Did your 1/4" drill bit just break in the middle of a remote project? Has your 1/2" bit wandered off from the set? Do you have a bunch of dowel pins of a weird in-between size? Planning on doing an iffy drilling operation that might damage a bit? Are you tired of hypothetical situations?
If you have some nails with you, you might still be in luck. It is super quick to make rudimentary bits that go through soft
wood really, really well. I'm calling them "spade bits" here though they are closer in shape to masonry or glass-cutting bits I suppose.
Requires:
- Hammer
- Hard surface (like another hammer maybe)
- Nails (16d used here)
- Metal file (or maybe very hard stone)
- Drill
For the larger sizes, up to say 1/2" (~12mm) if you are using 16 penny nails, flatten the head side between your hammer and a hard place (I used a small hand sledge). With the same size nails, sizes between about 1/4" (~6mm) and 3/8" (~9mm) can be more easily made by flattening the pointed side instead and then cutting off the head of the nail. Depends on the nail head type, but you can make a bit anywhere from just larger than the shank diameter to about three times the shank.
Now with the drill blank chucked up in a hand drill, spin it against a metal file at the angle you want the blades to be at. Try to move it around the file a bit so you don't build up chips and/or ruin the temper of the file. The bevels can now be added on the back side of the bit using the metal file by hand. Since nails are about the mildest steel around, this goes pretty quick. If you want to get fancy, you can add a second, steeper bevel at the edge like on a knife.
I guess that's it. The cutting edge wings can be filed down pretty precisely to adjust the diameter of these bits, and they are so fast to make and to sharpen that you don't need to worry about wrecking them. They also drill through softwood extremely well, better than a regular twist bit I think. I did about 50 holes 2" deep into pine with the 8mm one and the edge still looked fine. When the edge does get messed up, about two passes with a file and you are good to go. Just for fun I tried them on a red brick and a soft rock outside, and they dulled immediately... wood, plastic, and maybe soft sheet metal (see pictures) only I think.
I have a thing coming up that is going to use some various sized dowel pins and figured I would get this technique down first.
This is part of the MoPID series of permaculture innovations that I am working on during my time at
Wheaton Labs. Check out the
thread if you'd like to follow along.
Oh one more thing! If you make these bits left-handed instead, you can give them a shot for removing screws with stripped heads. I don't have any around to try it on, but left-handed twist drill bits do this much better than something like an EZ Out in my
experience. Also, if you don't have a metal file you can just flatten the initial blank and use that... It will half-cut half-burn its way through but this might work in a pinch.
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