Tips for drilling through metal?

I recently installed some cameras on an industrial metal building and had one hell of a time drilling holes into the steel structure for the mounting screws.

I assume the area I was trying to penetrate was 1/8". I was using brand new titanium bits but I ended up having to mount the brackets to some nearby sheet metal instead.

I'm not sure what I was doing wrong so I am hoping someone with more experience in drilling metal can give me a few tips. Drill bit type, drill type, etc.

 

I use to use titanium bits for dripping but found they tend to be a 1 hole then toss or sharpen.
I switched a couple years ago to these cobalt bits which worked a lot better, held an edge longer, and was able to still sharpen them on the bench grinder.

If doing larger holes, a uni-bit worked for not so clean but fast holes, or proper metal hole saw bits for cleaner holes (not the bi-metallic crap). I will try to find some links to post.

 

Here are the bits I've been using, mostly for camera installation incidentally.
We installed 32 or 33 cameras in an all steel industrial building. Bought this kit before starting the job and only killed 1 bit (broke it as I was leaning a bit on the bit, my fault).
I'm sure there are similar or the same kit south of the boarder. Since using these, I'll never buy titanium bits ever again.
https://www.canadiantire.ca/en/pdp/m...0658p.html#srp

 

So lets do some simple math.

The kit in the link has 100 pieces for $109 so that's about $1.01 each.

I just looked up the cost of the "jobber" bits we use in the shop for drilling steel.

For a 1/4" dia bit they run from $2.50 to $7.93 each.

I think we can say those bits might work ok for wood, but not for metal!

If drilling metal you need GOOD bits because the throw away wood bits will cost more in the long run!

 

Its more the frustration than cost for me. If I'm killing myself and my drill because the bits are as sharp as a politician, I'm having a bad day/job.

On a side note with the bits I linked, I bought them on sale. Canadian tire tends to over price stuff like bits, then through them on sale for much lower. $109 regular price, I paid $39.99 on sale and I'm guessing money was made.

I used those bits for just over 2 years (same kit) before changing careers (again).
I'm still using these bits for the large home renos, but is not as frequent as when I was a trades guy.

 

"Titanium" bits sounds like Harbor Freight Tools. It has been my experience (and a whole lot of other people agree) that any HF cutting tool is at best good for one use and often not even good for that.

I agree that cobalt drill bits are probably the best for drilling hard material.

 

Thanks for all the suggestions guys. Looks like cobalt bits get the unanimous vote here! I believe I got the titanium ones off of amazon but the quality is probably on par with HF.

I seriously don't care if the bits only last me to the end of each job as long as they don't have me feeling like I am the one doing all the work.

I always find myself saying get the right tool for the job and I guess in this case it means more than just a good drill.

 

Make sure the drill bit has sharp cutting edges and is for use on steel, rotating at reasonable speed ( drill has time to cut a continuous chip) and use lots of cutting oil (reduces friction). Applying cutting oil while drilling may require a helper.

 

I got the lecture years ago from a good friend that worked in our company machine shop, you need the right drill for the material you are drilling.

I didn't hear any comments about the angle of the drill point or the benefits of a pilot hole. I searched for a related link and this one looked good, better than anything I could write up.
https://www.regalcuttingtools.com/le...uld-i-be-using

I have probably 40 1/8th inch drill bits as they are my pilot drills. The tip of larger drills is flatish and it makes it hard to start a hole. Drilling a pilot provides a start and gets the cutting edge working with less pressure. Larger pilot holes are needed for larger drill bits.

For wood just about any drill will do, but for steel you want a drill bit intended for that purpose.

Bud

 

We often service pylon signs at commercial buildings and many cases the existing screws break off as they are so corroded. To reattach the signs we use Tek 5 screws. These will plow through 1/4" steel like butter.

 

Thanks for the new replies. Very helpful tips.

Tolyn, I think I will pick up some of those Tek 5 screws. Even If I cant use them for all applications it sounds like they will come in handy!

 

Like the others have said, cobalt is the way to go. I bought a few Bosch cobalt bits and am still on the first one. To give you an idea of their durability I drilled lengthwise through some Grade 5 bolts and that first bit is still going. As far as lubrication of bits at odd angles, try cut ease stick lubricant. Although it thins out once things warm up, it stays in place much better than any liquid oil.

 

Thanks, Rick, looks like amazon carries that cut ease stick lubricant.

 

Tolyn, do you happen to know what brand or what the Tek 5 screws you get are made out of? I'm seeing ones on amazon but they state they are for sheet metal and are made out of various metals.

 

These days almost any drill made in the USA is a premium quality and does quite well. Most drill sets I've tried from HF are junk and in the large set they aren't even different sizes. So, #28, 29 and 30 can all be the same size. I've had good luck with these bits but they are not the cheapest.

 

Most important things
-cutting oil
- slow drill speed
-slow feed rate

One trick for drilling a vertical hole-
To keep the cutting oil from just running down the wall, place a bar magnet just below where you are drilling to create a "shelf" to retain the oil. For round stock, flexible refrigerator magnets work.

 

Question - has anybody here tried case hardening their drill bits?
Either old dull ones or cheap HF drill bits?

