Sunday, September 25, 2011

Skipping around on projects

While looking for a source of replacement logs for the cabin restoration project I had some time on my hands. Not wanting to waste it I went back to work on Cabin Bridge #6. My original plan was to use railroad ties for abutments for this bridge. With the bridge design change in width from 8 to 10 feet the railroad ties would be to short. You can see them piled up at the top of the picture. The solution would be four 2 foot diameter piers. How hard could that be?

Well considering that the site is off the roadway and in the woods there were plenty of "learning opportunities".

Lets reflect on them in reverse. How will we get 3 cubic yards of concrete into the 2 foot diameter fiber form tubes? Where is that darn Easy Button when you need it!

 How will one person, working alone support, locate and level the correct length of form tube in each of the pier holes?  This was tricky but a close study of the picture shows my helpers, vertical Z axis board, pivoting X and Y 2x2 attached to form and batter board strings above. With the addition of two staked parallel side boards and some screws into the tube the deed was done!

How deep below grade would the piers need to be (4 foot) and how would they be dug? That was easy!

The end results were 4 - 24 inch diameter piers from 5' to 7' long centered to support my 32' long, 10' wide, 12,000 pound Town Lattice Cabin Bridge #6.

Puzzler - What is the formula for calculating the volume of these tubes? How many cubic feet in one cubic yard?

Tech Vocab - Fiber Form, Batter Boards, Plumb Bob, Transit, X, Y, Z axis

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