The 21st Century learning experiences gained as the community, school and businesses design, plan and build a 32 foot long Town Lattice Truss covered bridge for the Village of South Wayne, Wisconsin.
Tuesday, September 5, 2017
Let the challenges continue
For sure the first logs to go on above the windows are the most challenging!
First there is the challenge of getting the 24 foot solid oak log to the top of the wall. Ramps were out of the question because when the ramp gets over your head you have no leverage to push and at 400 to 500 pounds there is a lot of friction between the log and the ramp. This would require a winch. I recycled one of my 2000 pound capacity 20:1 worm drive winches from a past covered bridge project. Mounting a 16 foot 4x4 to my scaffolding on wheels would do the trick. I could move the set up around to the different walls and safely lift them from the inside.
With the winch mounted and a snatch block above I would build a holder for the Milwaukee Hole Hawg drill that would drive it.
This went very well. Two boards were used. They would hang on the scaffolding and form a sandwich that could be loosened.
This would allowed the drill to be slid back so that the hand crank could be used for fine adjustments and better control of the log when notching it.
Just one more thing was needed. A remote switch that would allow me to turn on and off the drill during the raising process to make this a one man operation. The remote was later changed to an in line hand held switch that was more reliable. So now I could rig up the log and control its raising to the top of the cabin wall. Pretty neat!
The laying out and cutting of the two logs over the door and windows was a challenge and required the better part of two days! But a good learning experience for sure.
The last step in the process was to drill 1.5" diameter holes for pegs that would be used to pin the lower wall segments to the top log and knit the walls together. Now this oak is hard as rock and trying to put pressure on the drill from the top of a 10 foot ladder is a problem.
My 175 pounds could not get the job done. I had a choice, go home eat and gain 75 pounds or rig up something to do the job. Well I had some disc weights around so I strapped them up. With one on each side of the cabin wall it worked pretty good. Yes the drill is sharp but the heel clearance is very slight and with this hard of material it takes a lot of downward force to get the bit to bite.
You have heard of the saying, "putting a square peg into a round hole". Well this is a good application of that. This is a temporary peg that will hold the logs. Having only four points of contact the peg can be sawed off and easily removed when the cabin is dissembled and taken down. For final assembly full 1.5" diameter round oak pegs will be used and they will LOCK the logs together tight! The geometry used to calculate the size of the square peg would make my old high school geometry teacher smile.