Useful tips for drilling holes

Press, 13 March 1986, Page 25

Useful tips for drilling holes

One of life’s little disasters when you are drilling holes is to drill too deep. Maybe the hole will be so deep it won’t hold a screw tightly. Even worse, your bit can pop out the back side of your work, tearing it up and ruining it.

There are several different ways to prevent this kind of trouble. A few of these are pictured in the sketch.

A quick and simple solution is to wrap a piece of tape around the bit, marking the depth at which to stop. When I use a tape marker, I like to leave a tab of tape hanging out like a flag as shown in the sketch. This makes it easy to remove when I am finished. It also makes it easy to tell when you have drilled deep enough. The flag begins to rub on the work and signals you to stop. The tape trick is fine if you only want to drill a few holes to a specific depth, but when you have to drill several, or dozens (as you might when making holes for adjustable shelf supports), it’s better to have some kind of physical stop. This makes

it impossible to drill too deep, eliminating any chance of error.

It also speeds your work, by letting you drill quickly without worry of overshooting your mark. There are special depth stops you can buy just for this purpose. One type is adjustable to fit bits of various sizes. You slide it on to the bit, position it for the proper depth, and tighten a collar so the collar grips the bit. One size doesn’t fit all, but two of them, one large and one small, should take care of any bit from I.smm to 12mm.

Another type is not adjustable to fit different bit sizes. You have to buy one for each bit. I find it easier to keep track of two adjustables than seven non-adjustables. The non-adjustables have another disadvantage: You need a little Allen wrench to lock them in position — another item to fool with and lose. Most of the time, I don’t use either of these shop-bought stops. I make up my own as the need arises, using a scrap of wood.

Here’s how: Start with a scrap of wood about 25mm longer than your bit, and about 20mm square. Slip your bit in the chuck and drill a hole through it lengthwise. Now let’s say you want to drill 15mm deep. Make sure the block is shoved down tight against the chuck. Measure 15mm down from the tip of your bit and mark that point on the block. Slip the block off the bit, cut it at the point you have just marked, and slip it back on the bit. You are now ready to drill. All this takes about 30 seconds — as long as you’d spend hunting for and adjusting a shopbought stop — and it doesn’t cost you a cent The wood stop has another advantage — it cannot slip up the bit and go out of adjustment as long as you insert -your bit all the way into the drill’s chuck.

You can keep the stop block around for future jobs if you like, but I usually throw mine away and make new ones whenever they are needed.