Drilling 1/4" steal

I need to drill about 30 holes in some 1/4" steel. Finish size would be 1/2". What kind of drills bits would work the best. What sizes should I use up to 1/2" Thanks
 
I need to drill about 30 holes in some 1/4" steel. Finish size would be 1/2". What kind of drills bits would work the best. What sizes should I use up to 1/2" Thanks
Drilling is more of a feel then science, or set rules. There are some guide lines that you can Easly find depending of the type of metal you are drilling. One of the best way to drill many holes is with a reamer bit. Not only it will drill many holes, but the final result will be a consistent round hole size, very close to the bit size..

The reamer bit at 1/2 inch, will not drill the hole, but by looking at the tip you will know what size hole to drill the pilot. Speed KILLS! Lack of lubrication is a close second. Pressure and speed that produces good results is the key. 100 R.P.M.'S or a 1000 R.P. M.'S.

AND! If the drill is turning, with the proper pression for the speed, even @ 10 R.P.M.'s, maybe very slow, but it will do the job,

Guido.
 
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I think the key to consistent holes is a solid setup and a smooth feed. Pilot around 1/4" , then finish with your 1/2". If you need it to be really round, drill to 31/64" and ream with the 1/2".
 
It depends. The other mechanic I work with is convinced he is wasting time if he doesn't drill the full size hole in one pass. I sometimes can drill a 1/8" pilot hole, swap bits and still get done before he is finished. And he is over there with a ratchet strap wrapped around the drill motor and trying to 'jack' the bit through the metal.

You didn't say what equipment you had. A drill press would be best. You could do it with a hand drill. If it was me, using a hand drill, I would drill a 1/8" pilot hole, then probably a 5/16 or 3/8 drill, and finish up with the 1/2" drill. Keep in mind two other things:

The 1/8 drill can run a lot faster and still do a good job. Slow down a bit for the 5/16 or 3/8 bit and even slower for the 1/2" drill.

The other thing is if the bit isn't pulling out chips, either the drill is dull or the metal is too hard. If you have to make 30 holes, you will probably have to sharpen your bits at some point.

If I was using a drill press, I might try to skip the intermediate size 5/16" or 3/8" bit and see if the 1/2" could do the job, following the 1/8" pilot hole.
 
A pilot drill should be large enough to clear the web of the larger bit. I would use a 3/16 with a 1/2" bit if drilling by hand or if a drill press struggled to drill the holes with no pilot. Too large a pilot hole or step drilling a hole can lead to catching with a larger bit, so 3/16" pilot then right to the 1/2". Hand drilling, I like to clamp a block of 2x4 or such behind where the hole is. It reduces the catch and twisting of the drill as it cuts out the last of the hole.

Good high-speed steel drill bits should be fine for regular run of the mill steel. A bit of cutting oil doesn't hurt.
 
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A magnetic drill/press would be nice for that job, and they aren't real expensive. I've borrowed one before to drill holes in a frame, I will buy one the next time I need to drill a bunch of holes. I wonder if a good brand uni bit or step bit would work good, like the 3/16-1/2 size, that covers the pilot and a couple in between? Either way I would have at least a couple backup good bits to get the job done.
 
I need to drill about 30 holes in some 1/4" steel. Finish size would be 1/2". What kind of drills bits would work the best. What sizes should I use up to 1/2" Thanks

I need to drill about 30 holes in some 1/4" steel. Finish size would be 1/2". What kind of drills bits would work the best. What sizes should I use up to 1/2" Thanks
I'll be different than everyone else on here and probably get flamed for it but here goes. I have several sets of drill bits but when I need larger holes( 1/2 or larger) I use a hole saw. I have several that have drill hundred of holes in much thicker steel than what you are doing. I like Milwaukee the best, They have a pilot bit built in and the holes are always round, not like what you get when the bit isn't perfectly sharp. Flame away!!
 
Nothing wrong with hole saws in the correct application. They won't hold the same size tolerances that a twist drill will hold, but they can be "good enough" in a lot of situations.
 
What have you got to work with? Can you use a drill press on this job? How accurate do the holes need to be in terms of location and diameter?

You want to use cobalt drills, and you need to turn them slowly enough and with enough pressure that you get continuous shavings as you drill. Otherwise they'll get dull quickly. Center punch before drilling. I like to start with a 1/8 inch pilot hole, then go to 1/2 inch. You need to slow way down for the 1/2 inch bit.

