Drilling Angle Iron Problem (2023 Update)

[Pavel314]

I ran into a mysterious drilling problem and am trying to find an explanation.

My wife got a greenhouse kit from Harbor Freight. Good kit but not too sturdy; the doors and some panels blew off in the first windstorm. One of the things I tried to do to strengthen it was to attach a 6-foot angle iron to the light aluminum door header, which had been torn by the storm.

I bought a 1/8 inch thick angle iron at Home Depot, 3/4 inch deep on each side. The first thing I had to do was to drill four 1/2 inch holes about evenly spaced over the bar so that the iron would fit over the four nuts protruding from the existing frame. This was done easily, not binding or overheating of the metal in the drilling process. I used my hand drill for this.

Next I drilled six 5/16 inch holes in the thin aluminum header; again no problem. I then marked the corresponding spots on the angle iron, for where the bolts would go through. These holes would be on the same face of the angle iron where the 1/2 inch holes were drilled earlier. The first hole, at the right end, was easy. The second one, at the left end, just wouldn't go through. No problem, I got another 5/16 drill bit, same type of titanium coated bit with pilot hole maker; that one wouldn't go either.

That evening, I went to Home Depot and got two 5/16 inch cobalt drill bits. This morning, I tried one in the hand drill and it wouldn't go through the iron. Just made a dimple in the iron and stopped cutting. I took the angle iron into the shop and put it on the drill press with the second cobalt drill bit. It wouldn't drill through either, just made a slight depression and started overheating, turning the metal red it the drilling area. I tried drilling all along the bar but got the same results everywhere I tried. So I gave up on that angle iron and will get another or try an aluminum bar or a 2x4.

The thing I don't understand is why this iron suddenly became too tough to drill. When I drilled the original five holes, there was no overheating which might have tempered or crystallized the bar, especially not the entire

6 foot length of it. The original five were spaced out over the entire length, so it wouldn't be a case of localized hardening of the steel. And since I tried four drill bits of two different types, I can't blame a dull bit. Any ideas on what just happened?

Paul

[Joe]

That's almost too easy...you bought your angle iron at Home depot. It's Chinese, it has hard inclusions in it from inferior metal ingots rolled into shape and work hardened, maybe from cold rolling, at the mill. Go to a decent industrial supply outlet and buy some American angle iron. Maybe some experts here can discourse on hot- and cold- rolling as it applies to steel products, but that's my opinion FWIW. Might be able to anneal it to a drillable condition if you have a rosebud tip for your oxy-acetylene torch. HTH

Joe

[Jeff]

Sounds right, get a propane torch or maybe just your gas store and heat the part you want to drill as hot as you can, dull red. Let it cool, should be much softer.

That's almost too easy...you bought your angle iron at Home depot. It's Chinese, it has hard inclusions in it from inferior metal ingots rolled into shape and work hardened, maybe from cold rolling, at the mill. Go to a decent industrial supply outlet and buy some American angle iron. Maybe some experts here can discourse on hot- and cold- rolling as it applies to steel products, but that's my opinion FWIW. Might be able to anneal it to a drillable condition if you have a rosebud tip for your oxy-acetylene torch. HTH

Joe

[The Streets]

Ahhhh -- there's no chance that you accidentally reversed your drill motor is there?

[Kuskokwim]

If you read the entire original post you will notice he used a hand drill AND a drill press with the same results.

[The Streets]

And the OP ruled out overheating which might have tempered or crystallized the bar, localized hardening and dull drill bits. So what's left?

"When you have eliminated the impossible, whatever remains, however improbable, must be the truth." Sherlock Holmes

[Ralph Mowery]

Reverse was my first thought , but noticed he did use two drills. Then I thought of a left hand drill bit.

