A drilling machine for thin metal foils and flashing.

by Ralph Klimek  Oct 2009

It is often necessary to drill a larger hole in a small piece of flashing. Lately I have had to do a lot of these for assorted projects and as you well know, drilling a large hole in very thin metal does not work, and if it does the hole is very ugly with torn edges.  This simple machine will even permit permit holes to be drilled into light gauge copper flashing which as you know, copper sheet  is extremely difficult to drill or ream  cleanly without tearing.  

This machine is made from heavy brass angle stock. It is longer than absolutely required to permit simple mounting in a bench vise and give  good clearance to the drill bit as it will bite and plummet into the air, not the vise.

I have tried make this tool with aluminium  , and allthough it works, aluminium  is really too soft. Brass better resists the sideways forces of the drill bit and does not wear.

I have allowed for the most popular hole sizes, including a massive 5/8ths drill because many of my RF projects require this large hole for PL259 and type N connectors.

Construction and usage should be self evident, allthough I will say it anyway!  To use this machine, the work piece is clamped between the brass sections.

The brass sections are held true by a couple of 6MM screws, tapped into the bottom piece. This has proven to be sufficiently robust.

Contruction sequence:

first bind the two brass sections, then, drill two  5MM holes for the attachment screws and tap for 6MM. Attach and screw down the two elements. Only then drill  the pilot holes then drill the  desired sized  work guiding holes.  This will ensure that the work holes are absolutely true.  A drill press is essential. Cheap n nasty Chinese made ones are now available for pocket money prices and will last long enough to give good service to the home workshop.

The tool can be used with a drill press or hand held drill.

Try doing this freehand in light copper flashing  with just a drill or reamer !


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page created  Tue Nov  3 18:12:56 EST 2009