Drill bits and drilling thick steel

[bc]

Hello guys. Got some projects coming up that involve drilling some steel from 1/4 to 1/2" thick with either 1/2" or 3/8" holes. Got the issue broke down into 6 questions. Just looking for opinions and experience.

1. Type of drill bit. I've bought a bunch from black oxide, titanium, cobalt, and maybe some others over time. So far the black oxide and titanium have been a waste of money except for wood. Seems like cobalt stays sharper and cuts longer. I've got Ridgid and Menard's masterforce in cobalt with the Ridgid being best but more expensive.

2. Speed of drilling. Bits claim to be hss, high speed steel, but my experience from heavy duty shop drills with big bits was to go slow with a low rpm. Not sure how slow.

3. Pressure needed. My experience with the big presses was to use a lot of pressure but hard to do with a hand drill and sometimes it just dulls the bit.

4. Cutting oil. Have used oil on a heavy duty shop press with success on big bits but when drilling by hand or with my cheap craftsman wood drill press with changeable speeds, sometimes the oil just stops the bit from cutting and it just spins. That craftsman press also bogs down real easy under pressure.

5. How to deal with that point of bit breakthrough where it grabs the bit and torques my wrist or spins the metal. With a big press I used to lighten up the pressure just as it gets to that point and then push down hard to cut on through.

6. I've got a couple bit sharpeners and have sharpened them by hand with varied success. Sometimes the point doesn't come out right or the angle of the cutting edges, and sometimes they will drill a dimple the size of the bit and then quit.

So anyway, I'm not sure what works best to hand drill 1/2" holes in mild steel some of which isn't so mild. I've been keeping an eye on auctions looking for an old heavy duty stand up drill press.

Thanks for your help and advice.

 

[SVcummins]

Slow speed and a good amount of pressure i found
antifreeze is good for cutting fluid tap magic is good

 

[wore out]

Start with a small bit and upsize in one or two or more steps to the desired size.

And, for gosh sakes, securely clamp down the workpiece before you get a broken wrist or a hand slash by spinning metal.

 

[Janicholson]

Real drills are not cheap. a good 1/2 inch bit should cost $10.00 OR MORE. Old buick bumpers shaped to resemble drills are worthless. Use antifreeze, cutting oil, tap magic or 3 n 1 oil for lube. Drill a 3/16" hole first!! Drill at 1/2 the speed of a 3/8 hand drill motor, or full speed of a real 1/2" hand drill. 500 rpm max for the full size hole. Jim
ONE

 

[Charles in Aus.]

I needed to drill 3/4" holes in half inch steel for implement pins and found the drills way too expensive .
I had incredible success with a tungsten carbide tipped hole saw . I would not have believed it if I hadn't cut them myself . 10 holes in half inch steel from an 18 dollar saw , no teeth shed , cut through steadily and cleanly and all with a little 1/4 hp drill press with water as a coolant .

 

[kcm.MN]

<3. [i:4fac1ed2c7]Pressure needed. My experience with the big presses was to use a lot of pressure but hard to do with a hand drill and sometimes it just dulls the bit[/i:4fac1ed2c7].>

Think of a chainsaw. If your chain isn't sharp, you're not gonna do much cutting. Same thing here. You need SHARP bits. But you also need to understand how to sharpen a drill bit so that you can check whether your store-bought bit(s) are sharpened correctly. I have bought bits that had a neutral grind - meaning, the only way they'd go into wood is if the wood was rotten! Buy quality bits -- you'll swear a lot less!!

<5. [i:4fac1ed2c7]How to deal with that point of bit breakthrough where it grabs the bit and torques my wrist or spins the metal. With a big press I used to lighten up the pressure just as it gets to that point and then push down hard to cut on through[/i:4fac1ed2c7].>

There's two ways to help with this issue. If possible, you can drill from both sides of the hole. As soon as the bit starts to peek through the other side, finish drilling from the 2nd side.

Another thought is to put some backer material behind your work. If you're drilling wood, use wood. If you're drilling metal, then try to use metal. If grabbing is a serious issue to your project/conditions, then tack weld a piece of scrap to the back if possible.

Otherwise, when you get near the other side, use EXTREMELY light pressure with a sharp bit and lots of cutting oil, or ???

<6. [i:4fac1ed2c7]I've got a couple bit sharpeners and have sharpened them by hand with varied success. Sometimes the point doesn't come out right or the angle of the cutting edges, and sometimes they will drill a dimple the size of the bit and then quit[/i:4fac1ed2c7].>

As I said, study up and understand how drill bits should be sharpened. Understand what different kinds of bits are meant for and how to sharpen each one. It's a science. There are lots of folks who can get by quite well just sharpening by hand. I used to be one of those, but not anymore. Don't know what happened, but I lost that magic. But seriously, if you drill regularly and especially if you sharpen your own bits, do LOTS of research on the subject, including the metallurgy of bits and the uses for each type. Sorry, no quick answers here.

