Tip for drilling through hardened steel

[number1cas]

Here's a tip for drilling through hardened steel, and I mean the stuff that the best quality drill bits can't make a mark in.

I bought a worm drive wiper for my Avenger and opened it up, I found that the degree of swing was adjustable by inserting the linkage arm into holes that are spaced further and further from the center of the gear, however the degree maxed out at 120, so I decide to drill another one further out to try and get closer to 170 to clean both sides of the windshield. I attempted it with every bit I could get my hands on including a center drill from my lathe, barley made a mark in it. I took it to the machine shop here and he said he couldn't drill it, but a special carbide drill (not the ones made from carbide) but a 2 flute carbide headed one may work.

Well I went to the internet and started reading, somewhere I read that you could use a masonry bit, so off to Canadian Tire and $2.50 later, I tried the masonry bit in the drill press and........ whammo, cut through like a hot knife through butter !!! Amazing !! I am still amazed as this stuff was HARD ! Like I said, the best drills barely made a mark and burned out the bit right away.

So save some money and try your masonry bits when the going gets hard !

[Tom]

It does work ,just watch your speed/feed rates.I have not tried it on glass but I've heard it works on that also.

[Jeff t-boss]

In my 30+years as a mechanic, I have drilled some EXTREMELY hard steel as you described. The best way I have found was to first, use a very small bit (1/8th or less) and drill a pilot hole. Then step up two sizes at at time to the final bore you want. Doing all of this with slow speed and moderate pressure, and cutting oil on the bit. HSS bits worked fine, but I prefer cobalt bits. They work alot better on stainless. Just remember to keep the speed down, and the pressure slightly up. (Approx 30-45 rpm for stainless)

[number1cas]

Yeah, that's how I attempted it at first, but a 1/16th bit would only wander and put a shine on it. A friend of mine used to be the Worth rep and had a set of cobalt bits that he had used to drill stuff other guys couldn't so i tried those too, they made a tiny little mark, like I had center punched it. I could not punch it first or allow too much heat to build as the steel was attatched to a plastic drive gear and the plastic would crack or melt.
The masonry bit and some cutting oil was the ticket.

[Roger S]

Besides good bits, it helps to have one thats ground to cut all the way to the center of the drill's web, otherwise you're trying to push metal out of the way, under the tip of the bit.

[mark m.]

Besides good bits, it helps to have one thats ground to cut all the way to the center of the drill's web, otherwise you're trying to push metal out of the way, under the tip of the bit.

Roger, these are otherwise known as a split point.

[rdr]

carbide end mill works tooo . robbie