[HBR] THanks for Offers of Parts and Opinions

[Mike Hanz]

I like the step drills as well.  I use them in the Bridgeport mill all 
the time - quicker than setting up a boring bar when all you're drilling 
is aluminum sheet metal.

If you have a small drill press, explore some ways to slow it down for 
larger holes (there are tables and formulas for this) and use Tim's hole 
saw approach with frequent pecks and washing with coolant -  WD-40 is 
superb in aluminum and will keep your tools from rusting in between 
building bouts.  Clamping the aluminum to the table is essential, of 
course.

The last item I consider essential is a couple of different sizes of 
what machinists call "center drills":

http://www.mcmaster.com/#combined-countersinks-and-drills/=bfkm53

I've used these for fifty years in all kinds of metals and drill 
platforms...the "flight deck" in my radio shack was built almost 
entirely with a 3/8" variable speed drill and a chop saw 
(http://aafradio.org/flightdeck/layout.htm )  The key to drilling and 
tapping hundreds of fastening points in the 1/8" aluminum channel was a 
couple of #1 center drills.  A #1 and a #3 high speed steel bit will do 
you nicely and you will be amazed at their ability to start on a tiny 
scribed mark and drill a neatly chamfered pilot hole without moving away 
from the scribed cross hairs, even with a hand drill.  In sheet metal, a 
larger set will eliminate having to switch to a normal drill bit after 
the pilot hole is drilled.  Best thing since sliced bread...

   - Mike  KC4TOS

On 3/14/2011 1:48 PM, Shoppa, Tim wrote:
> I would add my two cents:
>
> 1. I personally like nibblers to help with anything except a circular hole.
>
> 2. Step drills work very nicely on sheet metal. Specifically the "Unibit" brand ones are very fine tools. (I am less than impressed by the Harbor Freight knockoffs.) Drilling anything larger than about 1/4" in sheet metal with a "regular" spiral woodworking or metalworking drill bit is often unwise.
>
> 3. Hole saws can be productively on sheet metal but require some care.