# Drilling holes in 1/4" steel



## Backwater (Dec 14, 2014)

Ok, so I have this re-do galvanize trailer project going on and getting anal with it (will prolly do a thread on it), I'm running into a few snags with my customization of the trailer, which includes drilling 20 - 1/2" holes into the 1/4" steel. of the trailer frame and the 1/4" angle bar mounted on the heavy duty finder brackets. I'm trying to avoid buying a 1/2" drill again (last one grew legs and walked out on me). So I/m working with a 3/8" electric drill. I have some drill bits to go up to that size, but I don't think they are anything special and not even sure they are titanium drill bits. So I'm doubting they will last thru more than a few holes. Also trying to avoid loading the trailer frame up with fender brackets and taking it to a welding shop and having them zipped up. So, I bought 10 - 1/2" galvanized bolts (w/washers and nuts) to bolt them up.

So then, for you die hard steel workers out there, what is the best way to drill those holes? I figured I'd do a pilot hole with a smaller bit, then go with some "mac daddy on steroids" 1/2 inch drill bit. But I also saw those cone shaped bore bits (some with steps and some without) and was wondering if that is the better way to go. Don't know much about them.

Thoughts or experience with it? Remember, 20 - 1/2" holes drilled in 1/4" galv steel frame.

Ted


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## Smackdaddy53 (Dec 31, 2012)

Borrow a 1/2" cordless drill and buy a couple of good High Speed 1/2" drill bits and start out with a 1/4" then follow up with a 3/8" then finish with the 1/2". I would drill all 1/4" first, change bits and drill all holes out to 3/8" then finish with the 1/2".
The step bit you are referring to cost about $40-50 and are not for thick metal, more for drilling out electrical junction boxes and other thin metals.


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## mangoman (Dec 1, 2011)

Backwater said:


> Ok, so I have this re-do galvanize trailer project going on and getting anal with it (will prolly do a thread on it), I'm running into a few snags with my customization of the trailer, which includes drilling 20 - 1/2" holes into the 1/4" steel. of the trailer frame and the 1/4" angle bar mounted on the heavy duty finder brackets. I'm trying to avoid buying a 1/2" drill again (last one grew legs and walked out on me). So I/m working with a 3/8" electric drill. I have some drill bits to go up to that size, but I don't think they are anything special and not even sure they are titanium drill bits. So I'm doubting they will last thru more than a few holes. Also trying to avoid loading the trailer frame up with fender brackets and taking it to a welding shop and having them zipped up. So, I bought 10 - 1/2" galvanized bolts (w/washers and nuts) to bolt them up.
> 
> So then, for you die hard steel workers out there, what is the best way to drill those holes? I figured I'd do a pilot hole with a smaller bit, then go with some "mac daddy on steroids" 1/2 inch drill bit. But I also saw those cone shaped bore bits (some with steps and some without) and was wondering if that is the better way to go. Don't know much about them.
> 
> ...


Forget the cone shaped bit(unibit). First buy the highest quality bits you can find and start with a 1/8 pilot hole and step up to 5/16 and then 1/2. Also with steel slow constant rpms and pressure and plenty of oil when drilling. And hold onto that drill!


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## bryson (Jun 22, 2015)

What are you drilling half inch holes for? A half inch bolt is incredibly strong. I'm not sure of the application, but you might be able to get by with 3/8 or smaller.

Still, a single good quality drill bit should be fine for what you're doing. Keep the drill speed low, and use some cutting fluid if you'd like. You can do a pilot hole first to help stop the larger drill bit from walking on you.

One good thing about the stepped bits is that they do a great job of deburring holes. I'll often use a cheap stepped bit to put a slight chamfer on the edge of a drilled hole as well.


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## bryson (Jun 22, 2015)

Smackdaddy53 said:


> Borrow a 1/2" cordless drill and buy a couple of good High Speed 1/2" drill bits and start out with a 1/4" then follow up with a 3/8" then finish with the 1/2". I would drill all 1/4" first, change bits and drill all holes out to 3/8" then finish with the 1/2".
> The step bit you are referring to cost about $40-50 and are not for thick metal, more for drilling out electrical junction boxes and other thin metals.



I would definitely go with a corded drill. A decent 3/8" corded drill should have all the power you need for what you're doing. I'd also try to find one with a handle.


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## Backwater (Dec 14, 2014)

Smackdaddy, I found a pair of stepped cone bits (different sizes) in Harbor Freight for $20. That is why I was thinking about it.

Yea I figured I'd have to break out the oil, but I forgot about turning down the speed. Thanks for that guys! 

If I go with the regular bits, what is a good bit I should use that will last thru all 20 holes?

bryson, I got anal with the bolt bit size and already bought the bolts.


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## anytide (Jul 30, 2009)

good bits / start off small
slow speed / spray with WD40 using a trigger bottle to keep them cool.
they will cut right thru it.
one quality 1/2" bit kept cool /lubed will finish it.


