Use hole saw slow with oil. Easy if you can clamp it in place and have a drill press. My buddy manages a machine shop, that is exactly how the professionals do it. I had to get twenty holes drilled in raised floor tiles. Burnt up $40 worth of hole saws trying to do it by hand. Brought them to him, $100 & 24 hours later I had them done perfectly. They drilled them really, really slow that is the key to not melting the whole saws.

quote:

Originally posted by Skins2881:
Use hole saw slow with oil. Easy if you can clamp it in place and have a drill press. My buddy manages a machine shop, that is exactly how the professionals do it. I had to get twenty holes drilled in raised floor tiles. Burnt up $40 worth of hole saws trying to do it by hand. Brought them to him, $100 & 24 hours later I had them done perfectly. They drilled them really, really slow that is the key to not melting the whole saws.

^^^Exactly. Holesaws and hand drills are a recipe for disaster. Good bimetal holesaws (not the cheesy ones made out of spring steel), drill press only, on slowest speed, work clamped securely, lotsa oil/lubricant. Lennox and Milwaukee make good homeowner grade holesaws.

Center punch the material.
Clamp it down in the drill press so it won't spin.
Then using various drills keep stepping up till you get to 3/4. You could step up at 1/8 increments. Use oil on the bits and and slow the speed down when you get to a 1/2 inch.
You should put a piece of something sacrificial under the piece your cutting so you don't drill into the table.
When you're done deburr the hole on both sides.

Depending on how perfect the finished hole needs to be, you could drill around the circumference of the hole you want with a 1/8" to 3/16" drill, then finish with a rat tail file or a burr.

Or if you wanted to be really fast....

dont use pilot hole larger then the flats on the 3/4 bit or your going to end up with an 8 sided hole probably a 1/4 to 5/15 hole is all that is needed. clamp it and use some cutting oil go slow. I do it all the time with my home shop 1/4 inch is nothing.

Annular cutter. That's the right tool for the job.

The carbide slugger cutters are decent for the price, and last OK, plus you don't need a special arbor.

https://www.amazon.com/Jancy-S...129&s=gateway&sr=8-2

^^^^

That's what I use. In a Rotabroach. Cuts perfect holes through any thickness in relatively short order.

quote:

Originally posted by ffips:
As mentioned, block and clamp. Don't be afraid to use multiple bit sizes between 1/4 and 3/4. Lubrication is also a good idea. Let the bits do the work.

This would be my recommendation also. Multiple sizes to get to 3/4”

Everyone has given good advice, but mine is the best. Find an AP or API round that will give the approx diameter that you need and then purchase it and the firearm to go with it. Sight it in and set it up and start making holes. I can't guarantee the pieces will be usable but you will have fun in the process, you will have metal plate with holes in it, so technically you were trying....

You, sir, are a genius. Truly, a steely eyed missile man.

Hell, I used to think I was pretty experienced drilling holes in metal stock but after reading all of this...I don't know jack shit.

Great thread.

Some of you guys are nuts. lovable, but nuts.
I would not hesitate to drill a 3/4" hole in 1/4" mild steel plate using a drill press and a decent bit. clamp it down, keep it cool, adjust your spindle speed to slow and have fun. A pilot hole with a smaller size is easy and will improve accuracy a tiny bit.
Step drills are in general junk. A hole saw is not needed at this diameter and is not as effective. Of course if you just need a hole a plasma cutter is the quick answer, but really doubt that's what you are thinking or likely have. There is no need to farm this out.
I've done this thousands of times.

Drill 1/2" hole then use a reamer.
https://drillsandcutters.com/3...YEAQYAyABEgKEW_D_BwE

quote:

Some of you guys are nuts. lovable, but nuts.
I would not hesitate to drill a 3/4" hole in 1/4" mild steel

No kidding. I'd have had it drilled and done in half the time that's been spent talking about it.

quote:

Originally posted by trapper189:

quote:

Some of you guys are nuts. lovable, but nuts.
I would not hesitate to drill a 3/4" hole in 1/4" mild steel

No kidding. I'd have had it drilled and done in half the time that's been spent talking about it.

Hell I'd do it (and have) with either 1/2" drill bit plus step bit or hole saw and a cordless drill. May not be the 'best' way but I've got it done before.

You guys are trying to take the fun out of it.

Safecracking? We have an app, or a member, for that.