[sdiy] Machining aluminum, part deux

[Jim Patchell]

Dave Magnuson wrote:

>
> I think this might prematurely wear your bits.  I realize that aluminum is
> fairly soft, but heat is the number one killer of drill bits.  I'd still
> use perhaps an 1/8" or 3/16" pilot hole before going to the full sized
> hole... it just has the bit doing a little less work, and stays cooler.
>

    The best way to deal with drill bit heat is to use cutting oil...and,
premium drill bits...although, the ones I use to drill panels are not
premimum...(Like I said in an earlier post, I prefer brad tipped drills, which
are really difficult to find in a premium grade).

    The cutting oil does make a bit of a mess, but it really does improve the
quality of the cut.  Plus, you don't have to wait for things to cool.  I use
the same cutting oil as I do when I use my lathe...where you need it...it
really impresses people when I cut steel with a carbide tip with all the smoke
that fills the room.

>
> Obviously, drill RPM and feeding speed are also factors in heat build up.
> Likewise, don't drill 40 holes in rapid succession... let your bits cool
> off ocassionally.
>
> Personally, I center punch, drill a 1/8" pilot hole, and then use a
> step-drill or "Uni-bit" to enlarge to full size.  Gentle pressure on the
> drill, and allowing it to cool every 5 or 6 holes.  I've had the same $30
> Uni-bit for 3 years and it still cuts like new (I also use it on 16ga steel
> and light gauge stainless).  An added benefit: after the hole is the
> correct size, you can use the next sized step to chamfer the edge of the
> hole...  Saves a lot of time.
>
> Dave Magnuson
>
> Resonant Frequency:
> resfreq at hoohahrecords.com
> http://www.hoohahrecords.com/resfreq/index.html