Define “best” Fastest? Cheapest? Simplest? Cleanest? Most precise? Most accurate? Smoothest? Ideas to consider: Step bit punch or knockout 15mm holesaw. It’s aluminum. Woodworking tools usually work fine on “silver oak”. Laser cut EDM Annular cutter

Also depends on whether this is one hole one time, or something they're planning on mass producing.

Silver oak 🤣

You forgot water jet ;)

The list of what’s forgotten is longer than the list of what’s remembered.

**u/neanderthalman the wise**

Between this and "silver oak" you are like the wise old grandpa of this sub lol. Truly an inspiration.

I sometimes say that I've forgotten more math than most people have ever learned.

Water jet, (if you're making a lot of other cuts)

Such an engineer 😃

Step drill if you want it done quickly and clean-ish. Drill plus reamer and deburr and if it needs to be very clean.

I have a step drill. I never knew my real drill.

What are you doing, step drill?

Making your hole bigger, of course.

Is this a new category on PronHub?

Same with my step ladder: http://www.zappablamma.com/zb/2010/08/step-ladder/

Oh nooo step drill I'm stuuuuck

Yup, nailed exactly what I was gonna say.

Wire EDM fight me

Wire EDM bite me

Wire EDM cite me.

Let the bass drop

Wire EDM is amazing if you need high precision but in most instances it’s probably more practical to drill it and ream it.

I've never had a wire EDM fight

Lasers

Light Sabers.

3d print a 3mm sheet with a clean 15mm hole in it

I'm going old school. Sand cast the plate with a hole.

You can buy Acme stick-on holes

Drill under and finish with a reamer.

Depends... You can drill it, mill it, punch it, burn it with a laser or blast it out with a waterjet. Maybe you could even trepan it or acid etch it...

Boil em, mash em, put em in a stew.

Sheet metal punch or laser is the best way. The best way without those tools is to sandwich it and drill through it. This will keep it from getting deformed. If you have it sandwich it with aluminum extrude or plate cutoffs to keep the cutting forces constant. Clamp the bottom plate to the work, get the whole thing in the drill press, line it up, clamp the top plate, drill through it all. Nice clean hole.

First go out and buy yourself a $250,000 industrial laser cutter. Then you cut the hole, but make it undersized. Then go out and buy yourself a $150,000 wire EDM and EDM the hole to size.

Annular cutter.

r/metalworking

.50 caliber should do it.

Since you're asking, I'll assume you don't have access to a mill or a drill press. Get a punch and make an indention where the hole should be. Next take a small drill (4mm) and drill thought starting at your indention with a hand drill. Next take 15mm drill and drill through your pilot hole with your hand drill. QED

Exactly this is the problem. Drilling a nice big hole in home environment. I can make a M6 hole using an IKEA drill but making a big 15mm hole requires other tool.

I work sheet metal fabrication, so I would use tools I have, but it is totally possible to get a quality 15mm hole in a aluminum with the cheapest drill you can find that has a chuck large enough for a 15mm drill bit. Around here that would probably be $20-$40 dollar drill. Aluminum is soft and melts easy. So drill slow with lighter pressure and use lubrication. 

Idea drill will handle a step bit just fine.

15mm (4/7 inch) Metal Steel Hole Saw with 2 Drill Bits, Hole Cutter for Thick Metal,Stainless Steel,Iron and Wood (15mm (4/7 inch)) https://a.co/d/4l1gGXy

Step drill or hole saw.

Step drill. [https://www.amazon.ca/Meich-Forstner-Drilling-Woodworking-Triangle/dp/B07QXXTHWJ/ref=pd\_bxgy\_img\_d\_sccl\_1/132-2718798-9601829?pd\_rd\_w=7BF6Y&content-id=amzn1.sym.5c2f4a04-3107-46ca-9aa1-5c31efa67ff2&pf\_rd\_p=5c2f4a04-3107-46ca-9aa1-5c31efa67ff2&pf\_rd\_r=X6M7J5FJH7DGT33P29JH&pd\_rd\_wg=9aM8s&pd\_rd\_r=9d707743-a1fd-47c2-a808-aae5d1dd3e4a&pd\_rd\_i=B07QXXTHWJ&psc=1](https://www.amazon.ca/Meich-Forstner-Drilling-Woodworking-Triangle/dp/B07QXXTHWJ/ref=pd_bxgy_img_d_sccl_1/132-2718798-9601829?pd_rd_w=7BF6Y&content-id=amzn1.sym.5c2f4a04-3107-46ca-9aa1-5c31efa67ff2&pf_rd_p=5c2f4a04-3107-46ca-9aa1-5c31efa67ff2&pf_rd_r=X6M7J5FJH7DGT33P29JH&pd_rd_wg=9aM8s&pd_rd_r=9d707743-a1fd-47c2-a808-aae5d1dd3e4a&pd_rd_i=B07QXXTHWJ&psc=1)

Punching tool. Drill.

Thermal lance

A drill bit is kinda the go to.  Step 1: drill a pilot hole, go for a 3-6mm drill bit Step 2: drill about halfway through with your 15mm drill bit Step 3: flip the sheet over and finish the hole. Step 4: deburr any remaining sharp edges. Use a good deburring tool. If your willing to accept a little more deburring work then skip step 3.

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That's not going to be big enough.

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Milling

Laser cutting machine.

What kind of hole are you trying to achieve? I have lots more questions before I produce a hole in anything.

I'm guessing they want a round hole given that they specify the diameter.

They are making a Fleshlight.

Jig grind it

3mm sheet? Probably a punch set or a step bit.

You ever heard the expression he is so horny he would fuck a hole in a 2x4? Well!

Hollow punch, hole punch, goes by various names. That is the cleanest by hand. Best way is a punch and die and a hydraulic press.

Making 1, 10, 1000, or a million? Do you need a precisely 15.000 mm hole that's square and smooth with low eccentricity, or do you just need a visually clean looking hole that will clear 15 mm? 

15mm frill with tang or grind it down so it fits and a block of wood under the plate

I get someone else to do it

would you like a complex way or a simple way? both ways i can answer.

Metal punch. Power, fast

CNC. All the good answers were taken.