Mike,
In all honesty, I've no idea what they are properly used for by the end purchaser. The Engineering company I'm working to, is one I use to make me things occasionally and so when they got asked if they can turn wood, they came to me.
I am told that the recess is how it's held in some machine but mechanical or glue I don't know. The front face is dished (concave) by them, and the whole thing is used to polish something that needs to be extremely round and very smooth.
And as for why Burmese Teak, I've also only a hint. I was told they had tried other woods and materials but Teak worked and lasted best.
Les,
from the above, I'm open to any good guesses you have. I'm played out!
Les,
Actually the drawings I was supplied came in metric dimensions. But once I noticed that the various cylinder diameters were metric equivalents of imperial measurements, I looked again at the recess and sure enough, it was 9/16th x 1/4". This made things easy as I could buy a 9/16th Forstner bit.
Putting 2 bits of information together, I imagine, the machine that uses these cylinders is a very old, pre-metric engineering 'something-or-other', that does a specialised job, and as it's never gone wrong, it's never been replaced.