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## Smackdaddy53 (Dec 31, 2012)

For 1/4" steel you can just use some regular bits from the hardware store, no need to really get crazy and buy high dollar bits when you can buy 2-3 regular bits for what one titanium coated bit cost. For 3/8 or 1/2" I would have recommended higher quality bits but 1/4" is not that bad. 
I mentioned the cordless drill because most of them have the low speed setting so you don't have to worry about burning up your drill bits or using lubricant like you would if you ran a corded drill at full speed. Once you blue the drill bit it is useless.


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## Smackdaddy53 (Dec 31, 2012)

Step bits are not meant for thick metal and don't cut like a regular drill bit, I'd stick with the regular bits.


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## Backwater (Dec 14, 2014)

Ok. I got a Porta Cable cordless with a 2 speed setting. I'll try that.


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## mangoman (Dec 1, 2011)

Backwater said:


> Smackdaddy, I found a pair of stepped cone bits (different sizes) in Harbor Freight for $20. That is why I was thinking about it.
> 
> Yea I figured I'd have to break out the oil, but I forgot about turning down the speed. Thanks for that guys!
> 
> ...


BTW 1/2 bolt will require a 9/16 hole and you could spray cold galvanize for some protection


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## anytide (Jul 30, 2009)

mangoman said:


> BTW 1/2 bolt will require a 9/16 hole and you could spray cold galvanize for some protection


good point!


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## Backwater (Dec 14, 2014)

Last question... Went by both HD and Lowes and both tool guys mentioned cobalt (the element) coated drill bits, not the brand Kobalt. They said they were the hardest coating, harder than titanium coated bits. Horribly expensive for a 1/2"{ and $20 for a 9/16. Do you think it would be worth it or just go with several cheaper bits?

BTW, good point about drilling bigger to a 9/16 (yicks, even harder.... )


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## Daz (Jul 14, 2015)

Go slow and keep it cool (wet). I've got a great big old 1/2" drill that'd be perfect for this - I'm down in the Englewood/Placida area - Let me know if you're ever heading down this way and want to borrow it.


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## MooreMiller (Sep 10, 2016)

150 grain round out of a .308 should punch about a 1/2" hole in that steel. Just make sure you are wearing your safety squints.


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## MariettaMike (Jun 14, 2012)

If you had a cutting torch, welding machine, and some cold galvanize paint you would be finished already.

(return the bolts before you lose the receipt)


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## Backwater (Dec 14, 2014)

MooreMiller said:


> 150 grain round out of a .308 should punch about a 1/2" hole in that steel. Just make sure you are wearing your safety squints.


That's what I shot my first really big buck with, up in Alabama when I was about your age!


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## Backwater (Dec 14, 2014)

MariettaMike said:


> If you had a cutting torch, welding machine, and some cold galvanize paint you would be finished already.
> 
> (return the bolts before you lose the receipt)


My small portable mig welder grew legs and walked out of my shop about 10yrs ago and I never replaced it.


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## anytide (Jul 30, 2009)

any bit is harder than the steel your drilling, move up in size/ drill slow/ lubricate.


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## WhiteDog70810 (May 6, 2008)

I burned up a lot of bits drilling metal before I learned to slow down. It can be tough to keep most variable speed (none of mine are adjustable) drills at ~150-200 rpm for the entire hole, especially when you have 20 holes to drill. Variable speed drills are also hard to hold and control when the bit grabs the bur when you first start drilling the bigger bit into the pilot hole. Consider renting a big, slow drill with a rear d-handle for a half day. It is easier on your wrists. Use lots of cutting oil.

Nate


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## Backwater (Dec 14, 2014)

I remember having to drill some T1 steel on a piece of heavy equipment I owned. Definately a big drill and lots of spray oil to keep it all cool.

Update - Did 10 holes today. Out of everything, the 1st small hole was the toughest, out of all bits I stepped up using. Tried real small, like around 3/32... nothing! 1/8" and barely made a dent. Finally found a 9/64" I had that was sharp and slow drilled it with a 3/8" corded drill that had a trigger than I can control the speed. Took a while to figure out the sweet spot (speed) and then it started cutting dood. Still, the smallest bit tool 4 times longer to drill than any other bit.

Once the smallest hole was established, I stepped up each bit 4 more bits till I reached 1/2". I did find that the lowest stress on the bits and drill and fastest drilling was stepping up 1/16" each step (bit size). Very slow drilling, no oil or water and the bits stayed cool. However, I guess I was too impatient to step 1/16" at a time. Maybe for the next 10 holes! 

I still need to go slightly bigger than 1/2 to fit the bolts. So I'm going to pick up the next bit up from 1/2" and a de-burring bit (which I have, up too a 1/2", but not bigger).

Definitely "C" clamping the angle bar on the fender (the thing I'm attaching to the trailer frame), to the Channel bar of the frame, since my holes didn't quite line up on the 1st fender.

Ted


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## Whiskey Angler (Mar 20, 2015)

Have not seen it mentioned, but Gulf Wax is an excellent lubricant for drilling. It what we use when drilling structural steel with our mag-drills (annular cutting bits) in the field.


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## State fish rob (Jan 25, 2017)

Go slow , lubricate


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## topnative2 (Feb 22, 2009)

cobalt bit........


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