rather than saying about 75mm long or discover cm and others and think in those terms. They could of course add a tolerance to their estimation in some number of mm.

Be thankful attempts to metricate time and the globe failed. In some ways base 12 makes a lot more sense than 10. Perhaps kids don't have to learn their 12 times table any more.

John

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Agreed, a decent hole saw that would withstand the journey through the material would probably cost more than the smaller piece of bar.

John

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G'day - Engines usually have the capacity (displacement) described in cc (cubic centimeters) - except the usual suspects that stick to cubic inches. - It depends on where you live.

Model aircraft use dm² for the wing area vs in², bigger ones use dm² vs ft² .

If the ISO mob have their way, will engines only be described in litres and milli litres?

Will the o/p ever return and tell us how he eventually made his spacers?

* Danny M *

O.K. mm in future. I am only learning. Thanks to everyone who participated,it did at least lead to a lively discussion. Following the general consensus,I shall be purchasing more steel. The main reason for the query was to try and learn a new technique if one was available.

Once again,Thankyou everyone.

Thanks for stimulating the debate! No stupid questions, only stupid answers...

Good question Roger, In my answer, a hole saw used on the lathe running in low back gear would be more practical than a trepanning tool, but my personal method would be as you have said, get a bit more steel for the small discs, save a lot of sweat.

I can get good quality second hand hole saws at my local second hand shop quite cheaply.

Ian S C