 

[Steve@Advance]

Most questions have been covered.

How many holes do you need drilled?

Hand drilling 1/2" holes in steel sucks, no matter how you go about it.

Look at it this way, the black oxide drills will do the job as long as they are quality drills. No advantage in buying the expensive ones and wrecking them with a hand drill.

If any way to fit it in the budget, one of these will save a lot of drill bits, drill straight, speed controlled, break through controlled, safer, easier holes, and many tens of thousand of holes, even though it is a Chinese piece of junk!
Harbor Freight

 

[DavidP,South Wales]

Don’t know if you have the same name on your side of the pond but I
have a Rota-broach drill made by Evolution. This is a compact unit
with an electrically switched magnet. It has been nothing short of
fantastic whether drilling small or large up to about inch and a quarter
so far. Well worth buying one if you have the work for it or can you
hire one perhaps?
You are ok with electric hand drill speeds up to about 3/8” but over
that you need to be slowing down. Anything over 1/2” needs to be
held in a sound drill stand where moderate force can be applied and
keep it straight. At these sizes the drill held by hand will chatter and
damage you and the bit.
Use plenty of cutting oil that is good quality to keep the bit cool. Just
as a reminder do not use lubricating oil! That certainly won’t work.
If you sharpen bits by hand on a bench grinder, with the greates of
respect, do you know what you are trying to achieve? The angle at
the drill point must be around 120 degrees and equal with the tip
central. You must also have clearance angles on the lans?
Hopefully this will be of some help.
DavidP, South Wales

 

[Pete in Holland MI]

Black oxide and titanium are only coatings. Go to a machine store and buy good bits. All high speed steels are not the
same. You have to pay for good steel. Big box stores won't have good bits. They're driven on price & material gimics.

Drills larger than 3/8", drill a pilot hole about 1/8" diameter first. That web on the bigger drills needs to be forced
thru the steel. A pilot drill has a finer web, and eliminates some of the force needed on the bigger drill.

Lubrication is necessary for an easier cut.

Know and understand what a sharp bit looks like and how to sharpen it.

Listen to the drill and as it starts to poke thru, hold back on the pressure and feed, not plunge, it thru.

RPM of the bigger drill bit (1/2") , assuming it is of good material, should not exceed about 600 RPM under lubrication.

Create a stance that allows pressure behind the drill, and the ability to hold it square thru the entire drilling process.
A wobbly grip in the drill asks for trouble.

I had a project a few years back where I had to drill 280 holes 1/2" diameter thru 5/8" steel. Broke one 1/2" bit and only
two 1/8" bits during the entire project. Sharpened the 1/2" bit several times thru the project.

Good luck !

 

[guido]

Hello bc,

This is what I would use. Drilling by hand at that size, you need a strong drill with a
handle. A work out, but can be done The drill press will make it much easier going.
Don't forget the lube of your choice!

Guido.

 

[Robert (ID)]

I've stretched truck frames, shortened truck frames, repaired and reinforced truck frames... those tapered reamers that guido showed are well worth the $$$ if you have very many holes to punch.. we bought a jancey mag drill and ran them with it.. it took the drill time on our standard stretch job from 2.5 days down to 1.

Also I don't know about anyone else, but there are days I can sharpen drill bits first try then other days after 3 tries i walk away... some days it just not productive to try and sharpen em. put em down get another bit and try to sharpen it another day..

 

[JayinNY]

I dont like drilling holes in steel either, if i have to
occasionally, i drill a hole with my drill and a bit,
then open up the hole with this, i have different size
cutting tips for it too. Good luck.

 

[super99]

You said that lubricating oil doesn't work, why?? I don't usually do a lot of drilling, but I've done quite a few and always just used motor oil on the bits. Chris

 

[MarkB_MI]

You want cobalt drills. And if your hole tolerance needs to be tight, drill undersize and finish with a reamer.

You can find drill speed charts that will give the proper RPMs for a given size drill in a given material.

Start with a pilot hole, say 1/8" and go up from there.

If your speed and pressure are right, you should get two continuous chips, assuming the drill is sharp. If you're not making big chips, you need to increase pressure or slow the drill down.

