John Smith writes:

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I have a piece of 4mm aluminium sheet which I
would like to use. Can anyone advise me on cutting circular holes in the
stuff. I have a 'Hole saw' set which describes its self as 'Bi-metal' It
works fine in wood and plastic. has anyone tried them on aluminium please?
Most of the holes will be for 2" instruments although there is a larger
Tacho which is approx 3.5 inches. any suggestions will be appreciated even
if they are of 'The don't even think about it' variety.

Hole saw will do a good job if you keep the following in mind:

1) Keep drill press RPM low, no more than 200 RPM.

2) Make sure work piece is properly clamped to the drill press table.

You can cut these holes dry, no lube req'd.

Lew