Make: Tools, page 13
As described in Chapter 8, I think it’s a good idea to proceed in small steps when you’re drilling a 3/8" hole. This is less important when you’re dealing with hardwood than when you’re drilling into pine, but small steps enable you to correct errors as you go along.
The first step is to use an awl to mark the center of your dowel. Finding the center can be tricky, but you can use your ruler to check that the point of the awl is at an equal distance from each side. Then turn your ruler and check again from other directions.
After you make a hole with the awl, put a countersink in the drill and create a cavity as shown in Figure 9-8. You should do this a little at a time, pushing the drill to one side or the other if the cavity isn’t quite centered.
Figure 9-8. A cavity created with a countersink will make drilling a hole much easier.
Now use a ¼" bit to start a vertical hole. If your drill doesn’t have a bubble level to tell you that it’s vertical, you should pause frequently and check the bit from the front, the side, and then the front and the side again, as it goes deeper. Don’t press too hard, and remember to pull the bit out occasionally to get rid of the accumulated wood chips. The more slowly you proceed, the better your chances are of getting it right.
Remember that the spiral flutes on a drill bit are necessary to excavate wood particles from the hole that you are drilling. Therefore, you don’t normally drill beyond the extent of the flutes. If the smooth, round shank of the bit enters the hole, it will start to get hot quite quickly.
In Figure 9-9, after I made a hole as deep as possible with the ¼" bit, I stood a screwdriver in the hole to check it was vertical.
Figure 9-9. A screwdriver in the ¼" hole verifies that it was drilled vertically.
Now for the interesting part. Switch to your 3/8" bit and run the drill slowly. Touch the bit to the ¼” hole very gently. Making the 3/8" hole is a very different experience from making the ¼" hole. The bit will really grab the wood if you let it. Be cautious and don’t hurry.
Your goal is to drill downward for just over 3", which a typical 3/8" bit should be able to manage without any trouble. Clean out all the debris, and the result should look something like Figure 9-10. Not perfectly centered, but close.
Figure 9-10. Part one of the task completed.
Now you need to loosen the clamps and take the jig apart, to clean out all the fragments of wood. You don’t want any debris in the way when you tighten the jig again.
Turn the dowel upside-down, clamp it, and repeat the drilling sequence from the other end. I doubt that the two holes will meet precisely, but they don’t have to, so long as they overlap to some extent.
You may find that when you break through from one hole to the other, the bit will grab the dowel and may start turning it, no matter how tightly you clamped it. This is less likely if you are keeping the flutes of the bit clean, but if it does happen, do not hold the dowel to stop it from turning! There’s a risk that the dowel may split open, at which point you will find yourself holding the drill bit inside it. That would be a very unpleasant experience.
If the drill jams, put the drill into reverse, pull the bit up, then return to forward gear and increase the speed. You should be able to make the transition from one hole to the other inside the wood.
No doubt you’ll want to unclamp the dowel and look through it to make sure the holes are aligned—in which case, you’ll probably be disappointed. The 3/8" bit will have pushed the last bit of sawdust into the lower hole, instead of extracting it. You may need to use a screwdriver or pencil to clear the dowel.
Blow through it, but be careful not to inhale when your mouth is close to the dowel. You don’t want to breathe sawdust. Turn your head to take a breath of clean air, then blow through the dowel. If it still isn’t clean inside, you’ll need to apply the drill again.
Making the Mouthpiece
A Swanee whistle is closed at the bottom, and all the air will emerge through a hole that you cut into the side of the dowel. The part of the whistle which you blow into is called the fipple, and the hole where the air emerges is the fipple hole. (That’s a real word—I didn’t make it up. In fact you can find entire web sites online, dedicated to discussion of fipple geometry in penny whistles. It’s not a trivial matter.)
Getting the fipple to work is tricky, because tiny variations make a big difference, but if you’re patient, I think you’ll get a sound out of it. I’ve completed this project three times, and I always managed to make it emit a high-pitched whistle in the end.
