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I believe my question is "how do I drill a steel plate so I can screw something to it"

As per a few of my other posts, I'm trying to reduce the gap between my garage door and floor.

The garage door and floor are (now) level with each other, and so I had hoped to include a draft excluder to help keep out most of the water and cold air.

I bought this draught seal.

The problem is, I can't screw these screws into the metal garage door (nor did I expect to be able to). I then looked up how, and it shows use metal drill bits, around 2mm, to create guide or pilot holes.

I've done this, and am unable to pierce the metal. I have a MAKITA DHP485STE 18V 5.0AH CORDLESS COMBI DRILL which I believe is more than powerful enough

I'm beginning to think their term for garage door means wooden, where as I have metal.

Is there any special trick to drilling through metal because, I was able to drill through the metal sheet that holds the plastic draft excluder without issue (the one in the link above). It's just the garage door seems to be made of super strong metal!

EDIT

As per comments, I've added a picture and have a dreadful feeling I can see the issue... That I'm not just going through that front plate (which is about 3mm thick)... I hope you can see the 2 places where I've tried to drill myself. I can get 0.5 - 1mm deep and then the drill bit seems to do nothing else

enter image description here

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    What do you mean "unable"? Do you have decent quality drill bits that are still sharp? Nothing on a typical overhead door should be difficult to drill. Please post a clear photo of the area you're working on. – isherwood Nov 16 '20 at 18:56
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    @isherwood, thank you again (you seem to very active here, your comments and posts are very appreciated). I have added a picture – MyDaftQuestions Nov 16 '20 at 20:03
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    Thanks. That door is of more robust construction than most modern U.S. doors, but you should still be able to drill it fairly easily. Sharp, good quality bits are key. – isherwood Nov 16 '20 at 20:05
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    Wow, not your average metal garage door. Serious steel, but drill-able with a sharp bit and oil. I believe your question is "how do I drill steel plate ?" – Alaska Man Nov 16 '20 at 20:10
  • IMHO your bit is dull, try a fresh one. – Agent_L Nov 17 '20 at 11:20
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You need to use self-tapping sheet metal screws. You should be able to find these at any home center or hardware store. The metal garage door is a thin sheet of metal, usually aluminum or steel with a foam core and another thin sheet on the other side. If it's uninsulated, then there is usually only the outside sheet but there should be a "U" at the bottom that gives you a flange to attach to.

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    If the OP can't drill holes with an actual drill bit, how will this help? We need to understand the problem better. – isherwood Nov 16 '20 at 18:56
  • Yup! Any sort of wood screw, drywall screw, decking screw, etc will do nothing but get scoffed at by even the thin sheet metal of a garage door. – FreeMan Nov 16 '20 at 18:57
  • I'm fairly convinced the screws that the company supplied are bog standard wood screws - nothing clever about them :( – MyDaftQuestions Nov 16 '20 at 20:04
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    After seeing the door in question and noticing that it's of fairly heavy-gauge steel, I'd recommend self-drilling screws, which are a type of self-tapping screw with a bit integrated into the tip. Needle-point screws may not do well. – isherwood Nov 16 '20 at 20:04
  • Self drilling screws were the answer @isherwood – MyDaftQuestions Nov 21 '20 at 19:44
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Your drill should definitely handle a 2 mm drill bit. Make sure it's a drill made for metal. Use a nail and hammer to countersink the hole. Then follow with the drill. I have always used a drop or two of oil, (3 in One works great), when drilling as it will cool and lubricate the surface as well as prolonging the life of your drill bit.

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  • After this attempt it's probably worth buying a pack of several 2mm jobber drills, to be sure of having a sharp one. I suspect that trying too hard has blunted the drill the OP has. – Chris H Nov 17 '20 at 13:09
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I think you've probably got three things going on here:

  1. Dull bit to start with. You need a sharp bit to drill steel by hand.
  2. Inappropriate bit that dulls faster in steel. Often times, the drill bits that you'll buy in sets at the hardware store have a 118 degree angle on the tip rather than the 135 degree angle that is better for drilling in steel.
  3. RPM not high enough. It takes a higher RPM to drill a small hole than it takes to drill a large hole. "Power" isn't the problem, it is speed. Power only comes into it as far as it takes power to maintain the speed under load.

I find that battery powered drills don't really have the speed it takes to drill with small bits. I like the German name for battery powered drills better - "Akkuschrauber." That's "battery powered screwdriver" rather than "drill." A screwdriver doesn't spin any where near as fast as a drill.

The holes you started look like ones that I made when I tried using a battery powered drill to make holes in steel. I gave up, and went and got my regular drill. That worked just fine.

  1. Get a normal drill instead of the battery powered one.
  2. Get a new bit (or sharpen the one you have.)
  3. Use bits with a 135 degree point.

Feed rate enters into the problem as well.

"Feed rate" translates to "how hard you are pushing the drill into the metal" when drilling by hand.

Given where you need to put your holes, pushing hard is going to be difficult. You can't really "put your back into it" because the holes in an inconvenient position, and even if you could the metal will flex when you push hard. Along with that, drilling a 2mm hole and pushing hard on a hand drill is a good way to break bits - if you push just a little bit off of straight, you'll bend and break the bit.

Higher speed, sharp bit, proper bit, and a spot of oil are your best bet.

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    The correct speed is definitely a factor, but I'd have to disagree that going faster is the right way to do it. I've burned plenty of bits by going too fast and I've cut through steel easily enough with a "slow" speed on a drill press. The chart you gave shows a max RPM, not the target RPM, so that's a bit of a red herring. I've drilled through plenty of metals using a 600 RPM cordless and a 800 RPM corded drill. And having the correct and sharp bits are definitely critical here. You don't want to accidentally work harden the piece. – computercarguy Nov 17 '20 at 17:21
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An alternative to drilling could be to glue the seal to the door. I think epoxy would do the trick, giving a strong bond even in cold weather. For example, Araldite. If you go ahead with this, use the slower setting ("Standard", I think?) glue - the Rapid stuff would set before you could apply and position the work. You will need plenty of clamps to hold it in place whilst the glue sets. However - I only mention this to give you another option - I think screws would be far better, as the seal could then be removed in future for maintenance / replacement, which might well be impossible with a strong epoxy bond.

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All drills have an optimum speed and feed rate. The smaller the drill bit, the faster it should be spinning and vice versa.

Looking at your two previous attempts I would say either not enough pressure on the drill bit (you may have to put something big and heavy behind the door if it is flexing when you apply pressure to the drill) or a dull blunt drill bit. Either of these will cause both the drill bit and and door to heat up and you end up "polishing" a depression into the metal instead of actually drilling.

When a drill is at its optimum speed and feed rate, chips of metal will come off more or less continously. Especially with hand tools, the pressure required to get the correct feed rate is often much more than you'd think!

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