On Sun, 21 Dec 2008 13:14:20 +0900, "K Ludger"
wrote:

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

===========
If drill you must, you might look at a hole saw.

I don't see a 25 m/m listed, but this will give you an idea.
http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32
you will also need the driver
http://www.use-enco.com/CGI/INPDFF?PMPAGE=606&PMCTLG=00

As the metal is pretty thin you might want to consider an
adjustable hole cutter. These are dangerous.
http://www.use-enco.com/CGI/INSRIT?P...&PARTPG=INLMK3

An other option if your drill chuck is big enough [3/4 inch] is
to use a rotobroch. Good but spendy
http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32

http://www.rotabroach.co.uk/en/produ...s/default.aspx
shows an exact 25m/m their sku SRC250. They also show a morse
taper adapter to replace the chuck.

Most any good mill supply house should be able to order for you
if they don't have in stock. Enco items are exmples.

Let us know what you decide on and how it works


Unka' George [George McDuffee]
-------------------------------------------
He that will not apply new remedies,
must expect new evils:
for Time is the greatest innovator: and
if Time, of course, alter things to the worse,
and wisdom and counsel shall not alter them to the better,
what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman.
Essays, "Of Innovations" (1597-1625).