Drilling Iron

Consider a Roper-Whitney punch instead of drilling.

Hi Jamie,

You're drill in in steel, mild steel most likely. Typical angle iron is generally 1020 hot rolled. That is considered low carbon steel (this the term "mild") and is not heat treatable.

Regards lubrication, I'm not a fan of lard oil, never have been in all my

46 years in the shop. Don't like the smell or the feel. Don't like the smell of sulfur based cutting oil either, but I do use it. You can buy that at Home Depot I've been told, but I buy it in 5 gallon containers from oil distributors. Need I say they last a long time?

Drilling by hand is tiresome and not very accurate, but if that's what you're stuck with, try drilling your hole with a smaller drill and opening the hole to size. The chisel point of drills makes for tough drilling, so the smaller the drill the better. Small drills have a smaller chisel point, and you're also removing less material, so it goes a lot better. Don't go too small, though, because drills have a funny way of breaking off as you push on them. Small ones break very easily.

If your countersink dulled quickly, it's likely from running way too fast, with a remote possibility of running backwards. That's death on cutting tools. It's difficult to say what is fast and slow, all depends on the type of drill motor you're using. If it's a 1/4" capacity, it's likely to be very fast. Likewise, a gear reduction heavy 1/2" drill motor runs quite slow. It would be difficult to say how far to pull the trigger on your particular drill motor. You get the idea.

A good indicator is if the drill tip or counter sink gets real hot, hot enough to change surface color. That's definitely running too fast. Chips that come off should not be colored either, nothing beyond a light straw color at the most. If they come off blue, again, you're running way too fast.

If you have a lot of this work to do, you might entertain the idea of getting a small drill press. The difference in drilling steel with a press as compared to hand drilling is unbelievable.

Good luck with the project~

Harold

Thanks for the suggestion, but it looks like I'd need a model 7A, at least, and I can't find a price for one anywhere. If it's any more than a few sawbucks, though, I'd probably do better to put that money toward a drill press.

Jamie

Great info, Harold. Thanks. Also, I am indeed entertaining the idea of a drill press, but doubt the money will turn up before this project is over.

One more thing, will it be obvious what to do with the sulfur-based lubricant? Just put on a couple drops where I'm about to drill, and add more as it needed? Not sure if "a little dab'll do ya" or if I need to get it pretty flooded.

Thanks again, Jamie

If you must use a hand drill, use sharp bits..learn to sharpen them if you don't know, or buy a bunch, use lubricant...even soapy water in a spray bottle is a good lube-coolant. I would find somebody with a drill press and buy the beer, or the single-malt if you REALLY have a bunch to do. Slow on the countersink.

snipped-for-privacy@bigfoot.com (Jamie Jackson)

As previously stated, you're drilling mild steel. Yes use lube. (I like the soapy water suggestion) If you have a combination drill/countersink bit, that might help. I would suggest a machinist's center drill (combo short drill and 60 deg countersink). Wood screw screw heads are not at that angle, however. They may be close enough so you might try that anyway. FM

Common shop practice is to use a small can with a piece of (heavy) stock in it to prevent your air hose from blowing it around. In the can you want an inch or so of this oil, which is dark, like molasses. An acid brush is commonly used, which is held against the drill as it enters the work. That's enough lubrication for drill press (or drill motor) drilling. One dips as needed. You don't need to keep the thing wet, like flooding with a pump. The oil not only lubricates, but cools as well. You can get away with slightly higher speeds with lubrication.

Harold

Most hardware store steel is mild steel unless stated on the tag. You don't indicate how many holes you will be drilling but if they are a few hundred look for a drill press. Even one of the cheap asian imports from Harbor Freight would be a better solution than drilling by hand.

Buy good drill bits. Look for a contractors supply house and buy the size you need rather than a index full of bits.

Run the drill (hand or press) at low speed. For lube I use Isopropyl Alcohol (rubbing alcohol) in a squeeze bottle. It evaporates and leaves no residue which helps when prepping the steel for painting or welding.

(warning and disclaimer for the chicken littles - yes, this can catch fire and burn your house down - use with caution and in well ventilated areas or add water to the mix up to a 1 for 1 ratio - end warning and disclaimer)

Squirt on to the steel at the start of the bit and add more as the hole forms. If the mixtures boils off the steel your drill is moving too fast, too dull or your not keeping it wet with lube.

My 2 cents, good luck

Jim Vrzal Holiday,FL

Jamie Jacks> I've got a lot of drilling to do in iron (?). This is the kind of

I don't know how many or the size of the material, but Harbor Freight's cheapie benchtop drill press are usually around $50

In addition to the other possibilities mentioned, you may be countersinking with too little pressure. If the tool "skids" on the work without cutting, it can get dull pretty quickly. If you are not making chips, then take ALL pressure off the cutting tool.

