The following comments are from postings to the mailing list in July, 2003, and personal emails:
Lynn E. Hanover:
A fine toothed crosscut carbide blade mounted backwards. Just over half the metal thickness of blade height showing. Put some masking tape on the sheet to keep from scratching. Go slow. Cut half way through on each side. For heavy stuff, like plates or bar stock, turn the blade to the normal direction.
My chop saw does just fine if I go real slow. The sides of the cut look polished.
I used an 80 tooth plywood carbide tipped blade and lots of wax.That stick in a cardboard tub is best.It's bees wax and paraffin mixed.The best for all the .063 is a cheep old cast iron band say.I bought an old 10 inch Delta for $75.00,put deferent pulleys on it to slow it down.It cuts better and is WAY quieter.
For the sheet, I got an old set of Skill power sheers.A drill motor with
a quick cutting kind-a-nibbler on the end.Sheet metal shops use them all the
time.There $145.00 new but look around,I got one out of the little nickel
for $35.00.It needed a new jaw but there easy to fix.It takes a little practice
but man are they fast.With just some filling on the edge for that perfect
straight edge and your skinned.
Bruce A. Frank:
In the welding shop in which I used to work we used a sixty tooth carbide circular blade from Home Depot on our table saw. It was lubricated with a waxy lubricant that came in a cardboard tube like a grease gun cartridge. We got the lubricant from the Skill service center but any hard ware or lumber yard store should carry the lubricant. It is a bees wax and paraffin base and commonly used when cutting wood. Straight paraffin will work also and is available from most grocery stores.
Before you make the cut in the aluminum you carefully run the lubricant into the teeth of the running blade. Refresh every 30 to 40 inches of cut or rub it on the surface of the material being cut. Or both.
With such relatively thin aluminum [Ed: Bruce is referring to 0.063" sheet], if you are cutting straight lines using the fence you will find that placing a piece of particle board or plywood under the aluminum will improve the cutting process. Thin material on a table saw is not supported right at the blade and tends to chatter which is hard on the blade and sort of requires you to match the feed speed to the chatter frequency to get a good cut.
[...] try rubbing the lube along the line of the cut. We found, though some disagree, that the carbide blades worked better in aluminum than the regular steel blades. The smoothness of the carbide didn't seem to give the aluminum a place to stick.
I should add, use a face shield and button your shirt collar up to the top to keep hot chips out of your shirt. Wear gauntlet type gloves to protect your hands and wrists from hot chips. A hat to keep hot chips off your scalp is also a good idea....if you haven't learned all this already.
[...] you want some "Magi-Tap" for aluminum or similar NON-Chlorinated tapping oil. Tapmatic (for AL) is also a good one. Squirt a bit on the metal and saw away. Lets the chips tear away cleanly form the saw blade (and the drill bit).
Cutting sheet metal with the table saw works nicely but is not without some danger, as I found out today. I cut a C channel apart and used the saw's fence to align the piece. Just before the end the part between the blade and the fence (now a single 0.063" angle, 3x5, 8 inches long) was caught in the blade and shot away toward... me. The force of the impact made me believe I'd have to pull the part out of my guts. Instead I got lucky and it hit and cut into my heavy leather belt. Then it flew across the shop to where I found it after 20 min of searching. It of course was completely distorted. The carbide tip saw blade was missing 3 teeth too...
Bruce A. Frank:
Particularly when using the fence to take a thin slice, the blade, even when set at the correct height, can throw pieces like a spear. My solution was to step to the side at the last few cm of the cut and reach over to the back side of the table to hold onto, with a gloved hand, both the extrusion and the piece being cut off. After the blade cut through I'd hold everything in place, turn off the saw and wait for the blade to coast to a stop. Another thing that worked was to feed that last 1/2 inch or so with a 1 X 2 pusher. The pusher prevented the cut off piece from pitching up and getting thrown by the blade. See the picture for shape of pusher.
Also see http://www.matronics.com/rv-list/hovan/tips/AlumCut.html for how to cut a thinner sheet metal with a router.