 

[Butch(OH)]

Over the years I have poked a lot of
holes in the machine shop, farm shop and
out laying in the mud under a machine.
My experiences are this, Cheap-good drill
bits are fallacy. So are the Super duper
drill forever bits. No, repete no, drill
bit will have a long life when used in a
hand held drill as compared to one used
in a press. Ultra slow spindle speeds
don't won't add a single hole to drill
bit life. Ultra slow feeding a bit
decreases bit life. Cutting oil will not
fix problems caused by dull bits or bad
operators. All that being said it is
possible to do what you need without
going through 100 bits and a months time.

Champion, also sold as Norseman sells a
pretty darn good bit. If your not going
to take the time to learn how to sharpen
them plan on a new one every 20 holes if
run correctly or as few as 1 if your
intent on destroying bits.

Speed charts are on the internet, plug in
a search to get started but I don't use
them. The chips tell the story because
the chip, NOT cutting fluids carry the
heat away from the bit. Silver chips
indicate you are well under max speed.
straw colored chips means you are right
on. Light blue chips means you are in the
danger zone and dark blue means you have
about 5 seconds to stop or the bit is
toast. If you have been drilling along
with good chip color and you begin to see
warning signs in the chip color that is
telling you that the edge is going away
on the bit. Choices are stop and touch up
the bit or continue on and destroy it.
There just isnt any way around it,
sharpen bits or buy a lot of them.

Do NOT step drill in small increments.
When I need 1/2" holes with hand held
equipment I use a 3/16" bit to pilot
with. Learn how to sharpen a bit, it
isn't rocket science or I could t do it.

 

[Bret4207]

When it comes to drilling heavier steels, 1/2" or above, a quality drill driven at law speed, with the right down pressure and a good lube is what it's all about. There are charts that give you the proper speed for a specific twist drill size and shape. Crap drill bits never give good results. Getting a drill press that will go slow enough is another problem. It's a balancing act.

 

[Dusty MI]

Two things.
Drill bits tips are flat, the pilot hole only needs to be as large as the flat tip of the large bite your going to use.
The "Drill Doctor" is a nice tool to sharpen drill bits with. There may have been a problem with a few of them.

Dusty

 

[bc]

Thanks. Beginning to figure this out. Was drilling some 1/4" holes the other day in 1/8" mild flat bar (for my pickup bed trailer tail gate) and the new titanium HF bits that I just got with a coupon using a 20v drill and it didn't really want to penetrate. Found my Ridgid cobalt bits and it would peel off metal like a curly que french fry.

I think some of my problems are that I am sometimes drilling on hardened steel where the bit makes a dimple to the half inch size and then quits with or without oil. I've also run into possibly chinese steel that just wants to flake out till the bit quits cutting.

Am going to make a 3 point hitch to put on the bale mover on the back of my pickup for a blade and maybe one to bolt on the front bolted in where the tow hooks are. Probably have a mix of mild and hardened steel some of which I can get on the drill press. I have some used grader blade cutter bars that I want to use.

Will try to pick up a reamer and maybe a tungsten carbide hole saw bits unless I torch the bigger holes.

I do have some 1/4" end mills that I may try. I've tried the pilot holes but sometimes in hardened steel those bits don't cut very good.

Guess it is time to practice some bit sharpening. Sometimes I get it and sometimes not. Haven't had much luck with the drill doctor on big bits. By hand on the grinder it is hard to get the angles just right and still end up with the center point the right width. Maybe my technique is wrong but I would grind the edge on one side and then twist my wrist to follow the taper going back. Then do the other side. If I don't taper on back then the cutting edge ends up low and doesn't cut. Seems like the drill doctor just does the edges and that's it.

 

[John Garner]

According to a factory engineer I talked to ten years or so ago, Viking and Norseman drills are identical except for their markings and marketing; Viking is primarily sold into the world of production manufacturing, Norseman into the world of Maintenance, Repair, and Overhaul (MRO). Their corporate headquarters and factory is in St. Paul, Minnesota.

Champion's corporate headquarters is in New York, and while it's certainly possible that Viking / Norseman is the OEM for Champion-branded twist drills, Champion and Viking / Norseman are not the same company.

 

[dr sportster]

A contractor would send you a magnetic base Hougen drill suited for many holes with special bits . Personally I have started burning a lot of holes with my Oxy/acet. Keep 'em round

 

[John Garner]

In the world of machining, a deep hole is several times its diameter. Over the years, I've heard "several" defined anywhere from three to ten times the diameter. The holes you want to drill aren't deep in machining terms.

Any good-quality twist drill should do what you want, but as others have said, cheap and good don't define the same drills. There are still a number of makers of high-quality twist drills in the US, including Ohio Drill, Norseman / Viking, Triumph, and Rocky Mountain, and high-quality twist drills from foreign makers include YG, Sandvik, OSG, and Guhring. These particular brands are ones that come to mind at the moment, there are others.

