Drilling Accurate Holes

When drilling alternative materials, it's important
to accurately center the hole in your project blank

Overview: There are lots of jigs on the market that can help you to produce accurate holes. These include X-Y vices, centering jigs, specially milled bits and even laser pointers to help you align the bit when working with curved blanks like antler. All of these jigs and tools work, but even if you use them consistently your bit may still wander when penetrating some materials. Back in the day before I began turning primarily for wholesale customers, I turned a lot of smaller items for the retail market.

Small projects like writing pens, bottle stoppers, fragrance pens, key rings and similar items were good to have on hand when doing retail art and craft shows. They were always good conversation starters and served as "bread and butter" projects to pay booth fees, as well as other travel related expenses. All of these projects required a hole to turn on the lathe and I've always enjoyed experimenting with new jigs and techniques to increase the accuracy of my holes.

One of the challenges you can encounter is called bit wander. When your bit wanders, the hole is centered on the top of the blank, but it veers off the center path and it exits near the edge the blank. In severe cases, the bit may actually exit through the side of the blank. It can be frustrating at times, as bit wander can rear its ugly head at the most inconvenient of times. Fortunately, there a few things you can do to help eliminate bit wander, so your holes will be straight and true.

X-Y vices make centering the blank with the bit very
easy. This model cost approximately $75.00 in 1997

Using Press Vices

If you use a drill press to drill your project blanks, an X-Y vice is a good tool to have to keep your blank secure making a hole. I've been using an X - Y drill press vice for sixteen years and it has served me well. X - Y vices allow you to move the blank in both the X and Y axis, as you are centering the blank under the bit. These vices clamp to your press table and are useful for holding a variety of materials.

Many other types of vices are available as well, from regular press type vices (no X - Y movement), to machinist vices, wooden hinge type holders bored to accept a pen or bottle stopper blank, as well as numerous other choices. No matter which vice you prefer, using a drill press vice will help you to produce straighter holes by keeping the blank from moving.

It's important to keep your bits sharp, so they can produce accurate, clean holes. If your bits are dull, replace them as soon as possible and store them properly to avoid damage

Various Bits

Drill bits have come a long way in recent years with new high-tech point designs that cut cleaner and exit with the bottom of the blank with little or no chipping, or tear out. These newer bits are far superior to the older split point bits and make penetrating difficult materials much easier. No matter what kind of bit you prefer to use with your blanks, it needs to be sharp.

If your bits are old or they have hit your press vice a time or two on a deep plunge, then it's high time to get yourself some new bits. If possible, use your new bits only for making a hole in turning projects and not for general home repair to help maintain their accuracy and edge life.

Center finders can help you quickly
locate the center on your project blanks

Center Finders

Center finders are a very useful jig to have when penetrating smaller blanks. By accurately finding the center of the blank, you know that you are getting setup as accurately as possible. This is especially important when your project uses small pen blanks, like the 1/2" size needed for some slim line pens. They are also just handy to have on hand and are inexpensive to purchase. Most center finders will accurately find the center of not only square turning stock, but round stock as well.

A New Protocol is Born

Even if you are using a good vice, with a brand new high tech bit and you have accurately marked the center of your blank, you bit can still wander. The variable density in the springwood and heartwood can sometimes cause a brand new bit to wander. Some alternative materials are also notorious for being difficult to drill accurately, as well as a few natural materials. One of the advantages of being a production turner is that you get lots of practice preparing blanks for projects.

You also gain a lot of experience working with various woods and alternative materials. Since I'm committed to continuous improvement of my production protocols, I always experiment with different techniques in an attempt to achieve the highest accuracy possible on a wide variety of materials. My "Reset Drilling Protocol" was developed after much trial and error in order to increase the accuracy of my holes; no matter what material I used.

This protocol came about through a lot of trial and error with different blank penetration techniques, speed tests and experiments using every type of bit I could get my hands on. After all of the dust had settled, I found that by resetting my bit after the initial penetration of the blank, bit wander was virtually eliminated.

Reset Drilling Protocol

Note: This is an easy protocol to implement, but it does require an X - Y vice so you can easily move the blank as necessary to re-center the bit to compensate for any wander when penetrating the top of the blank.

The front of the bit can be used to quickly
square the blank in your drill press vice

Securely lock the blank into your X - Y vice and move the X and Y adjusting levers to center the bit with the marked center on your project blank.

Rotating the front adjustment
lever moves the blank up and back

Rotating the side adjustment
lever moves the blank left and right

Once the blank is centered with the
tip of the bit, lock the front grub screw

Once you have locked the side grub
screw, you are ready to begin drilling

Make sure the blank is sitting square in the jaws of the vice. If necessary, use a small machinist's right angle jig to orient the blank correctly. If you do not have a small 90 degree square, simply loosen the jaws slightly on the blank and lower your bit down the front side of the blank. Adjust the blank until it is straight up against the side of the bit and tighten the jaws securely. If your drill press table is setup square to the post column, your bit can act as a makeshift alignment jig. If necessary, re-center the blank with the point of the bit using the X- Y levers.

Make you initial penetration into
the blank no deeper than 1/4 inch

When you're ready to begin, turn the drill press on and enter the top of the blank very slowly. The idea here is to let the bit cut a clean entrance hole in the top of the blank. When the entrance hole is cut, gently lower the bit into the top of the blank, but only penetrate to a depth of 1/4".

When drilling, periodically check and remove
any swarf on the flutes of the bit

Withdraw the bit and turn the press off. Rotate the bit until you can clearly see one side of the bit and manually lower the bit down into the drilled hole. As the bit enters the hole, look to see if it goes in straight, or if it is pushed off to the side slightly. If you see the bit goes off to the side as it enters the drilled hole, loosen both of the X and Y locking grub screws and adjust the blank using the levers until the bit enters the hole straight and true.

Move the blank as necessary to reset the
bit so it enters the blank straight and true

Move the bit in and out a few times to make sure that it enters the hole without veering off to one side. A good strong light is needed to clearly see the bit entering the hole and if it goes in correctly or not. If you don’t have a supplemental task light for your drill press (the built in light is insufficient to determine bit wander), now is a good time to buy one. The magnetic task lights that Craft Supply sells (Moffitt Lights) are very well made and will accept a 100-watt bulb. The magnetic base is a plus, since you can move it around to different equipment as needed.

Lock everything back down and drill your hole using the reset center point. In practice, resetting the bit takes about 15 – 20 seconds, not much time at all to prevent wander. Of course, your bit will only wander occasionally, but if you get in the habit of checking it according to my protocol, you will be a happy camper when you turn your blank over to see where the bit exited the blank.

Note: If you see that the bit enters the blank correctly, no problem – continue making the hole according to your current setup. If however, you see the bit wanders slightly as it enters the hole, reset the bit according to the above protocol.

This protocol has really helped me through the years and I know that it will help you as well. The next time you need to drill a hole in a project blank, use this protocol and see how easy it is to increase the accuracy of all of your holes. Good luck!



