Drilling The Pilot Hole

After the shank hole is drilled, a smaller pilot hole can be drilled in the back piece to anchor the threads of the screw and prevent the wood from splitting.

To mark the location of the pilot hole, the usual practice is to hold or clamp the front piece in the correct position over the back piece. Then an awl is slipped through the shank hole to mark the centerpoint of the pilot hole.

This can be troublesome because the awl may not be exactly centered in the shank hole, or it may slide off center because it hits a hard part of the grain.

To get a more precise location for the pilot hole, I use the following method. First, use a brad point bit to drill the shank hole. Then hold the second board in place. Now. with the brad point bit in the shank hole, just give it a little tap or twist, so the point of the bit marks the precise center-point for the pilot hole.

diameter of pilot hole. The pilot hole should be about the same size or a hair smaller than the root diameter of the screw. One trial and error method to determine the right drill bit is to hold bits up in front of the screw until you find one that allows the root to just barely show on both sides of the bit.

depth of pilot hoi£. How deep should you drill the pilot hole? That depends on the type of wood you're screwing into.

In softwood, I usually drill the pilot hole only half the length that the screw will be into the anchor piece. That's all that's necessary to keep it from splitting.

Hardwood Ls more likely to split, so 1 drill the pilot hole to the depth where the screw begins to taper to a point (about two threads short of the end.)


The pilot hole and shank hole take care of the mechanics of the screw joint, but the

The year was 1900 when Peter Robertson (a Canadian tool salesman) cut his hand with a screwdriver while he was driving in a standard slot-head wood screw. This mishap was the beginning of a newT type of screw7.

After experimenting with several new designs, in 1907 Robertson patented a screw with a slightly tapered, square hole in the head. To drive it in, he used an odd-looking screwdriver with a small square head that fit snugly in the hole.

Robertson launched his company by advertising that his screws "positively cannot slip and cut the fingers or disfigure costly furniture or wood."

Although they've been popular for years in his native Canada. Robertson's screws have never caught on in the U.S. That's unfortunate because there are a number of advantages to square drive screws.

cam out. One of the most aggravating things about working with standard w ood-screws is "cam out." Both slotted and Phillips head screws often strip out (cam out) just as you're tightening them down snug. Howrever, with Robertson screws, it's almost impossible for the screwdriver to cam out of the square recess.

Another characteristic I like is that the screw stays on the end of the screwdriver final appearance is determined by a countersink or counterbore.

countersinking. If you want the screw head flush with the surface, it has to be countersunk. To determine the correct diameter (depth) to drill the countersink, turn the screw upside down and fit the head into the countersink. The screw will be flush with the surface when the head just fits into the countersink.

In softwood, the diameter of the countersink (on the surface) can be a little smaller than the diameter of the screw head since softwood will compress as the screw is tightened down. On hardwood, the countersink should be almost the size of the screw head.

counterbore. If you want the screw-head below the surface so it can be covered with a plug or putty, you have to drill a counterbore. I use a brad point bit to drill the counterbore before drilling the shank hole. Then the shank hole can be centered in the point left at the bottom of the counterbore.

pilot bit sets. All of this drilling requires three bits: one for the counterbore or countersink, one for the shank hole, and one for the pilot hole. Or you can save time and do it all with a pilot bit set. On the next page, we've taken a look at some of the most common pilot bit sets on the market.

as though it's magnetized. You can turn it upside down and it won't fall off. That's great for tight spots.

drivers. Although you need a special square-head screwdriver, one size fits No. 6, 8. and 10 square-drive screws. (All use a No. 2 driver).

lo-root. In addition to the square drive design, Robertson screws are also available Lo-Root (like particle board screws). This combination of square drive and Lo-Root make them ideal for woodworking, see Sources, page 24.

recex. If there's a problem. I guess it would have to be: Will square drive screwdrivers still be available 25 years from now when the project needs to be repaired?

That problem has been solved already. A variation of the Robertson square drive, called a "Recex," has been developed. It has a square recess for driving with a square driver. But it also has the "star" pattern of a Phillips head so it can be removed with a Phillips drive.



Woodworking Tools and Installation Tips

Woodworking Tools and Installation Tips

There are a lot of things that either needs to be repaired, or put together when youre a homeowner. If youre a new homeowner, and have just gotten out of apartment style living, you might want to take this list with you to the hardware store. From remolding jobs to putting together furniture you can use these 5 power tools to get your stuff together. Dont forget too that youll need a few extra tools for other jobs around the house.

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