Subject: Re: Machining Aluminum?

From: Michael Latcha <[email-masked]>
Date: Thu, 12 Sep 1996 14:53:07 -0400

I would suggest that you cut the 1/2" aluminum plate on a bandsaw (speeds
for wood are generally okay for aluminum) instead of a table saw.  Cut the
throat by drilling small, closely spaced holes around the INSIDE of the 3"
diameter throat, then break or saw through the spaces between the holes,
clean up with files (finishing rasps of files work well for fast stock
removal of aluminum).  The ledge for the Lexan insert can be made on your
router table with a rabbitting bit (ball bearing type) and light cuts. 

People have gotten away with using end mills in drill presses and seem to
be very proud of the fact that they have survived, but the fact of the
matter is that drill press spindles are not made for the side loads seen
in milling.  In addition, if your drill chuck pops out of the taper in the
middle of the cut, it can be a very eye-opening experience... 
 
--------------------------------------------------------------------
Michael A. Latcha, PhD                     VOICE: (810) 370-2203
Associate Professor                        FAX:   (810) 370-4261
Department of Mechanical Engineering       Email: [email-masked]
Oakland University
Rochester MI 48309-4401

On Thu, 12 Sep 1996, Adam Whiteson wrote:

> I am a woodworker who occasionally needs to work pieces of aluminum.
> Right now I need to make an inset plate for a router table out of
> 1/2" aluminum. The plate will be 10"x12" with a 3"dia circular
> throat cut out of the center.  The throat needs a ledge to
> support a 3" Lexan insert.
> 
> My plan is to cut the rectangle with a table saw and then 
> machine the throat on a drill press using a 3/8" mill end.
> KBC has mill ends for aluminum.
> 
> Will this plan work?  I'd appreciate any comments.
> 
> 
>             Thanks - Adam
> 
>

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From: [email-masked] (MARK CENTER)
Date: Fri, 13 Sep 1996 20:50:41

>KBC has mill ends for aluminum.

you may be able to cut the aluminum with a table saw with a carbide tipped 
saw. Find a way to slow the saw RPM if you can.

Drill a hole in the center of the aluminum.
Mount the aluminum on your drillpress on a die spring stripper bolt or axle 
shoulder bolt on top of a piece of wood.
Shim with washers so the aluminum barely spins
Swivel your table or head to increase or decrease the radius of the hole.
Use a four flute 1/8" end mill. Smaller=less holding force
do not use end mills made for aluminum, their cut is to aggressive
drill starting holes on inset and thru radius.
mill inset raduis first.
finish cutting
2000- 3000 RPM

this is bull pucky. a mental excersize. it may even work.

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From: [email-masked] (Jonathan M. Elson)
Date: 13 Sep 1996 18:15:02 GMT

Adam Whiteson ([email-masked]) wrote:
: I am a woodworker who occasionally needs to work pieces of aluminum.
: Right now I need to make an inset plate for a router table out of
: 1/2" aluminum. The plate will be 10"x12" with a 3"dia circular
: throat cut out of the center.  The throat needs a ledge to
: support a 3" Lexan insert.

: My plan is to cut the rectangle with a table saw and then 
: machine the throat on a drill press using a 3/8" mill end.
: KBC has mill ends for aluminum.

How will you hold the workpiece?  Don't even think you can hold it with
your hand!  The side forces when milling are hundreds of times greater
than when drilling!  It will be ripped out of your hands and thrown
across the room.  I have had this happen with work held in a vise, but
not tightly enough.  If you want to do this on a drill press, you must
have the chuck attached with a screw to the spindle.  Many drill chucks
are open at the back end so that reversing drills can have the chuck
held by a (usually left-hand) screw.  You need a screw (probably right
hand) to hold the chuck on the taper.  A small screw (6-32 or 8-32) is
sufficient.  Then you need an X-Y table to clamp the work to, and move it 
around, to complete the 3" hole.  Another way to do this without the
X-Y table is to mount the plate rigidly, and use a fly-cutter.  You
probably still need the anchoring screw for the chuck.  You also need
to have a VERY slow speed for this operation, something under 200 RPM.
The fly-cutter is sometimes called a circle cutter.  You can find one
in the best hardware stores.