Drilling big hole in metal

[Alstep]

First piece of advise, WEAR SAFETY GLASSES!

For the situation you describe, I would recommend a hole saw. Use lots of cutting oil and back out to relieve chips often with compressed air. If you don't relieve the chips, the saw will bind up in the hole and break. A hand drill or drill press should be OK for a hole saw for up to 1". Don't go over 250 to 350 RPM. The bigger the hole, the slower the RPM. You're going to be awhile getting through 1/2" of metal.

A better alternative would be a heavy duty magnetic base drill setup.

With regular drill bits, don't go over 1/2" with a hand drill, the torque will rip the drill right out of your grip. Harbor freight drill presses don't cut the mustard either. For bigger holes, I drill in increments till I reach the size I need. For that, a Bridgeport mill with the work well clamped is a minimum setup.

I give this advise after a lifetime working as a machinist in the metal working trades. Work safe & good luck.

[Jeff Michel]

Take it to a machine shop and pay them. Less stress, probably less money spent and more predicable results. I have a fairly complete machine shop but I don't have a big burn table or a water jet cutter. The man does down the road, I let him do the heavy accurate cutting and while he does that, I work on other aspect of the project. FWIW, I agree that doing it by hand isn't probably the best course safety wise, it takes a pretty good man to handle the torque from a 1/2 inch drill and a big bit. Good luck and be safe.

[abunaitoo]

I have a drill press.
That's how i drilled the 1/2 holes.
I'll have to see how slow i can get it to go.
The reamer idea sounds good.
I'll have to look for some.
I have a metal hole saw set, but it's not that great with thick metal.
The one that has carbide cutters would be great, but hard to find here.
Also have a Unibit set. Might see if that would work.
Going to home depot tomorrow to see what the have.
I've always wanted one of those magnet drill press.
So expensive.
Have a torch set, but holes have to be round.
I'm not that good.

[GregLaROCHE]

I’ve drilled 5/8” holes in 1/2” SS with a hand drill. Not fun, but it can be done. Make sure your bits are sharpened correctly. Even if they are new, if they came from China they may not be right. This a good video explaining how drill bits work and how to sharpen them correctly. If the quality of your drill bits isn’t up to it, I sugget a machine shop or carbide hole saw.

https://youtu.be/r8oORR6jyh8

[Traffer]

I have a drill press.
That's how i drilled the 1/2 holes.
I'll have to see how slow i can get it to go.
The reamer idea sounds good.
I'll have to look for some.
I have a metal hole saw set, but it's not that great with thick metal.
The one that has carbide cutters would be great, but hard to find here.
Also have a Unibit set. Might see if that would work.
Going to home depot tomorrow to see what the have.
I've always wanted one of those magnet drill press.
So expensive.
Have a torch set, but holes have to be round.
I'm not that good.

I got a set of Silver and Deming Drill bits from Harbor Freight for $28.. 9/16 in., 5/8 in., 11/16 in., 3/4 in., 13/16 in., 7/8 in., 15/16 in., 1 in. They cost me $28 on sale. If you start with a smaller drill and work up to your size holes and use cutting oil they will cut the holes for you. I have used them many times to drill deep into steel, I used then to hollow out 1" cold rolled steel to 13/16" then tap to 7/8 14 to make holders for standard reloading dies, I used a cheap HF table top drill press the first time, Went from 1/4" hole right to the 13/16"...it took a long time... so I started doing the bigger and bigger hole thing...
When you do it leave the belt kind of loose and clamp down the work, you don't want it to start spinning on you. Use safety glasses, leather gloves and feed slowly...you may have to sharpen your bits a couple times while going through if they get knarled up on you. The kind of lose belt keeps the bit from spinning in the chuck, belt will slip first.
Good luck

[rancher1913]

https://www.ohiopowertool.com/p-8478...CABEgJVgvD_BwE

this is the type of bit that works really good for holes in thicker metal. a rental yard should have everything you need.

[RU shooter]

As another member said find a small fabrication or machine shop . I have a waterjet that would make quick work out if it but the shipping to and from where your at would be costly

[EDG]

I have drilled maybe a million holes in 1" plate using radial arm drill press.
I would take your work to a machine shop.
You should center punch where you want the holes and let a machinist drill them. Both pieces of metal you are drilling are not very thick for such a large drill and will tend to grab when exiting the back side.

