How to make holes in things - Embedded.com

How to make holes in things

Many of the pictures in this blog started off in my recent Favorite & Unusual Tools article. However, that article grew so quickly that I had to split it up into two. The fact that so many of the tools described were for making holes in things gave me a convenient title for this follow-on article.

There are many different ways to make holes in things. Most of them involve drilling or cutting in some way, but there are other techniques. Years ago, the husband of a friend of my wife came to me for help. He was a civil engineer, but also very gifted mechanically, and he had a roomful of lathes, milling machines, and the like. He wanted help to build a spark erosion machine. This works by repeatedly bringing a shaped metal electrode onto a workpiece. Every time this happens there is a spark between the electrode and the workpiece. The electrode is immediately withdrawn and then brought down onto the workpiece again, and again, and again. Each spark erodes a tiny part of the workpiece. If you do this fast enough and long enough, you will slowly but surely erode the workpiece away.

You can use this technique for making holes of any shape in the workpiece (just shape your electrode to suit), or for removing (by eroding away) a tap or drill that has broken off inside a valuable workpiece. I gave him a lot of the components he needed to implement this unit — notably a stepper motor for driving the electrode to and from the workpiece, along with some of the components needed for the driver electronics. Alas, I left Zimbabwe before he had completed the project and I have never seen it in action. But I think it was this article that he worked from. The original document is dated 1976, so there is a lot of scope for updating the electronics. For example, a small microcontroller could be used to drive the stepper motor, detect electrode contact, and give an LCD readout of the depth. I have added this to my list of things to do when (if) I retire, because I'm not likely to get to it before then.

In the meantime, I have used many more conventional ways of making holes. Most members of the EETimes community will probably own a drill or two — perhaps one of the ubiquitous cordless drills, which are very handy, and maybe a mains-powered electric drill. Has anyone noticed how drills — particularly cordless ones — are looking more and more like running shoes? Here's a prime example:

That said, the newer tools are much lighter and have better battery life than the older ones (as a result of their lithium battery packs) and they also have some very nice features. But I'm probably a bit of a fuddy-duddy, because I prefer my drills to be monochrome and not overly decorated.

It is features that sometimes help you get the job done. In a good drill, for example, I'd look for variable speed, reversibility, variable clutch, hammer action, keyless chuck, and maybe a light to illuminate your work. In a cordless drill, you want quick battery charging and maybe a spare battery pack if you do a lot of work.

Side rant: Did anyone notice how many drills — and other rechargeable items used to advertise themselves as quick-charge, but had non-limited chargers that would destroy the battery if you left them on longer than a few hours? This is less of a problem these days now that most things use lithium batteries — which will destruct spectacularly if overcharged, thereby forcing the designers to account for this — but it was rife in the old NiCd/NiMH days. (End of rant.)

The usual way of making a hole in something is to use a drill, which means you will also need a drill bit. These come in a vast array of sizes and types. The usual set of bits, which go up to 1/4, 3/8 or 1/2 inch in diameter, are fine for most jobs, but you will almost certainly find a job for which they are not big enough or long enough. I've acquired a few of the more unusual bits (and sets of bits) over the years, and I will show you a few of these.


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