Drilling big hole in metal

[country gent]

With a 1/2" pilot hole feed slow and very easy. Your only cutting .060 on a side and it will want to grab and try to thread itself in. Make sure set up is very solid. In the drill press if it has a spindle lock set it to a snug spindle movement

[rancher1913]

we always used plain old water for cooling as we drilled. I was astounded the first time I seen the boss use water that way but it worked good and was easy to clean up.

[Traffer]

we always used plain old water for cooling as we drilled. I was astounded the first time I seen the boss use water that way but it worked good and was easy to clean up.

That is interesting. They recommend water for lube with the little diamond charged dremel type tools and wheels that I get from eBay-China. It is amazing how well water works with these diamond burrs. Far Far better than oil. I have tried it on the lathe also with same great results.
There is one BIG caveat... RUST. It is hard to get all the water out of machines. Nightmare waiting to happen.

[Traffer]

Your drill press probably only goes down to about 300 rpm or so. That is scary fast for drilling steel with big bits. It will chatter and bounce and be a wild ride. Get a good grip on the feed handle and hold it tight. Feed as slow as physically possible and use oil. Don't get scared off by the violence of the project...IT WILL CUT eventually. My first attempt at drilling steel with big bits (going 3" deep into cold rolled steel) was quite an ordeal. I kept trying to modify the bits to take a smaller cut ... it's really hard when the darn thing is spinning so fast. I use a lathe now and slow it down to about 40 rpm with a razor sharp bit. My little lathe still bogs down and trips the breaker. So I now use the "sneak up on the proper size" technique of using progressively bigger bits.

[lightman]

Early on in my life I found a bargain on several different size reamers. These were tapered with the last 1 inch or so being straight. They chuck up in a drill and require less power and muscle than a drill bit. They are brittle and can be broken pretty easily but they make a neat hole with less effort. I have no idea what they would cost but might be worth checking on for a guy that builds lots of stuff.

As far as drill presses go, I wish I had a better one than my old Craftsman. Several years ago I wired a machine shop for a well drilling buddy. He bought out a machine shop and moved all of the equipment. Some of it was huge! One lathe was about 70 feet long and looked like a locomotive. One drill press would handle 48 inch wide material and the column was about 12 inches in diameter. It would reverse and had automatic feed. A nice milling machine fairly makes me drool!

[country gent]

One thing old timers and some shops did with the home drill presses was to replace the step pulleys with a different set of them to slow them down to a useable speed range. They are normally off the shelf pulleys and can be purchased reasonably. Getting the spindle lowest speed to 75-100 rpm from the normal 300-400 rpm can be a big plus. For the added cost of 2 pulleys and possibly a v belt you get a more useable machine longer drill life and more versatility. You don't give up a lot since if the higher speeds are needed the old pulleys and belt can e installed, 1-2 set screws in each pulley.

On the old converted flat belt machines I have also seen 3 and 4 speed transmissions used between motor and drive belt to give speed range changes. Transmissions from older lawnmowers, garden tractors or cars were used here. This gave 3 forward speeds and a reverse on the drill press or machine in addition to the belt drive.

[dogmower]

how precise do the holes need to be? if not, why not just use a torch?

[Three44s]

Reamers breaking like that makes me wonder about how they were manufactured or abused in their former lives. Besides the reamers I have bought (1/2” and 5/8”) my father has acquired perhaps a half dozen large ones with Morse taper drive. I think one has a short chunk missing in one flute and that still does not put it out of service.

My 5/8” car reamer cost right at 55$, nothing to sneeze at but for the value I would do it again in a heart beat. Whether I am using a drill press or my HF 1/2” drill that is geared to 550 rpm free spin I find this reamer to be superior to any other hole enlargement scheme I have tried or seen tried.

I have a old heavy duty drill that needs a new trigger and cord. I should take it and get it rebuilt I know I will spend a tidy sum by doing so. The HF drill contrary to what a lot of folks have felt about it has been very good to me. I have worked to capacity many times but for the cost if I just used it as an overgrown 3/8” it would likely last a long time.

Three44s

[country gent]

We used the 1/2" drill motors for a lot of smaller holes since the speeds of them were closer to what was needed

[Three44s]

how precise do the holes need to be? if not, why not just use a torch?

Trust me, I am no stranger to the “old gas wrench”.

What I get is quick chilled steel (hardened) and having to dig out a die grinder and run a carbide bur to make the to hole more “holy”. I never get what I really want, just a get by.

When I get my tools out and center punch things accurately, start with a good light, small sharp drill bit and step up sizes, don’t hurry, I get something I don’t have to make excuses for and use a bunch of flat washers on.

A year and half ago I fell into a 8800# radial arm drill at an auction. I have not set it up yet (shop space be darned) but when I got it my father asked what was wrong with the cutting torch?

I said well it’s like this .........