[JSnover]

Do you have or have access to a cutting torch? I use mine for stuff like this all the time, even though I own a drill press and an extensive drill bit collection, while not as precise as a drill bit it will get the job done and save some time in the process. With some practice and a little grinder/file work you can cut good round holes. I can’t believe I’m the first to suggest this, maybe I’ve been doing it wrong?

When I worked at the Juniata locomotive shop an oxy-acetylene torch was the preferred 'drill' for any hole over 1/2"

[Ole Joe Clarke]

Take your piece of material and go to the nearest small machine shop. Some of them will help out an individual, and they have the proper drill bits, drill presses and/or milling machine to do the job. You will save time and the hassle of trying to do it with the wrong tools. The cost to you will probably be well worth it.

Have a blessed day,

Leon

[country gent]

The difference between the home drill presses and industrial grade gear head drill presses is like night and day. We would drill scrap exhaust holes in die shoes up to 3" in the big drill press at work. This machine was gear head and lowest rpm was 12 rpm. I believe the fasted was around 800 rpm. Power feed. 10 HP motor. Forward and reverse. You had to securely clamp everything down to the table this machine didn't stall out and holding the part by hand would suck you right into it. With the right pilot hole this machine would drill a 3" hole the depth of the drill. When the feed was engaged it cut very cleanly and gave a good chip curl. This machine had a #5 morse taper in the spindle. It would do bigger as well but 3" was the biggest drill we had.

When drilling holes a solid set up, correct pilot hole, good cutting oil. Correct speeds and feeds goes along ways. When drilling roll shirt sleeves up, safety glasses, a ball cap or something to contain hair and no loose clothing. A drill press spindle will grab a few hairs then more and finish when your scalped. same with gloves or loose clothing it grabs and sucks you in.

[Conditor22]

How many and how accurate do the holes need to be?

I'm no machinist, I would drill them out to 1/2 then enlarge to 5/8 or 3/4 so the big bits aren't having to hog out as much.

[JonB_in_Glencoe]

I got a set of Silver and Deming Drill bits from Harbor Freight for $28.. 9/16 in., 5/8 in., 11/16 in., 3/4 in., 13/16 in., 7/8 in., 15/16 in., 1 in. They cost me $28 on sale. If you start with a smaller drill and work up to your size holes and use cutting oil they will cut the holes for you. I have used them many times to drill ...

>>>SNIP

I have the same set of bits, and have drilled some large holes in 3/8" thick steel plate...just follow the directions that Traffer layed out.

[GregLaROCHE]

I’m not a machinist, but have had a lot of life experience drilling holes in steel. Mostly with under powered drill motors and presses. I’ve found cobalt drills work better than HSS. If you have a pilot hole and the drill has enough powder, you can go right through in one pass. If the equipment is not the best, that is when working up in sizes comes into play.

[CastingFool]

I don't know how large the pieces you need to drill, but if possible, make sure your pieces are well clamped down

[popper]

Be sure to bolt that sucker down when drilling, whatever you use.

[country gent]

One thing we did when using a hole saw to help it cut clean. We layed out the hole center then with dividers the actual edge of the hole and 4 -8 small holes 3/16-1/4" so that hole edge was on the edge of the actual hole. With these holes the saw could clear chips easier these holes allowed chips to drop out. they also gave a place to pry / grip when pilling the slug out. Never cared for the finish, size or the way a hole saw cuts when working in metal.

[country gent]

If you cant clamp / bolt piece down a well placed bolt thru the table slots for it to bear against will help with it wanting to spin

[abunaitoo]

https://www.ohiopowertool.com/p-8478...CABEgJVgvD_BwE

this is the type of bit that works really good for holes in thicker metal. a rental yard should have everything you need.

Was looking at bits like this.
I'll probably look for a set later.
If I can find them for cheap.

[abunaitoo]

Went to home depot and got two drill bits.
I'l move the belt on the drill press to the slowest setting.
Lots of cutting oil.
1/2" hole already drilled for the 5/8" hole.
We'll see how it goes.