Tuesday, July 31, 2012

Jib, my new best friend.

The older I get the weaker I get. I just cant lift what I could back in my twenties. I remember dragging some pretty hefty steel out of the rack when I made my living as a fabricator. You really didn't give it much thought. It was just part of what you did. Now days I use any mechanical advantage I can apply. With a pretty creaky back and anticipating it just getting harder to lift some things I hatched a plan more out of sheer necessity.
I started researching wall and column mounted jib cranes. There is a example of a free standing one down the street from the shop that got me stoked about building my own (while I still can). Designing your own crane is not something you take lightly. It needs to be well thought out with correctly sized materials and some real engineering. After doing my engineering homework I took field dimensions in the shop and got busy with the mechanical design as well as gathering the needed materials.
 A few weeks later these are the pivots and their mounts.I didn't want to alter the building or compromise the concrete column holding up the ceiling by drilling huge anchor holes in it. The design called for sandwiching the column between two large steel channels. These were carefully preloaded with high strength studs to provide the needed clamping load for the crane design load and safety factors.
Unfortunately I had to splice the main beam. I wanted a larger radius of coverage than the beam I got could do, so I had to add a few feet onto it. I fretted over this for a while trying to decide which end should have the splice and what the spice would be reinforced with.

I was able to score a really nice chain fall and trolley off Craigslist. I had to drive all the way down to San Jose to get it from an Industrial liquidator down there. It turned out to be perfect for my project. I had been looking for a chain fall and a trolley separately and here was the whole package ready to slip onto my beam.

Now for the hard part. Getting the thing put up safely all by myself. Its about 400 lbs as it sits in this picture.
The start was a little awkward. Carrying heavy steel bits up and down a tall ladder sixteen feet up in the ceiling was not working very well. I needed something different.

To be continued......

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