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I have been working on some pick designs and prefer high-end hacksaw blades as material. It is already heat treated to perfect hardness and flexibility, (once you grind off the bi-metal teeth). Of course over-heating the blade while shaping on a bench grinder will destroy the temper, and you must dip in water frequently to avoid softening or burning the metal.

There is another problem with using already hardened steel as I found out after trying to drill pin holes to secure the handles. I chipped my center punch and believing the punch was at fault I went out and bought an expensive auto punch. Unfortunately the point chipped on it as well after the first mark. Then, while drilling the second hole with a standard hss no. 39 bit, the bit grabbed on break-through and heated the surrounding area burning the steel. Now it dawned on me that both the centre punch and the bit were designed for soft (annealed) steel and the hacksaw blades were too hard for the tools.

Solution:
1. I could anneal the steel by heating it cherry red and slowly cooling it in the hot ashes of a forge. The steel could then be worked and re-hardened and tempered. However, having no idea as to the type of steel, chances are it would be difficult to get the correct hardness/spring back. Many modern steels require super-cooling in liquid nitrogen etc. - way too much like work.

2. I could change the way I mark and drill the already hardened steel. Marking the drill points is not necessary if you use the correct drill. A cobalt or tungsten bit will drill hardened steel, but both are brittle. A standard hss bit will work, but the point angle needs to be 150 degrees. Some of the newer twist bits have a negative cutting edge that prevents the point from walking, so a centre punch is not necessary.

3. I can buy a bunch of regular hss bits and throw them out after a couple of holes. (It is way too hard to sharpen very small bits correctly.) Plus I can re-sharpen the centre punch after every hole.

For now, until I can track down the proper hss bits, I will change regular bits after each hole or two, and maybe try and re-sharpen them. Ditto with the punch. Once I find a source for 150 degree pre-ground bits with negative cutting edges I will go that route.

If anyone knows of a source for the 150 degree negative edge bits let me know. (I need numbered bits, specifically #39.) Meanwhile, if you are drilling hacksaw or other hardened steel, be careful or you may ruin a half-finished pick as I did.

you could try Straight-Flute Solid Carbide Drill Bit works for me.

http://www.mscdirect.com/browse/Holemaking/Drilling-Drill-Bits/Metalworking-Multipurpose-Drill-Bits?

Thanks for the suggestion. Do these bits cut hardened steel without dulling quickly and do you need to centre punch? I imagine the carbide does last. In checking your reference I see only 64th sizes, - I may need to find different size pin material as the ones I have require a #39 drill for a tight fit.

I use them to drill out broken off tap. at work no center punch needed if you go at a slow speed.

Another alternative to try is "spot annealing";
- Cut the head off a finishing nail then sand or grind the end you cut off flat.
- Put it into a drill press chuck with the pointed part of the nail up and inside the chuck.
- Holding the part you want to drill with a pair of pliers, turn the drill press on and bring the nail down onto the place you want to drill the hole.
- use the heat created by the friction of the nail spinning on your part to destroy the heat treat at that location.

Good suggestion. Actually I changed the size of my pins so a 3/32" works and was able to find cheap carbide bits, although I now start with a centre drill and then enlarge the hole to 3/32" so it is not that hard on the drill bit. I do have to sharpen the centre drill often, but they are relatively easy to sharpen by hand. I may try your idea to make it easier on the centre drill, which will, depending on the hacksaw alloy, soften it. Although the teeth are a tough alloy, I think the rest of the blade may be a carbon steel which heat will soften.

I assume that the actual hole you are drilling is not going to be on show once the handles are fitted , so before i came across a metal hole puncher , i used to cut a groove
or slit into the tang where i wanted the hole to be and it is far easier to drill the hole you need with an hss bit , cheap but slightly long winded way to do it , but it does work
you will need a dremmel type tool to do this though