The first step is to make a saw cut 1" from the end of the dowel, with the jig turned on its side to hold the dowel horizontally, as shown in Figure 9-11. Be very gentle with this cut. You don’t want it to go too deep. As soon as the saw reaches the hole inside the dowel, stop immediately.
Figure 9-11. Making a vertical cut that will become the top end of the fipple hole in your whistle.
Now you need to make a diagonal cut to meet the vertical cut, and I think the easiest way is with a utility knife, as shown in Figure 9-12. Keep the dowel clamped on the bench and push the knife away from you, keeping your other hand out of the way.
Figure 9-12. Beveling the fipple hole with a utility knife. Be sure to cut away from you. Keep your other hand away from the cutting site.
The hole has to be as clean as possible. Ragged edges will diffuse the air stream and prevent your whistle from resonating. Use the knife very delicately to trim the edges of the hole, as in Figure 9-13.
Figure 9-13. Trimming the edges of the hole.The knife is now facing you, so use it very gently, and do not apply much force.
The next step is to restrict and direct the air flow through the mouthpiece and under the hole in the side of the whistle. To do this, you need to plug the mouthpiece with a 1" length of 3/8" dowel that has a flat side, as shown in Figure 9-14.
Figure 9-14. The basic principle of fipple design is to restrict the air flow and direct it under the hole in the side of the whistle.
You can sand a piece of 3/8" dowel to make a flat spot on it. This is most easily done as in Figure 9-15, before you cut the 1" section.
Figure 9-15. A flat spot on the 3/8" dowel, created by sanding it.
Insert the 3/8" dowel partially into the upper end of your whistle, as shown in Figure 9-16. Don’t push it in all the way. Blow into the end with the plug in it, so that your breath goes through the thin gap between the plug and the hole that you drilled. Block the the opposite end of the dowel with your finger. If all you get is a vague, breathy sound, move the plug a fraction further in or further out. Still no note? Sand the plug some more and try again. The dimensions are critical, and the force with which you blow will also have some effect. You shouldn’t need to blow hard. In fact, you are more likely to get a sound if you blow very gently.
Figure 9-16. Adjust the depth of the plug and test the whistle repeatedly.
Be careful not to inhale while your mouth is over the dowel. The plug should fit tightly, but just in case it is loose, you want to avoid the risk of drawing it into your mouth.
When you finally have a whistling sound, you can cut the plug so that it is flush with the end of the dowel, and glue it in place. Then sand it to make a better-shaped mouthpiece. See Figure 9-17.
Figure 9-17. A beveled mouthpiece on the whistle.
Finally, cut a 3" piece of your 3/8" dowel and slide that into the other end of the whistle, as in Figure 9-18. By moving it in and out, you’ll vary the whistling pitch.
Figure 9-18. The finished whistle.
A larger whistle would create a deeper, louder, mellower tone. How could that be made? Well, instead of wood, how about using a plastic tube, such as a piece of PVC water pipe? I’ll begin to explore the whole topic of plastics in Chapter 15.
Chapter 10
A Basic Box
NEW TOPICS IN THIS CHAPTER
■ Types of screws
■ Types of screwdrivers
■ How to design in 3D
■ Types of corner joints
YOU WILL NEED
■ Two-by-four pine, any condition, length 18"
■ Square dowel, hardwood, 1/2" x 1/2", length 18" Square dowel, 3/4" x 3/4", length 3"
■ Plywood, 1/4" thick, size 12" x 18"
■ Wood screws, #6 x 5/8", flat head, Phillips, quantity 20
■ Wood screws, #10 x 1", flat head, Phillips, quantity 3 (optional)
■ Screwdriver, Phillips size 2, or electric screwdriver and bits (optional)
Also, as listed previously: Tenon saw, miter box, trigger clamps, ruler, speed square, rubber sanding block, work gloves, awl, masking tape, utility knife, electric drill and drill bits, countersink, dust mask (optional), safety glasses (optional), utility saw (optional), plywood work surface, sandpaper, and epoxy glue and hardener.
