GGs,
Scott's mention of jacks and cranes and blocking earlier today
reminded me of one of last summer's projects. It involves old tools
and wood, but not of a sort we traditionally discuss in this forum.
My house is built on telephone poles driven into the ground about ten
feet from Goldstream Creek, which is a meandering creek just north and
west of Fairbanks. Normally, the water is between eight and twelve
feet below the banks, and it's about 40 feet from one bank to the
other. We have a nice bridge across it, made from a pair of spruce
logs laid across the Creek, with 2x6 planks nailed between the log
supports.
In June it rained. A lot. Since most of the ground around here is
permanently frozen year round, it doesn't take much to saturate the
active layer at the surface with water. July started off with a
couple more inches of rain, and the Creek went over it's banks. About
two feet over:
http://youtu.be/PCjNAKWWBT4
Taking our bridge with it:
http://youtu.be/_-kH3M7d0PY
After the water came back down, the bridge was grounded around a
couple bends, conveniently behind our back cabin. Here it is after I
removed more than half of the planking:
http://media.swingleydev.com/img/photolog/2014/07/disassembling_old_bri
dge_2014-07.jpg">http://media.swingleydev.com/img/photolog/2014/07/disassembling
_old_bridge_2014-07.jpg
The guy that came out to help us lift up our log cabin to prevent
future flooding damage mentioned that I should just lift the logs back
up where they were, put new planks on it, and I'd have my bridge back.
I've moved some heavy things (every push a Harley a mile down I-5
after running out of gas?), but nothing quite as heavy as a pair of 50
foot spruce logs, and certainly not in a situation like the banks of a
creek.
But it turned out not to be all that difficult. I built an A-frame
from a pair of 8 foot 4x4 posts and a carriage bolt, got a pair of
rope winches and a strong pulley. With the A-frame extended out over
the bank and the rope from one winch tied to the end of the log, run
through the pulley at the top of the A-frame, then through the winch
anchored to a tree, and the rope from the other winch tied to the top
of the A-frame to control it's angle over the Creek, I was able to
winch the end of the log up to the level of the bank, then up an onto
the bank.
The trick is to keep the A-frame at an angle over the Creek, *and* the
rope tied to the log out even farther, such that the "log -- A-frame
-- anchor tree" angle was always greater than 90 degrees. If it's
greater than 90 degrees, tightening the winch raises the end of the
log, and pulls down on the A-frame. When the angle gets closer to 90,
tightening the winch causes both the end of the log and the top of the
A-frame to rise, and eventually the A-frame comes flying back at the
winch, dropping the log back where it came from. It took me a few
tries before I figured out the physics of how this works...
Here's a shot of the first lift:
http://media.swingleydev.com/img/photolog/2014/08/end_of_the_log_raised
_to_the_bank_2014-08.jpg">http://media.swingleydev.com/img/photolog/2014/08/end_
of_the_log_raised_to_the_bank_2014-08.jpg
and the second:
http://media.swingleydev.com/img/photolog/2014/08/south_side_end_raisin
g_2014-08.jpg">http://media.swingleydev.com/img/photolog/2014/08/south_side_end_
raising_2014-08.jpg
and the last lift from below (in a canoe):
http://media.swingleydev.com/img/photolog/2014/08/almost_there_2014-08.
jpg">http://media.swingleydev.com/img/photolog/2014/08/almost_there_2014-08.jpg<
/a>
After a couple weekends of work, and nailing down a bunch of rough cut
2x6 planks, the bridge was completely restored in it's new location:
http://media.swingleydev.com/img/photolog/2014/08/decking_is_almost_com
plete_2014-08.jpg">http://media.swingleydev.com/img/photolog/2014/08/decking_is_
almost_complete_2014-08.jpg
Every time I go back there, I'm amazed that I was able to do all that,
by myself, with nothing but a couple winches, a pulley, some ropes and
a simple A-frame. Physics is pretty cool.
One advantage of using a rope winch is that it has a built-in safety:
if you're putting more weight on the winch than it's designed for, the
rope just slips. With a come-a-long, reaching the limits is liable to
suddenly break something, which is a lot more dangerous.
One aside: the guy that came to help us raise our back cabin used a
pair of "railroad jacks", one on each end of the bottom logs of the
cabin. If you ever see a pair of these gadgets at an auction or a
yard sale or something, they're amazing. Here's what one looks like,
lifting the corner of our cabin:
http://media.swingleydev.com/img/photolog/2014/08/raising_the_back_cabi
n_2014-08.jpg">http://media.swingleydev.com/img/photolog/2014/08/raising_the_bac
k_cabin_2014-08.jpg
Cheers,
Chris
--
Christopher Swingley
Fairbanks, Alaska
http://swingleydev.com/
cswingle@s...
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