If keeping cutting pressure on the tool makes blue chips or bogs the drill motor down, maybe you need a slower gear (1/2 inch drill motor instead of 3/8 or 3/8 instead of 1/4); some newer cordless drills have two-speed gearboxes, too.

-- --Pete "Peter W. Meek"

That sounds like a good idea, given my countersinks could stand to be more conical (which, it seems that bit would help with). In which category in the yellow pages would I find a retailer?

Thanks, Jamie

Excellent, I woudn't have known any of that.

Thanks again, Jamie

Greetings Jamie, As others have said, you are probably drilling mild steel. It should be drilled at, in your situation, about 1500 rpm for a 3/16 drill. As others have said, use cutting oil. You can get threading oil at the hardware store. The dark, smelly stuff will probably work best. For use with a hand drill you can just dip the drill bit in it and then start drilling. Re-dip as needed. Watch the chips and if they are turning color (blue, brown, etc,) slow down the rpm. For 1/8 thick material and 3/16 dia. holes a drill bit that should work really well is a "Bullet Drill". These used to be sold under the Black & Decker brand. These types of drill bits have a pilot ground on the tip which has a split point. Then the end of the major dia. of the bit looks flat. These bits have a split point on the pilot which takes much less pressure to get through the work. These bits are self centering. They leave a very small burr. Run your countersink half as fast as the drill bit. Cheers, Eric

Thanks, Eric. My hardware store does have the "threading" oil, so I'll pick that up. Apparently, drilling oil (Duracut 260 seems right --

is harder to find.

I do have some of those pilot-tip bits somewhere, so I'll try that on some holes, and see how it does.

Thanks, Jamie

You have gotten lots of good advice. I will add a couple more comments. Anything will help for lubricant. One of the things a lubricant does is keep things cool and obviously anything will help there. Oils also lower the friction, but require cleaning before painting.

Using a pilot hole will help a lot. The general rule is to use a drill that is the same diameter as the web of the next drill. And the next drill should be the size of the hole you want ( unless the drill motor you are using does not have enough power ). Sometimes I drill the pilot hole almost all the way thru and then fill that hole with oil before drilling the full sized hole if I am drilling thick material.

You may want to put a piece of scrap wood behind the metal so that the drill does not grab as much as it goes thru the far side.

I would also recommend you let people know where you are located. Someone here might be willing to let you use their drill press, have a drill press to sell, or recommend a good place to buy drills. Here in the Seattle area Boeing Surplus sells good drill bits at good prices.

Dan

I was waiting to see who mentioned this detail first. Go Harold

Blue chips are bad

that is, drilling low carbon steel with tool steel making blue chips is bad.

The original poster's description of the drill bit as "Titanium Nitride" is a little inaccurate. The Bit has a coating of TiN, but the bit itself is still high speed steel. The TiN helps with wear, but the tool is still limited by its base material. Besides, I seriously doubt consumer grade TiN coated bits are much better than commercial grade non-coated...

I sold this 20-ton model that does 1/2" holes in 1/2" thick steel for $132 on eBay recently:

If you consider eBay as a "tool lending agency", you could probably do all the holes you need, then sell it again and get your money back.

Richard J Kinch Palm Beach County, Florida USA

Thanks for the tips. You gave me two more questions, though. ;-)

IDAGS, but couldn't find out what the "web" of a drill bit is. Anatomy lesson please? Also, you mentioned cleanup after the oil and before painting: Mineral spirits?

And FWIW, I'm in Falls Church City, VA, and would consider a used drill press (better a nice-ish old press than a new cheapie).

Thanks, Jamie

Very true.

This isn't optimal on a small (17" or less) drill press because the forces involved will cause the table to flex. This will cause your hole to go out of square which isn't a big deal on thin stock, but it also can wear out your bit prematurely. If you don't believe me, put a dial indicator on your table and press down on it with normal drilling force and see it deflect. This is the reason for step drilling i.e. beyond web-sized-pilot drilling.

Good idea. It means the big drill breaks through though, so it makes clamping the part more important.

Second the "where are you". My first drill press was free. My second one cost me $35 and it did me well for several years.

One final comment: for any hole larger than 1/8", it is really easy to punch 1/8" steel. You'll want to centerpunch your hole and catch the centerpunch with the tit in the middle of the punch (this locates the hole quickly and reasonably accurately). Small arbor presses can be easily converted to light punches for low $$ and low shelf space. You'll find that it's a whole lot faster and easier to punch holes a tad oversize with a little tolerance for location, than it is to locate and drill holes precisely.

Grant Erwin Kirkland, Washington