Removing BROKEN drill bits, that is!
First off, and you probably don’t want to hear this – especially if you have a broken bit – try to prevent breakage in the first place. Be sure to lubricate your drill bits and burs with either Bur Life stick or liquid, Beeswax or oil. Secondly, the best way to avoid broken bits is to lower the rpm of the tool you are using. That means: DRILL SLOWLY - especially with smaller drill bits. Thirdly, insert the drill bit as far into the tool as possible – up to, but not past, the cutting edge (flutes). There, no more broken drill bits! Well, not really…
Note: In the American system of drill bit measurement the smaller the number of the drill bit, the smaller the bit is, i.e.: a #80 is .343 mm and a #1 is 5.791mm. BTW, Jewelers generally use twist drills. European bits are measured in millimeters so with this sensible and logical system of measurement, the lower the number, the smaller the bit. Conversely, the higher the number the bigger the bit. I vote for changing to the metric system. Where can I leave my ballot? Drill bit sizes are not the same as gauge sizes. Don’t get me started on gauge…!
So, now on to the solution. Generally, for the jeweler, there are three ways to remove a drill bit that has broken off. If there is enough drill bit showing, try to grab the protruding part of the drill bit with serrated jawed pliers. Twist in the opposite direction in which you were drilling. If you’ve got a big chunk of drill bit hanging out of the metal, go ahead and try to untwist it first – before the chemicals. Usually, though (especially with the smallest of drill bits) the un-embedded piece breaks off and the embedded part stays stuck. So, now what?
Warning: Do not immerse stones into either the pickle or the alum solution. Test a scrap of your metal first, to ensure that either chemical will not damage the metal. These recipes are safe for sterling silver, fine silver, brass, bronze and copper (I know, I’ve removed bits from all 5 metals using the following techniques). I’ve noticed no effect, to the metal, from using alum.
Soak the piece with the drill bit stuck in it, in pickle. Leave over night. As an alternative method for chemical removal, follow the instructions for “Alum” below.
Note: If you leave the metal in pickle overnight, there will be a very slight etching of the metal, especially with copper. I mean slight! Nothing that a little buffing can’t repair.
My favorite method: This method requires Alum (available in the spice section of your local grocery). Put about a tablespoon of alum into a non-metal container with about a 1/2 cup of hot water. You want an alum saturated mixture. Lots of alum. A Warm or boiling alum/water mixture works MUCH, MUCH faster. Without heating the alum, it took days for my drill bit (stuck in acrylic) to dissolve. You can put the alum mixture and the piece into a glass jar and place in a crock pot (that contains water) or in a pan on the stove (that contains water) – just like using a double boiler, for you chefs out there. It can take 1/2 hour or more so, the crock pot is a good choice here. If doing this on the stove top – please watch it so you don’t burn your pans, crack the jar and fill your house with unpleasant odors.
That’s it – happy de-drill bitting (nope – not a word).