drilling large holes in steel with a hand drill?

md21722 · Jun 28, 2016

Hi,

I am somewhat new to using hand drills to drill steel. I was using the drill speed charts and found that bits were getting hot enough to smoke heavy sulphur based cutting oil. As an example, I was trying to drill a 1/2" hole through ~ 3/16" thick low carbon steel at 700 RPM. The bits always caught at the end throwing the drill around and often chipping the bit.

After trial and error, I tried drilling much slower than the drill speed charts would suggest. The results were amazing. Bits seem to last longer and they don't bind at the end.

My theory is that its almost impossible to apply enough pressure with a pistol grip drill to justify the higher speeds.

I am wondering if my theory is correct.

If anyone wants to entertain me some more, I have been using air drills for this work. Most of the major players offer drills in 0.4, 0.6, and 0.9 HP. I am wondering why this is necessary for hand drills, because its hard to apply enough force to warrant all the power? Do you really need a 0.9HP hand drill? If it catches I would think all its going to do is try to break your wrist faster. But clearly folks like Sioux and Dotco make these for a reason.

Thanks!

13engines · Jun 28, 2016

You're going to have a hell of a time pushing a 1/2 drill through steel with a hand drill. Try drilling with a smaller drill first. Use a drill just a little bigger than the chisel tip on the large drill. You may even go up in three steps for large drills. I've found even trying to drill 1/4 with a hand drill is best started with something smaller. 118 degree bits are going to break thru less violently than 135 degree. Still it's always a trick handling the breakthrough. Plus half the time the bit spins in the chuck too. Anyway... start smaller.

Steve in SoCal · Jun 28, 2016

I know the routine all too well. 3/16 is too thin for a mag drill but, if you can slip a 3/8 or even 1/4 plate behind it a mag would be best. My 1/2" Milwaukee hand drill is 12a, way more that a .9 HP air drill, it will break a wrist if it binds. I use my mag drill whenever possible. You may try hole saws, they take far less pressure and only remove the metal in the kerf.

Steve

L Vanice · Jun 28, 2016

Split point bits help. You can get bits with three flats on the shank to prevent spinning in the chuck. The old Black & Decker Bullet Point bits were made for drilling metal with hand-held drill motors. I liked them. The current version is the Dewalt Pilot Point, which are made in China.

My Milwaukee Hole Hawg has a huge side handle to take the torque.

Larry

Danny VanVoorn · Jun 28, 2016

In order to calculate speed you will have to add the feed and that goes out the window when drilling by hand. The best you can do is slow it down enough to see you have sufficient chip load and deal with the break through. There are proper ways to grind a drill bit that will minimize the grabbing at the break through point but that is a different topic. HP should be pretty self explanatory, try to maintain a constant RPM with out enough and see what I mean.
Dan

md21722 · Jun 28, 2016

Good feedback.

I had originally started with a 1/8" pilot hole and opened it up to 5/16". Then I tried a larger bit that was maybe 1/16" less than the final size. This was a mistake as I snapped a Norseman 31/64" drill bit in half immediately. This was a standard black & gold mechanic/ maintenance length drill (not cobalt).

So I decided to go smaller than 1/16". But then the problem was still trying to get it to drill on center so I didn't end up with an oblong hole.

But honestly going pretty darned slow I can drill a 9/16" off a 1/8" pilot hole. It takes some time, but it works and the bits don't bind. I think the 9/16" is 135 degree, but all the other larger sizes I'm using are 118 degree Chicago Latrobe bright finish or black oxide finish. And this way the hole is always on center.

It's almost as though the faster you go with the hand drill, the more it vibrates and heats up rather than cut the metal so going slow is king.

I have been using an old Atlas Copco 1/2" 700 RPM drill with a Rohm chuck that I got for cheap. No spun bits on it. The Norseman have the 3 flats on the shank, the C-L bits do not.

md21722 · Jun 28, 2016

Danny VanVoorn said:
In order to calculate speed you will have to add the feed and that goes out the window when drilling by hand. The best you can do is slow it down enough to see you have sufficient chip load and deal with the break through. There are proper ways to grind a drill bit that will minimize the grabbing at the break through point but that is a different topic. HP should be pretty self explanatory, try to maintain a constant RPM with out enough and see what I mean.
Dan

Thank Dan! Since the Atlas Copco I'm using can maintain any reasonable speed I want without stalling I guess its powerful enough! I believe its a 0.6 HP and has a nice teaser trigger.

JST · Jun 28, 2016

My advice is NOT TO step up in size. Certainly not in small increments.

Just do a pilot hole, and then, for 1/2", go for it.

I found that stepping up, there was way too much tendency to grab, "screw-in", and jam. Jamming means a heck of a wrench on your wrists, which will just wear you out trying to brace for it.

As for the jamming and screw-in when you break through, if you let up on the "feed", and speed up the rpm, you usually will get away with it just because the inertia of the drill motor mass will overcome the small resistance of the "fins" at breakout, IF you feed slow so they are not too big. Often that nearly amounts to holding the drill back....

And, about the drill motor.... go get the biggest one you can find. Yes it's heavy.... but it will generally do the "inertia thing" better, and it generally gives you better leverage against torque due to a double handle, side bar handle, etc.

Yes, hole saws, the good kind, at least the bimetal ones, better the real ones of HSS with a bar guide, not a drill. Take out the starter drill if the saw has one,and put in a straight bar. Drill that size first, then use the hole saw with the bar.

