Why can't I drill a 1/4" hole?

Something that I've not seen mentioned yet, and that needs to be considered....how well is the steel annealed? To explain, most steel is delivered in a "spherodized" annealed form. My term for this is "half annealed". Often times you can start drilling a hole just fine, but then you get about 1/3-1/2 way through, and hit very hard material.....in the case of 1/4" versus small bits, it will be much more evident that larger the bit you try to use.

Almost without exception, any time I produce a stock removal knife, it requires that I fully anneal the material before starting work.
 
Cobalt lasts much longer for just a little more money. Try pecking the hole, don't let the heat build up. Once again, don't let the smoke out of your cutters!
 
HSS drills will drill almost anything. When you get the harder stuff, cobalt will definitely help. Hardened steel will need carbide if you can't bring it back soft.

I run my drills at work constantly, I have some in my box that I have used for years. They need to be resharpened every now and then, but that is a skill that one needs to know. Much cheaper to sharpen drills than 'toss em and buy new. Eventually you will sharpen them back too far. The web size increases as you come down the length of the drill. You can always relieve the web, but it still is easier to push a thin web drill through. Pick yourself up a drill point guage and work on sharpening with a bench grinder. Not bragging by any means, but as a tool maker, I can get almost anything to cut. I have pieces of broken tools in my box that I have resharpened to make cut the way I want them to cut. You have to understand the geometry of the cutter/drill point to make it work in your favor. The most importnt thing to know about sharpening a drill is that it has to have the right relief and it has to be the same on both sides. If not, it will drag, and if not the same on both sides, one side will cut more than the other and the hole will be oversize. Tell-tale sign is only one chip spiraling up out of the hole instead of two..

I turn my 3/16 drills at about 1000rpm in almost any kind of tool steel...A2/D2/S7. Keep plenty of coolant on it, pull it out to clear the hole every now and then and use enough pressure that the drill cuts. Don't sit and spin like Boss says. As I work up through the sizes of drills and get bigger I slow down RPM. I would turn a 1/4 at about 650 or 700, a 5/16 at about 575, a 3/8 at about 500, and a 1/2 at about 400. Motor oil will work better than WD40 if you have some around. WD40 is too thin. The best thing to use is coolant though. It works great.
 
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I feel your pain. I'll bet you got hot rolled, unannealed steel. This happened to me and the 1080 steel I bought. I tried all sorts of things to soften it up. I find that if I put the steel on my glass topped kitchen stove on high for "a while", the steel surface turns very dark (if the slag was removed prior and the steel clean). I can drill holes in it using cutting fluid. I'd never used cutting fluid before but it does help.

I still can't cut it with a high tension hacksaw and normal blade, I need to use a carbide blade and it goes very slow.
 
One thing I recently found works well for hardened steel is, believe it or not, a carbide tipped masonry bit. I don't believe they are any more expensive than cobalt, but they actually work quite well. Now, I doubt they end up as accurate as a twist bit of the same size (I haven't checked this) but they sure do cut a lot better.
 
joe levy said:
Most masonry bits are over sized.

Joe
Click to expand...

Thanks for clarifying. I had a feeling that hey made a slightly wider hole than the "advertised" size.
That being said, if you can afford a little bit of wiggle room, it's a much easier option than burning up/breaking a bunch of HSS or Cobalt bits.
 
It's the steel. I ordered some 1080 and 1084 from Kelly when I first started making knives and had the same problem. After smoking dozens of bits, including a pile of cobalt bits, I ended up using carbide tipped concrete bits to get holes in it. Even then I could only get 6-10 holes before the bit would break. I switched over to stainless steel for my blades and left the carbon steel sitting in the corner of my shop. One of these days I will get around to annealing it and use it up.
 
i only use colbalt bits on metal . and use soapy water for a coolant,works great. the coolant is 2 table spoons of dawn dish soap or simple green in a quart spray bottle. soapy water works on your sharpining stones to.clean them right up. gary miller
 
Alright, finally a progress update. This time I was drilling some 3/16 D2 with 1/4" holes in the tang prior to tapering. Historically the D2 has killed my bits quick. This time I did several things different. I turned up the speed one notch. I pushed a little harder. I also drilled just a little, added a drop of motor oil, then drilled some more. The result was that I drilled 11 nice holes so far with no bit trouble.
 
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