My dad worked at US Gage and knew his way around the machine shop,
IRC, the process was:

1) Heat to red-hot and quench in old motor oil,

2) Reheat to just below red hot and quench in old antifreeze.

3) Polish the surface. Check the polishing by dropping the bits into a glass of beer and look for bubbles nucleating at rough areas; repeat as necessary. Supposedly, draft-nitrogenated beer is better for this than canned-carbonated beer. (apparently, you could get away with quite a bit if you were a mechanical engineer circa 1965...)

4) Rust proof by dipping the drill bits into old battery acid to clean them, when the bits are done fizzing pour a layer of old motor oil on top of the acid. Lift the drill bits through the oil layer slowly so the oil coats the metal before it gets exposed to the air.

 

Case hardening a drill? Just buy a good drill bit unless you are looking for a project. For me it's usually not even worth the time to re-sharpen the smaller ones let alone getting into case hardening.

 

I agree and not. For normal use, even light trade use, yes. When I was an installer, my drill was always used as where my bits. I use to spend more money per year on bits and a new drill per year than anything else in my tools.

 

Can one use oils other than "cutting oil" to lubricate and cool drilling? I ask because I'm going to be drilling a 1-3/8" hole in an older stainless steel sink to install a sprayer and I want to make the operation as simple as possible. AFAIK, the SS is quite thin -- probably even less than 1/16".

I've just bought a step-drill similiar to the one in the following video to do the job.
https://www.youtube.com/watch?v=ORXqvOevRbA

This is hopefully a one-time operation. I have various oils already on a shelf -- compressor, motor, WD40, brake fluid, etc., but no specific "cutting oil". Can I use any of these as cutting oil?

Thanks.

 

You can use almost any kind of oil. WD-40 could be used in a pinch but it's quite flammable so I would go for some motor or compressor oil.

For drilling a hole that large in stainless a step drill would be a good option. First drill a pilot hole about 1/8" with a regular twist drill. Then use the step drill to enlarge the hole. As you move up in size turn the drill slower and slower.

 

Thanks.

What do you suggest should be the approximate rpm for the largest steps? Is there any such thing as too slow?

Thanks.

 

I just found this hole-size versus rpm chart:
https://www.imperialsupplies.com/pdf...eet_Update.pdf

 

You could also use a metal hole saw.

If using this back the area with a 2X4 so it does not burr too much once you get through,
Also go slowly. If you overheat the stainless you will discolor it and look like crap.

 

Be sure to keep the step drill bit vertical or the hole will become out of round. If hole diameter is important, a manual hole punch ( like those made by Greenlee) is the way to go.

 

Unless you are skilled at eyeballing rpm, asking "what rpm" is sort of useless. For stainless steel a 18-20v cordless drill at about 80% of high speed is the max for your 1/8" pilot drill. By the time you get up to your largest size you should see one revolution at about the same speed you can count out loud; one, two, three. With stainless you turn the drill slower than usual and apply more pressure. When doing it right you should see continuous strips of metal coming off the drill. If it "chatters" or "squeals" stop, add oil and turn the drill bit slower and push harder. You can not have too much oil.

 

I wouldn't recommend transmission, brake, or power steering fluid simply because, I don't think they would take the heat as well, but motor oil works fine. With a drill press you can be more particular in regard to speed, but with a hand drill, as Pilot Dane mentioned, the feel and/or the sound will let you know that you're running too fast or too dry.

 

Thanks for all the great advice, guys! I really appreciate it.

 

Anybody know with certainty that the sprayer hole has to be 1-3/8, or can it be smaller and, if so, how small can it be?

(The tapset is being shipped to us as I type, so I can't answer this question for myself.)

Thanks.

 

If drilling with a step drill just take a break after each step and try the sprayer to see if it fits.... or measure.

 

The job is done.

I located the center of the sprayer hole and punched a good dent to keep the bit from wandering. I put a few drops of, believe it or don't, olive oil on the spot. I then used a new HSS 1/8" bit on very slow speed with a fair amount of pressure. At first I thought nothing was happening, but, sure enough, I soon began to see an accumulation of metal shavings. After a few more seconds, more shavings and soon puched through. I was amazed when I removed the bit from the drill. The bit was merely warm to the touch, not burning hot like I expected. The olive oil lubricated and cooled the bit fantastically well.

I then used a 1/4" bit, a few more drops of olive oil, very slow speed, more pressure, lots of nice shavings, and in just a few seconds punched through. This bit also was only warm to the touch.

Then more oil, the step drill, about 120 rpm, lots of pressure, amazingly nice shavings of SS, and in only about a minute of drilling I had enlarged the hole enough to allow the threaded shaft of the escutcheon to easily pass through the hole in the SS. Immediately after drilling, the rather massive step drill was not much warmer than room temperature.

I then enlarged and straighted out the cone-shaped hole in the particle board underneath the sink to exactly match the size of the hole in the SS all the way through the board. Then I installed the sprayer escutcheon and the new faucet (Moen commercial M-BITION model 8792).

I've learned that the key to easy drilling of SS (and probably other metals, too) is lots of olive oil, slow speed, lots of pressure on larger bits.

Good result, IMO.