40 mm hole saw in a drill press for cutting aluminum?

While I love annular cutters for use in the lathe and BP the 3/4" shank may be a problem for the OPs requirements so a simple hole saw such as a Starrett bi-metal  hole saw would be more than adequate. Such as

.

Thanks. I thought carbide-tipped would be necessary, but then figured bi-metal would work. I looked at Starrett and Morse. I ordered two like your suggestion. One Lenox with integrated arbor, and the other a Dewalt 7/16 inch shank arbor plus a Morse saw. Local stores don't carry 1-9/16" diameter saws but no matter, already delivered.

Hand-held hole saws up to 4" worked well enough for me when I was installing conduit into steel control boxes. Use a slow drill, like

500 RPM.

  My wrists won't take it any more ...

IIRC the magnetic-base drill wouldn't hold reliably on vertical painted sheet metal and the hydraulic Greenlee hole punch was even more heavy and awkward than the D-handled Milwaukee drill and hole saw.

That was one of the difficult manual metalworking tasks that prompted me to buy a milling machine.

Milling machine to make holes in wall-mounted electrical boxes? I'd love to see that setup.

I progressed to building more sophisticated equipment for less hostile workplaces; no more wash-downs or oil spray.

Since these electronic enclosures didn't need to be liquid tight I could make control panels flat and small enough to mill.

I still cut large round holes for fans, and for analog panel meters when I need their fast response more than accuracy, like on the input to an MPPT solar controller.

"Liquid tight stainless control boxes for washdowns" used to be my middle name when I had a ton of work at pharmaceutical plants. Then, "oil tight" became a big issue on machines that drilled & tapped big holes in cast iron - the boxes I was replacing would fill with oil and iron "filings" that were abrasive enough that they'd wear the insulation off the 50-year-old wiring.

Still, I never had a problem with the hydraulic punches, even for 4-inch conduit (though I'd get someone to help with those).

That MPPT stuff is pretty cool, and area in which I've yet to tread.

Of course I practiced using a hole saw by drilling through wood. The plug (the cut out part) gets stuck in the hole saw. I might cut through

1/8" thick aluminum for practice, too.

Will 3/8" thick aluminum get stuck in the hole saw?

Also, for cutting fluid, I have these choices... WD-40, silicon spray, Teflon spray, and the combination of silicon and Teflon, and 3-1 sewing machine oil. Or I could go pick up some cutting fluid from Home Depot if it helps for my 2 cut task.

If the hole saw cuts, it will cut a quarter inch just fine. But, a hole saw in a drill press (vertical downward press) doesn't clear chips from the cut, you have to back out and apply suction, or a brush, or otherwise get the junk out of the kerf. Hole saws work better with horizontal boring, or an active flood of coolant, or lots of back-off-and-clear-waste.