If you need the hole to be exactly 1/2 inch in diameter, drill it slightly undersize and finish the hole with a chucking reamer.

You can find drill speed charts online that will tell you the optimum rpm for a particular material and drill diameter.
 
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Lots of good points on here. I probably have at least 3- 5 gallon buckets of drill bits. 4 drill presses, a milling machine and 3 mag base drills and a Cole drill. I drill lots of holes. If I am drilling a truck frame or something of the sort, nothing will beat the tapered reamers as stated by Guido. Anything over, say one inch I agree with Super 99. Hole saws are king. I have them all the way up to 6 inches. I cut a lot of 4 in holes in truck beds to install B and W Hitches. Don't know what size plates you are dealing with, but if they are small enough I would stack them up and probably drill 6 or 8 of them at a time, to speed up the process. 1/4 in plate is easy to drill unless it is T-1 or AR.
 
A magnetic drill/press would be nice for that job, and they aren't real expensive. I've borrowed one before to drill holes in a frame, I will buy one the next time I need to drill a bunch of holes. I wonder if a good brand uni bit or step bit would work good, like the 3/16-1/2 size, that covers the pilot and a couple in between? Either way I would have at least a couple backup good bits to get the job done
Brand name mag drills start at around $800, and go up from there. Thats pretty expensive for most people.
 
Most drill presses you are likely to find in a home shop and most hand drills will run too fast. Too fast is way worse than too slow. You need a chip coming off the drill to show it is cutting. If no chip or small flakes it rubbing and dulling more than cutting. Enough pressure to get a nearly continuous chip and some oil, any kind is better than none, and as slow as 500 to 800 rpm, and a sharp drill.
 
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Cobalt 3/16 and half. Don’t need to overspeed it you can go slow. Buy 2 of each is usually what I do and toss them when done.

1/4 isn’t thick enough for my mag drill anyway the magnet won’t hold 3/8 is about where I feel safe with that and then you would be using a cutter bit and Just popping them quick.
 
I need to drill about 30 holes in some 1/4" steel. Finish size would be 1/2". What kind of drills bits would work the best. What sizes should I use up to 1/2" Thanks

Most drill presses you are likely to find in a home shop and most hand drills will run too fast. Too fast is way worse than too slow. You need a chip coming off the drill to show it is cutting. If no chip or small flakes it rubbing and dulling more than cutting. Enough pressure to get a nearly continuous chip and some oil, any kind is better than none, and as slow as 500 to 800 rpm, and a sharp drill.
Good points. A quality drill bit has not been mentioned. Very necessary. I also like bits that have a back ground relief that narrows the point (also called split pointing), for drills making pilot holes. Jim
 
I've had a difficult time educating some people that "high speed tool steel" tooling DOES NOT mean high RPM or surface speed. I've watched a guy go through nearly an entire envelope of Hanson/Ace bits trying to go through 316L with the drill at 2,500 RPM. All I have to do is mention feed rate, and the look of a deer in headlights appears.
 
I've had a difficult time educating some people that "high speed tool steel" tooling DOES NOT mean high RPM or surface speed. I've watched a guy go through nearly an entire envelope of Hanson/Ace bits trying to go through 316L with the drill at 2,500 RPM. All I have to do is mention feed rate, and the look of a deer in headlights appears.
316L would be stainless steel. For stainless it is even more important to drill slow enough and with enough pressure to get the cutting edge of the (sharp) drill below the work hardened surface where the last flute cut. Slow speed, sharp drill, good rate of feed, and maybe some cutting oil for stainless.
 
My method has been plenty of drilling oil, specially made for drilling holes.
Second, select a pilot drill that is just wider than the tip of the final drill for the first hole.
Next, slow speed on the rotation with the final drill.
Then lots of pressure on the handle......if you are making a curl of metal off the piece, you are doing it right.

If drill wants to lock up as it punches through the bottom of the material, take it down to that point and turn the work over and clip the tangs off from the bottom....much easier on everything.

But I'm not a machinist.....just a guy trying to hang in there on this thing they call "farming"........but, "tools make the job." I can't tell you how many sticky situations I have gotten into and having just the right tool (some modified for the occasion) has allowed me to finish.
 
If you can find a matco tools tool truck, he would be able to sell you a "hyperstep" 1/2" drill bit. Likely a very good investment. easier on your drill, easier on you and a nice hole.
 

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