Step 19: Make the pulley wheel: prepare the groove and flanges
- 1" length of 1-1/4" PVC pipe.
- Paper towel.
- 5-1/4" of 1"-width 3M gray nonslip tape.
- PETE food tubs with curved walls.
- Scissors or box knife.
- Marking pen.
- 1-3/8" fine-tooth hole saw.
In rigging terminology, a pulley has a groove separating two flanges. The groove is what the rope bears on. On a Gray-B-Gon, the groove is a 1" length of PVC pipe with a nonskid surface, and the flanges are plastic container bottoms.
Clean the surface of the PVC pipe length with a paper towel and alcohol, and let it dry on a clean, flat surface. Measure and cut a 5-1/4" length of anti-slip tape. Peel about 1" of the backing and fold it back. Avoid letting the adhesive touch anything.
Place the tape on edge beside the 1" pipe. Success now depends on avoiding accidental contact with the adhesive, and on keeping the tape edge in light contact with the flat surface, for alignment.
Press the folded backing against the pipe, then slide your finger toward the exposed tape end. Once the tape end sticks, pull the loose end of the backing to expose more adhesive. Press this exposed adhesive against the pipe, rotate and repeat. When it's fully mounted, you should see a gap of about 1/32".
You will find ideal flanges in your grocery store: tubs, with rounded walls, that once contained olives or other delicacies. Don't use tubs with straight walls that extend below the bottom, to form a strengthening ridge. The rounded wall defeats the drive belt's attempts to climb off the flange. Tubs made of "PETE" (polyethylene terephthalate) look flimsy but resist weathering and UV.
Cut each flange from the nearly-smooth bottom of a plastic bottle or jar, including about 5/8" of the container's sidewall. Where the bottom meets the sidewall there must be a gentle curve, not a sharp-angled joint. Peanut-butter jars and small round refrigerator food containers work well, but are sturdy and may be hard to cut. Thin, flimsy PETE plastic may work well -- it's easy to cut, the load it will be required to support is very light, and it resists UV. Look at tubs of olives or other delicacies. Bottles with irregular or deeply lobed bottoms won't work.
First cut a 1-3/8" hole in the center of the container floor with a fine-tooth hole saw. Then cut the walls down to 5/8". Don't worry if the hole isn't precisely centered.