Parts for Ground Board:
Plywood: For the ground board and chair base, I bought a 4 foot by 8 foot - 23/32" exterior grade plywood from Lowes. It is large enough for the two pieces needed. An option is to have the hardware store cut both pieces for you.
1. For the groundboard cut a 40" by 40" piece of plywood and draw lines from corner to corner to locate center:
2. For the large sprocket, I used the gear assembly from my son's discarded bike. You can buy sprockets online or for a better deal, stop by your local bike shop. They should have many old sprockets they can sell you for a buck or two.
3. Fasten the large sprocket to the "Seat Mount For Boat Pedestal" with 2 inch 1/4-20 screws, washers and nuts. I later added two more screws for a more secure mount (see first photo in step 4)
4. Attach the "Seat Mount For Boat Pedestal" with gear to the center of the plywood for ground board with four 1/4-20 by 1.5 inch screws, washers and nuts:
5. Cut 4 - three inch long pieces from the 2x4 for the groundboard legs and attach with 9X2 wood screws to all four corners:
6. Cut foam board with a utility knife 30 inches in diameter with a square hole in center for the "Seat Mount For Pedestal Base". The foam board will act as a spacer to help support the bike chain and keep it from drooping since the chain will be mounted horizontally.
7. Fasten the small sprocket onto the drill arbor using nuts and tighten in place. I ground flat sides on the round shaft of the arbor for a more secure fit in the drill chuck to avoid slipping. Some arbors already come with flat sided shafts. I bought the used small sprocket unit below from my local bike shop for $1. There are actually two sprockets screwed together that I had difficulty separating, so I just left them together and use the chain on the smaller sprocket.
8. Tack or staple the foam board from step 6 onto the ground board. Here is a photo of the completed ground board with bike chain and small sprocket:
The Groundboard is complete!
Next Page - Component No. 2 - Construction of Chair Base
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