[Mark Witczak]

A couple of things about drilling angle iron:

1. Drill SLOWLY and use cutting oil to keep the bit cool. Heat will dull your bit fast.
2. Start with a small hole. Say 1/8" then increase the diameter until you get to the desired 1/2".
3. Buy a drill sharpener, you will need it. The bits sold at big box stores are only good for general purpose use (ie. wood, plastic, aluminum, etc.) Titanium sure sounds hard, but I've found it only extends the life of a bit 50% at most. Cobalt would be much better.

4.

[SteveB]

Now, who in the world would be stupid enough to do that?

I mean, except me. And more than once, I might add.

Steve

[SteveB]

If you ever have used both of these tools, they both have a reverse on them.

Trust me.

Steve

[Pavel314]

Wish it were that simple. Having done that before, the first thing I checked was to make sure that the drill was in forward. It was.

I stopped at Lowe's this evening. They had steel stock in two flavors, hot rolled and cold rolled. I bought a hot rolled angle iron and will try it tomorrow. Just in case, I bought an aluminum angle iron. I mean, aluminum angle bar, I guess. If the hot rolled won't drill, I'll try the aluminum.

Will keep you all posted. Thanks for all the replies, I appreciate the help. The idea of heat treating the drill areas is good to know but for $15 I decided to try the hot rolled.

Paul

[samurai]

Try scratching the area with a nail or a file. If it scratches easily with some depth, it should be similar in hardness to 1018, which is really easy to drill. If your file just glances off, then you've got a much harder product, and will have a tough time drilling, like trying to take a file to a bearing race.

Also, if you've heated the metal 'red hot' with the drill bit, the drill bit will have to ground down past the blueing that has occurred on it, as the heat has transferred to the drill bit, and softened the cutting flutes of the drill bit. Use coolant, oil, water, anything to avoid getting the drill bit hot.

samurai

[Stormin Mormon]

Were any of the bits (that didn't drill) new out of the package? I wonder if you had four or five dull bits. As others have suggested, maybe your drill got reversed. Though, you'd think after half inch holes, that the angle iron is definitely drillable.

[hallerb]

start drilling by drilling small hole then upsizing to larger one once your thru.

angle is often made from scrap, so one spot might be butter soft and a couple inches away part of a old engine block super hard.

try different angles and buy good bits, the expensive ones. those gold colored ones are junk

[hallerb]

be sure to use cutting oil to cool the work and keep bit sharp. local harden spots are very common.

i have learned a lot from my best friend with a machine shop i have had problems drilling angle too:(

[123]

Lets see. You bought some junk from Harbor Freight. MISTAKE ONE Then bought cheap imported steel from Home Depot MISTAKE TWO I wont even ask what brand of drill bits you got at Home Depot.

By now, you could have bought a decent kit from a reputable company for likely less money by the time you add all the drill bits, iron, and trips to the store, not to mention the frustration and hassle.

Harbor Freight sells junk and only junk. If enough people stopped buying their shit, they would shut down and go back to China.

People like you who buy from H.F. or other junk companies like this DESERVE to be screwed.

Put your drill away, take the angle iron to a scrap dealer and return the original thing to Harbor Freight, and tell them where to shove it. If they refuse the return, file a small claims case.

You learned the hard way, now you suffer !!!!

[Kuskokwim]

Since the metal from different sources is melted down together in the same vat, don't you think it would mix together to form a uniform product? How could it possibly remain segregated?

[Joe]

If you ever worked in a foundry (I have) you'd know that the iron coming from the cupola is simply melted, not stirred. It stays melted for some time to achieve uniformity and a sample goes to the lab for testing before the pour. However in a continuous process like in a steel mill in a hurry, there can be insufficient time for that pocess to take place. In addition, the lab work takes time and we know that the Chinese mills and factories are prone to shortcuts that affect quality, so the QC tests are likely infrequent or absent. HTH

Joe .

[Robert Barr]

Just another utterly useless comment.

[beecrofter]

You hit a hard spot. Not uncommon. Try a carbide masonry drill.