# Cutting Holes in Sheet Metal



## Kittyhawk (Jan 5, 2012)

I need to cut a 57mm hole in some 2mm Aluminium sheet. I was going to use a fly cutter in the mill, but was wondering how best to hold the sheet on the table?


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## Ken I (Jan 5, 2012)

Kittyhawk - you can do that - its called treppanning - using a narrow cutting tool in the boring head - normally 2 or 3mm wide - with a slight angle on it so it cuts off the larger diameter first (at which point the disk you have cut out starts to spin - stop).

Of course if its the disk you are after producing then you want the angle the other way.

Just clamp it down onto something sacrificial - like MDF board.

If its the disk you are after or are concerned about what it will do on breakthrough - stick the plate to your sacrifical (MDF) with double sided tape. (superglue - whatever.)

You also get cheapo trepanning tools that revolve around a predrilled pilot hole - I have one and it works surprisingly well - but accuracy will not be as good as with a boring head.

With a boring head - set it to a scribed line - aiming to be slightly undersize - take a small cut - measure and adjust.

Ken


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