Check the Buying Guide on page 248 for information about buying these items.
The concept of a screw thread is more than 2,000 years old. The great Greek inventor Archimedes developed a massive wooden screw as a method for raising water from a river. Much later, in the 1800s, screws and bolts became an essential part of the industrial revolution. The modern world, as we know it, would not work without them.
This project uses screws where glue wouldn’t be as strong, and it introduces you to design issues associated with one of the world’s most basic shapes: a rectangular box.
You’ll find facts about screws in the Screws and Screwdrivers fact sheet on page 123. I’ll also mention the option to buy an electric screwdriver, but for this project, you only need a manual screwdriver with a medium-size (number 2) Phillips head.
A Screw and a Square Dowel
Before I get into the project itself, I want you to do a little wood-splitting experiment, like the one when I discussed nails in Chapter 4. You need a 3" piece of ¾" x ¾" square dowel (maybe left over from previous projects), a 3" piece of ½" x ½" square dowel, a screwdriver, and three wood screws. They can be 1" long, #10 size, as shown in Figure 10-1, although any #10 screws will do.
Figure 10-1. A screwdriver tip and screw for a wood-splitting experiment.
The #10 classification describes the thickness of the shank of the screw. In a wood screw, the shank is the smooth part directly under the head (like the smooth section of a drill bit). Unlike nails, which tend to be fatter when they are longer, a #10 screw is the same thickness no matter how long it is. You’ll find a table of screw sizes in Figure 10-34, in the fact sheet at the end of this project.
Begin with the piece of ¾" square dowel. How can you drive the screw into it? Well, you can just press hard, turn the screwdriver, and hope that the screw will cooperate—but this is not easy, especially if your dowel is hardwood.
You can whack the screw with a hammer to embed the tip of it in the wood, but a better idea is to use an awl. Set the screw aside, and push the sharp tip of the awl into the wood, about ¾" from the end. Lean on it hard, and wiggle it around to make a cavity.
Now you should find that starting the screw will be no problem, but you’ll need to use more strength as it goes in deeper, and I’m betting that the wood will split, as in Figure 10-2. Screws, like nails, do tend to split wood, especially if the screw size is relatively thick.
Figure 10-2. What happens when you force a #10 screw into a small piece of ¾" x ¾" dowel.
A #10 screw is really too big for this job. But there’s a way to make it penetrate a hardwood ¾" dowel if you really want to. You drill a pilot hole.
The Importance of a Pilot Hole
When a drill makes the hole, it doesn’t compress wood significantly. It extracts some of the wood as tiny chips. The hole then provides space for the body of the screw, while the threads of the screw, which do the real work, cut into the material that remains around the hole.
Try using a 1/8" drill to make a pilot hole for another #10 screw. If you’re wondering why I chose 1/8", a larger pilot hole would not allow the screw to get a firm grip, while a smaller pilot hole might still allow the screw to split the wood. You’ll find a table of recommended hole sizes in Figure 10-34.
Now when you insert the screw you should find that it slides in more easily and does not split the wood, but is still secure. With a 1/8" pilot hole, you can even embed a #10 screw in a skinny little ½" square dowel, as in Figure 10-3.
Figure 10-3. If you drill a 1/8" pilot hole, a #10 screw can even fit into a ½" x ½" square dowel without splitting it.
In Chapter 8, when you were building a drill rack, I suggested the option of using pilot holes with finishing nails. If you are using screws in small, precise projects, pilot holes are not just an option anymore. They are essential.
Corner Blocks
The current project is for a basic box, because the shape of a box is fundamental in fabrication work. Each of the drawers that slide out of your kitchen cabinets is constructed as a box shape. A cupboard is basically a box. Your chess set may be packaged in a wooden box. Even a bookcase is box-shaped.