Chip Chester · Jun 28, 2016

Yes, once you get above maybe 3/8", it's impossible to push too hard.
I used to show high school club kids how to use a drill, most for their first time. I always had them watch their chips. If they weren't making chips, they were either not pushing hard enough, and/or going at too high RPMs. Basically generating heat and dulling the bit, instead of drilling.

And that's why they call me...
Chip

md21722 · Jun 28, 2016

Chip Chester said:
Yes, once you get above maybe 3/8", it's impossible to push too hard.
I used to show high school club kids how to use a drill, most for their first time. I always had them watch their chips. If they weren't making chips, they were either not pushing hard enough, and/or going at too high RPMs. Basically generating heat and dulling the bit, instead of drilling.

And that's why they call me...
Chip

LOL awesome Chip!

DDoug · Jun 28, 2016

I took one of those all metal, 3/4" chuck mankiller
Hand drills.
I welded up a trailer jack with a v-block, hose clamps
To attach the drill.
Replaced the wheel on the jack bottom with a small
Angle iron clip.

I bolt or clamp it where needed and have crank feed,
And no worries if it grabs.

Drilled 1" dia.. holes up into a 24" i-beam header with it.

Bondo · Jun 28, 2016

If you have access to a mag drill then just clamp a piece of 1/2 to it to mag to.

For 1/2 " drill bit I use a 1/8 pilot and then go to 1/2. Use 135 degree split points designed for stainless and they work great, less material being removed at one time.

I like using the hougen sheet metal cutters. They go down to 1/4 " and only good up to 1/4" but they work great.

Mike C. · Jun 28, 2016

Yes, it is impossible to put enough pressure on a hand drill to get a proper chip unless you weigh about 1000lbs and can get all your weight on the drill. Drilling big holes with a hand drill motor just flat sucks, no way around it.

Many years ago, I worked as a tool trailer guy for an industrial service company that did repair and maintenance in the cement plant field. Bunch of big burly ironworkers that could swing a 10lb beater (sledge hammer with a foot long handle) with one hand like it was a 4oz ball peen. The one thing in that tool trailer they were unanimously terrified of was a big old 3hp pneumatic reamer motor.

ManualEd · Jun 28, 2016

Find a step drill that has 3/16 high steps and fly at er.

You'll drill your half inch hole in 10 seconds with little effort.

It'll chamfer your hole at the same time.

JST · Jun 28, 2016

ManualEd said:
Find a step drill that has 3/16 high steps and fly at er.

You'll drill your half inch hole in 10 seconds with little effort.

It'll chamfer your hole at the same time.

For relatively thin metal this is THE best idea. They work well, and go up to around 3/4" anyway, maybe 1". They give the effect of step drilling, but they guide the drill and cut in such a way that they don't pull in etc.

But they stop being good somewhere around 3/16" because the steps are about that long,and you lose a good bit of the advantage if you have 2 steps cutting at once.

And, they usually leave one hell of a big burr on the breakout side.

But definitely worth using where they are usable.

Long Tom · Jun 29, 2016

L Vanice said:
Split point bits help. You can get bits with three flats on the shank to prevent spinning in the chuck. The old Black & Decker Bullet Point bits were made for drilling metal with hand-held drill motors. I liked them. The current version is the Dewalt Pilot Point, which are made in China.

My Milwaukee Hole Hawg has a huge side handle to take the torque.

Larry

A Hole Hawg will twist you up if you let it. Heck, my Magnum Holeshooter has hurt me a few times, side handle and all.

You can learn a lot about feed, speed, and rigidity drilling big holes with a hand drill!

rmcphearson · Jun 29, 2016

There is some type of improved hole saw/drill meant for hand held drills that makes drilling large holes a breeze. I saw one recently and can't remember what they are called! Someone help me out here.

rbent · Jun 29, 2016

I use mainly step bits for larger holes with a cordless drill, for regular twist drills, drill the pilot then use your 1/2" drill. If I can't get it with the mag drill, I use a drill with a clutch if I have a choice. At my last place I had some Hilti hammer drills that had a non adjustable mercy clutch in them, they got used when cordless ones were to small. I like the clutch rather then trying to break a wrist.

Cutting fluid sure helps when doing by hand too, I use CRC True Tap EV.

Jimmy_pop · Jun 29, 2016

Use a punch and hammer to mark your hole for the 1/8" pilot hole. Then use a unibit with the hand drill. 3/16 is easy. Depending on how many you need to do, you could probably skip the pilot hole. This is easy work with a unibit.

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Scottl · Jun 29, 2016

Drilling large holes with a hand held drill can be an exercise in frustration. Here's what i have found.

The slower the better, and a 1/2" electric drill is the minimum that should be used on holes in steel over 3/8". Milwaukee used to make some geared down 1/2" drills that had enough torque to sprain a wrist if the user got careless. They were usually used with a side handle. I'm not sure how good the newer one are.

Flats on the drill shank are very important with hand held drills as even the best chucks can slip when the bit snags. I have had very good luck with the Trinado bits from Enco. They have three flats on the shank and a proper point for steel.

The best bet for drilling fairly thin steel with a hand held drill are good quality step drills used as slow as possible with good cutting oil. I have drilled some serious holes in square tubing that way using only a 3/8" electric drill. The steps and the single point make things more controllable than twist drills. The ones from HF will work in a pinch but they leave heavy burrs.

If both sides of the work are accessible the step drill does a nice job of deburring and if you are real careful it is possible to drill from both sides on material thicker than the step length.

drilling large holes in steel with a hand drill?

Plastic

Stainless

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Diamond

Titanium

Plastic

Plastic

Diamond

Diamond

Plastic

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Stainless

Diamond

Stainless

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