In jewellery making, sometimes you need to drill holes in metal sheet, to insert a jumpring or earring post, to pass the saw through so you can cut larger designs or to use rivets.
Even for those who have yet to venture into soldering but want to work with sheet metal, this is a basic but important technique to acquire because it allows you, among other things, to join several elements through the use of rivets.
Before drilling you should mark the puncture location with a pencil and then use a metal punch, like the one pictured above, to make a small indentation in the metal so that the drill doesn’t skid away. Just tap the punch with a hammer over the pencil mark.
The kind of drill used in jewellery making are usually very thin. The most common is probably 1mm thick but according to the project it may be necesarry to use 0,8 mm or 0,7 mm drills. This means the drills are fragile and easy to break if you put too much pressure on them.
There are several different tools that allow you to drill sheet metal. The most tradicional one is the pump drill,
The pump drill has a horizontal bar attached to a central drill Shaft by two bits of cord. When you turn the horizontal bar, the cord wraps around the central shaf. By pulling down the bar, the shaft spins, causing the drill to spin as well, creating the hole.
The pump drill is not an easy tool to use at first. It requires some practice and can cause some frustration. However, it has the advantage of being a very light tool and easy to control, once you get the hang of it, which reduces greatly the risk of breaking any drills. The main downside is that it takes too long to drill a hole, so it’s not very practical when you need to make several of them.
For those who don’t want to buy any specific tools, a simple electric drill or dremel will do. Just make sure it has adjustable speed, if possible with a trigger type button, because the drill works best at low speed..
It’s also important not to put too much pressure on the drill. Since an electric drill is somewhat heavy, it’s harder to maintain it perfectly vertical throughout and with the extra weight it’s much easier to break the thinner drills.
My favorite drilling tool, however is the flex shaft. It’s not as heavy as a drill and gives me a lot more control. The speed is managed by a pedal and the hand piece isn’t heavy so it’s easy to keep it steady.
Before drilling it’s necessary to lubricate the drill so that it spins better and to prevent it from heating up too much, which might also contribute to a break.
To lubricate the drill I keep a small plastic box with an oil soaked cotton ball. All I have to do is touch the drill to the cotton ball and it’s lubricated. The oil can be clear machine oil, like the kind used for sewing machines, or even olive oil.
Drilling should take place over a wood surface that you don’t mind poking a hole through. So it’s not a good idea to drill directly over a table, unless you have no love for it. You shouldn’t drill over a metal surface because the drill may break on contact with the metal. I use a section from a thick wood beam for all my drilling but some people drill directly over the bench pin.
The lubricated drill should be kept vertical and you should apply mild pressure but not too much. Too much pressure or changing the angle of the drill may break it, especially if it’s thin. It’s a matter of practice.
As I’ve mentioned before, the drilling speed should be low. At high speed the drill spins but doesn’t really remove any metal. To know if you’re actually drilling you should look for metal shavings coming out of the hole.
Sometimes you get halfway through the hole and the drill doesn’t seem to be doing anything anymore. This happens mostly with thicker metal or harder metals such as brass. In these situations I like to tap the punch into the hole once more. it seems to help the drill go a little further. You can also turn the drill in a small circular motion but only if the size of the hole doesn’t need to be too precise because it may stretch it a bit at the top.
Once you’ve drilled to the other side of the metal it’s common to have a little bump at the back. This bump should be filed away until the sheet is smooth and straight.