K Ludger wrote:

"K Ludger" wrote in message
...
I've got a job coming up to drill around 300 x 25mm diameter holes in some
powder coated steel electrical enclosures. The metal is 1mm thick,
probably 30 - 35 thou. Punching is out, I need to do this using my drill
press.

I've done a bunch of holes in the past using a step drill, and then spent
almost as much time again deburring the holes. I'de very much like to
avoid using coolant or Trefolex due to the cleanup involved with the
enclosures.

I'd like to drill the holes in one go (ie not pilot then change & drill)
any recommendations as to the best approach or tool that I should use?

thanks


Wow so many replies - thanks to all!

I'm leaning toward drilling a single hole then using a Green Lee or Bramley
punch (wrench driven unfortunately).

My drill press while substantial has been retrofitted with a 1/2 hp single
phase 240V motor and with the current chuck (not morse taper) would not
handle a rotabroach. The enclosures are an off the shelf prefabbed item my
customer uses regularly. They are around 1'x1'x1' and are difficult to
clamp/locate on the drill press. The hole location is not critical within
0.1" will be ok, its for a cable gland to be fitted into.

On the topic of chassis punches, will a 1/2 drive air wrench similar to the
one at the link below drive a Green Lee or Bramley 1" punch?

http://www.toolstation.com/images/li...bbig/45203.jpg

Would using soap / beeswax aid the punching operation?

Many thanks for all of the advice.

Seasons greetings to all.

I may be a bit late to the party...

This 1' cube is more or less like an electrical pull box? One side
removable cover and a flange on that side the cover screws onto? If so,
consider the following:

1. Make an 18" square baseplate out of 3/4" plywood.

2. Screw down 1x3 hardwood cleats onto the plywood to form a 1' square
opening that the enclosures will snugly seat in.

3. Attach one toggle clamp to the cleat on the open side of the
enclosure and adjust it to solidly hold down the enclosure when clamped.

4. Attach this simple fixture to your drill press, positioned
appropriately so that the hole location lines up with the spindle.

5. Drill the holes with a suitable step bit, hitting it with one of the
dry lub sticks occasionally.

Refine this overall process as needed, upgrading the fixture to a three
sided corner is needed if the enclosures tend to twist. I expect this
method will let you do an enclosure every 60 seconds or so with minimal
fuss, expense and cleanup.