Best regards

[Conditor22]

Not knowing how hard the steel is, a shop could punch the holes (I think the machine is called a metal worker)

[Traffer]

One thing old timers and some shops did with the home drill presses was to replace the step pulleys with a different set of them to slow them down to a useable speed range. They are normally off the shelf pulleys and can be purchased reasonably. Getting the spindle lowest speed to 75-100 rpm from the normal 300-400 rpm can be a big plus. For the added cost of 2 pulleys and possibly a v belt you get a more useable machine longer drill life and more versatility. You don't give up a lot since if the higher speeds are needed the old pulleys and belt can e installed, 1-2 set screws in each pulley.

On the old converted flat belt machines I have also seen 3 and 4 speed transmissions used between motor and drive belt to give speed range changes. Transmissions from older lawnmowers, garden tractors or cars were used here. This gave 3 forward speeds and a reverse on the drill press or machine in addition to the belt drive.

Yes, I have been collecting pulleys to eventually build a drill press with the capabilities that I would desire. One of the things I have considered for my little HF benchtop press is a third step pulley. I have two identical HF drill presses... one of which I am planning on converting to an extended tail stock for my lathe. I wont need the pulley so I could use that to gain a x4 speeds by installing it with an additional belt. I believe there is even a convenient place on the press to install it. That would get me under 100 RPM's ...Ideally I would like to get it down to about 10 RPM's.

[JSnover]

That is interesting. They recommend water for lube with the little diamond charged dremel type tools and wheels that I get from eBay-China. It is amazing how well water works with these diamond burrs. Far Far better than oil. I have tried it on the lathe also with same great results.
There is one BIG caveat... RUST. It is hard to get all the water out of machines. Nightmare waiting to happen.

I don't use diamond burrs but every machinist in my shop is issued one of these kits. Coolant is mixed in a 55 gallon drum and you can use any container you like as a reservoir. If it's mixed too light you can get rust but if the instructions are followed and your machine gets normal care - wipe it down and oil it after you finish - you won't have rust (at least we haven't). As with most everything else, your mileage may vary...
https://koolmist.com/lite-duty-coolant-system

[country gent]

That's how our tool room was we had several 55 gallon drums of coolants with hand pumps on them. Water soluble mixed for the mills and mixed for the grinders ( surface, Id OD and Blanchard), black oil, dielectric fluid. With these in a rack on the wall were the labels In our shop ( ISO 9001 and haz mat regs) containers had to be labeled as to what was in them.
Single serving soup cans went for a premium for use with the black oil LOL

[starmac]

I have had to drill lots of 5/8, 3/4 and 1 inch holes in truck frames and thick steel. Where I can I generally use a mag drill and annual cutters, but there are many holes that room doesn't allow it, for those I use a 3/8 bit and the appropiate reamer. These reamers set me back 50 to 60 bucks a piece, but are worth every penny, as far as I am concerned. I have an old slow turning KILL you if you aren't careful but have just used my cordless drill quite a bit too.

[mozeppa]

ii made over 3000 one and a half inch diameter disks from 5/16" thick sheet steel strap ...hard stuff

did it with cutting oil , drill press and YES!....only 3 MILWAUKEE BI-METAL HOLE SAWS. just don't force it.

i've cut 4" holes in 3/4" solid steel plate the same way......yes people ....they WILL work.

[Alan in Vermont]

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.

I spent several years in a couple structural steel fab shops where Hougen Drills were a fact of life. Using their drill motors, mag bases & cutters, under perfect conditions they claimed a 1" hole in 1¼" plate(going from memory here those numbers may be reversed) in 10 seconds. I never had a machined plate to test that claim but I don't doubt it at all.

Any how, for a while I was doing a fair amount of fab work here at home. I have Hougen cutters for thin material, up to 1/4" in sixes from 5/16 to 2" with the appropriate drive arbors so I can run them in the drill press or a hand drill. They also have arbors that have MT shanks for drill presses & mills, with or without coolant feeds. I found cutters from 7/16 to 1 1/16, most of them in 2" cutting length on Ebay for decent prices. I bought a #2 MT arbor to use in my china clone of the Delta 12 or 14 inch drill press. I rarely work in anything greater than 1/2" stock and I can borrow a Hougen mag base if I have to take the drill to the work.

Another tool for really close marking hole locations is an optical center punch, https://www.amazon.com/Grizzly-H5781...l+center+punch If you're doing layout with scribed lines you set the body of this tool roughly over the marked point. Drop in the spotter lens and move the tool body into the crosshairs in the lens are over your marks. Then, hold the tool body firmly in place, remove the lens and replace it with the center punch. One light tap sets a small dimple which you deepen with a regular centerpunch & hammer.

[abunaitoo]

Got it done.
Wasn't to bad.
Moved the belt to the slowest speed, but I think it's still to fast.
Not sure how fast it's spinning.
Couldn't count fast enough
I hope I don't have to drill to many big holes like this.
Project should be done tomorrow.