41 - Fold-Down Drafting Table, страница 10
Crank Assembly SHOP PROJECT At this point, the reel is enclosed by the housing. But it's not ready to use yet. It still needs a crank so you can wind the hose onto the reel. The crank consists of two pieces: an arm that fits over the shaft, and a handle that turns the crank, see Fig. 5. more plumbing. But first there's a bit more plumbing to do. To prevent air from escaping from the end of the shaft where the crank is located, you'll need to thread on a coupling and install an end plug. Note: I threaded a male plug that accepts a female coupler to the opposite end of the shaft, see Step 1 on next page and Exploded View on page 7. arm. With the fittings in place, you're ready to add the arm (I). It's nothing more than a piece of •"W'-thick hardwood. (I used maple.) To allow the handle to spin freely once it's attached, there's an oversize hole drilled near one end of the arm, see Fig. 6. And a large (7/8"-dia.) hole near the opposite end is sized to fit tightly around the coupling. But even with a tight fit, the arm could still slip as you turn the crank. So it's held in place with machine screws and lock nuts. The screws pass through holes in the edge of the arm, see Fig. 6. To allow the screws to apply clamping pressure, I cut a long-kerf in the arm. This way, the arm will "pinch" the coupling as you tighten the lock nuts. All that's left to complete the arm is to cut it to final shape. The narrow end is formed by cutting a gradual taper on each edge. Then I sanded a gentle curve on both ends, see Fig. 6. Now it's just a matter of attaching the arm. To provide extra insurance against slipping, it's held in place with epoxy. HANDLE. Before attaching the arm, it's easiest to add the handle (J), see Fig. 5. This is just a dowel that's screwed to the arm. Why doesn't the handle come unscrewed? Because the screw passes through the oversize hole in the arm. But it threads tightly into a pilot hole drilled in the end of the handle. As a result, the handle spins freely (without loosening) as you turn the crank. 10 ShopNotes No. 41 |