Your first, basic box will be ultra-simple. The sides, bottom, and lid will be made from plywood that is ¼" thick. Small blocks of square dowel, ½" x ½", will connect the sides at the corners.
Figure 10-4 shows a rendering of the design for this box with its front side and its lid missing. Screws will be driven through the plywood and into the blocks inside the corners.
Figure 10-4. Box construction using corner blocks.
There are many other ways to make corners, and I’ll list some of them at the end of this project. But blocks are the easiest option.
Cutting Plywood
I designed this box to be small, to minimize your sawing, but I will assume that you may be starting with a relatively large piece of plywood.
When I visited my small-town local lumber yard to see what they had available, they offered me some shopworn, slightly scratched ¼" plywood with a soft pine veneer that looked as if it was guaranteed to splinter. Could I really build a small box with that? I decided I should find out, just in case you ever have a similar experience. They sold me a quarter-sheet measuring 48" x 24".
Even if you buy better-quality plywood, it often has ragged or worn edges. Therefore, it is standard procedure to make your own edges by cutting inside the edges created by the lumber company.
Figure 10-5 shows the first step. The ragged red lines indicate rough cuts, without worrying about splintering the underside of the wood, because you can’t easily use a piece of sacrificial wood under a cut that’s 16½" long.
Figure 10-5. The first two cuts are rough cuts.
Incidentally, here’s a quick tip:
■ If your saw tends to jam or squeal while you are making a long cut, take hold of the free end of the wood and twist it up and to the left, away from the cut, as shown in Figure 10-6. This will relieve the pressure on the saw blade. Just be careful to keep your fingers away from those saw teeth.
Figure 10-6. Bend the wood up away from the cut to relieve the pressure on the saw.
Now that you have a manageable work piece, you can extract three small rectangles from it. Figure 10-7 shows the cuts that will give you the first rectangle. I’ll get to the second and the third in a moment. My idea is that none of the cuts should be longer than 6", so that you can make them easily with your tenon saw.
Figure 10-7. The first of three rectangles from your work piece.
First make a clean cut along line A, about ½" inside the edge, and roughly parallel with it. The precise position is not crucial. Use sacrificial wood under the plywood as in Figure 10-8.
Figure 10-8. Cutting along line A.
After you make a nice straight cut, you can use this as your reference edge. This means you will make the next lines and cuts with reference to it. All the measurements for this project will be made relative to that edge, because the other edges were either rough-cut or factory-cut, and are not entirely trustworthy.
Now that you have your reference edge, make two marks on it that are 4" apart, as shown in Figure 10-9.
Figure 10-9. Two marks, 4" apart, on line A.
Place your speed square against the reference edge, and draw the two 6" lines that were labeled C and D in Figure 10-10. Use your pencil to make a mark at each 6" location.
Figure 10-10. Measure 6" along the lines that were labeled C and D in Figure 10-7.
Draw line B between the two 6" marks that you just made, and then extend line B out to the side edges of your strip of plywood, as shown in Figure 10-11. (Refer back to Figure 10-7 if you’ve forgotten which line is line B.) You just drew a rectangle based on your reference edge. So long as your speed square is accurate, your rectangle should be accurate.
Figure 10-11. The perimeter of the first rectangle has been outlined.
Cut along line B, as shown in Figure 10-12. When the cut is done, set aside the remainder of your work piece, rotate the rectangle that you are working on, and lines C and D are now short enough to be cut edge-to-edge with your tenon saw. Remember to cut outside the pencil lines at each step.
Figure 10-12. Cutting along line B.
Retrieve the remaining portion of your work piece, which will enable you to make your second rectangle. In Figure 10-13, you’ll see that line B is your new reference edge. Make two marks on it, 3" apart. Then you can use your speed square to draw lines for cuts E and F, each 5½" long. Then draw line G and cut along it. Finally cut E and F. This is the same system that you used for the first rectangle.