That said, there's a fair chance that a "Christmas tree" step drill would work well for you. Several years ago, a co-worker who was building his own airplane was bragging about his Harbor Freight set of Christmas tree drills, and I scoffed. A few days later, he gave me a set while saying that if I tried them, I'd quit scoffing.

I tried 'em, and I quit scoffing.

The ones he gave me are branded Drill Master, but it looks like today's version is branded Warrior.
Untitled URL Link

 

[mark1955]

if you can find any, Lawson drill bits, are very good, nasa uses them a lot. look them up. I can drill 10 holes, to one hole, of other brand.

 

[MJMJ]

You can always count on this place to make things way more complicated than they are.

 

[John Garner]

Care to tell us how simple things are?

Serious question.

 

[guido]

Hello bc,

Take two nuts, 1/2 or 5/8 inches, and tack them together on one facet facing each other. In between the
two nuts is your drill angle guide. I can take and post a picture in the A.M.?

Guido.

 

[rustred]

and that is how u screw up a drill bit is by going in small increments.! you drill your pilot according to the size of the point on the main bit. very important to use a drill press other wise your just screwing up a larger bit in a hand held drill.

 

[MJMJ]

(quoted from post at 19:10:53 11/04/20) Care to tell us how simple things are?

Serious question.

Sharp drill bit, a little cutting fluid of your choice, and a drill speed chart is available with a quick Google search. Try to keep the drill reasonably close to the ideal speed and that's really all there is to it.

Have you not read all of the replies here? It was a pretty simply question, drilling holes through steel isn't a real big deal. He could probably drill the holes faster than it takes to read all the advice here.

 

[the tractor vet]

I will second the Ohio Twist drills . I have them and have nothing but good to say about them . Then there is the fact that They are about 8 miles from my back door . When i need something i just take a ride out to Homeworth and get what i needed . They use to sharpen your drills for free , but like i said USE TO . And i have a CHEAP set in the basement that i use for wood , those you never want them to touch steel . One of my customers keeps buying them FINE bits from Harbor freight buy the index full and those your lucky if ya can get two holes drilled in mild steel . Then he saw how my Ohio Twist drills worked and went and bought the whole fractional , numbers , and letter set . Only complained about the price once .

 

[CenTex Farmall]

Forget any drill bit made in China. I haven't seen any yet that will hold an edge for very long.

At work we are using stainless steel 80% of the time. Good quality no frills drill bits will make dozens of holes before needing
to be sharpened (on a machine and with cutting oil or coolant).

Just find some American or European made bits and use something to help keep the heat down. Even used motor oil will be fine in
mild steel and you don't need to flood it and make a mess. One drop while you start the hole and then a few during drilling.

I also agree not to drill in small steps. I would use an 1/8 drill for a pilot hole for the 3/8 or 1/2. Technically you don't
need one that big for a 3/8 but for hand drilling anything smaller is easy to snap off if things get a little off. If the drill
is sharpened right you don't really need a pilot hole at all for 3/8.

I haven't been completely impressed by the results from the little sharpener machines. A guy at work had one and sharpened a
bunch of bits and they all needed to be hand finished as the machine left no relief right behing the cutting edge. They would
barely feed at all into the work. Keep practicing with the hand sharpening and you'll get there. A simple drill point gauge is
real handy. You could even cut one out of card stock. On mild steel the exact angle isn't critical, just try to make each side
the same; same angle and same length. Don't forget to thin the webbing as the final step.

 

[John Garner]

Thanks for your response.

I do agree with what you've said.
(Although I'd stay well under the look-up
table's recommended drill speed if using
a hand-held drill motor.), but I don't
see any drawback to explaining why
recommendations are made . . . especially
when the question-asker is obviously
exploring unfamiliar ground.

 

[guido]

Hello Robert ID,

Real world experience, may be you will get more attention if you highlight or print in bolt letters.

I used those reamer drills on aluminum framed tankers. Suspension bracket holes did not forgive a sloppy fit. Those reamers did the trick everytime!

Guido.

 

[Hockeygoon]

I agree - any oil is better than no oil. I usually have a bean can fill of used motor oil and keep dipping the drill bit in while drilling. I had it out with my son who didn't want to bother while drilling holes in the frame of his trailer to bolt the floor down. After he went through every 3/8 bit I owned and dulled them all with only a half dozen holes to show for it I sharpened them and showed him how he should do it (after I told him before he started). He was getting 6-8 holes between sharpening where as doing it "dry" would only get one hole - at the most.

 

[Ozlander]

If you're drilling by hand, make double sure the drill is turning the right direction.