Part 16-Building the Bones-The ridgepoles

Step 3


The sidewalks never did materialize, weeds took over the forms, &bedlam took over my life. I got a phone call that the final $2000 dollars for the project would not be forthcoming (i.e. more like forflushing). So we went with plan 'Z'. Now maybe I should have more optimism but few people can say they started but did not finish a greenhouse five times. With the last official funds for the project I bought the material for the ridgepoles. Ideally, these would be huge I-beams with all kinds of fancy brackets. Instead, I went with simple flat surfaces, a 2x6 aluminum beam with 1/4 inch walls was the first choice, but after some rebudgeting, I dropped it down to 2x4. The trick, if there is one, is to make sure that in a record snow load, the ribs break and not the beam (or so I keep telling myself).

The diabetes had really been beating me up and so three weeks before the beams came I signed up for carpal tunnel surgery, fingers in my left hand were numb. About a week after the surgery, here comes the truck from Art Iron (Arco Steel), same fellow that went off the driveway and lost the truck in the mud the spring before with over 75 tons of iron on board. Kept him out of our driveway (neighbor boys had filled in the damage he did the time before) and this time I remembered to wear gloves so that he wouldn't bloody me moving his clamps like the time before. And as I'm standing there I think to myself, he's not stupid enough to try to roll a 200 lb beam that I'm holding onto, uugh. Tough telling the surgeon how my thumb, the source of previous concern, was now a black and blue wonder.

When the aluminum arrived there were also supports for the ridgepoles, two C-channel pieces that would hold most of the weight. I was able to make brackets from that stock by cutting on an angle with my handy (actually not so handy) Craftsman miter saw. You see part of the holdup, roughly 3 weeks was searching for a way to fix the saw. As I went to chop the first upright the, electrical box and switch came off in my hand. Since more than a year had passed, they refused to fix it. It was clearly a lemon design and I have yet to figure out how to hold them accountable. But I finally succumbed to wrapping the entire assembly with a very large adjustible hose band. Works but I am constantly worried that some huge catastrophe will ensue involving loose electrons and carbide teethy things, indeed, "arm"ageddon! I may need to add some duck tape to that fix. The laser cut guide has been a real weapon and serves two purposes, so never turn it off. You see the unexpected benefit is safety, if that laser is on, the monster is armed! And I'm one of those guys, I'm thinking about adjusting to 26.5 degrees and moving it to the work piece, not, gee the switch is on the carrying handle and I could really catch my %^&* on this thing.

The pictures below illustrate the C-channel supports, the rope trick using stainless steel eyebolts to redirect the force, and the brush that has grown up as a result of hiding indoors all summer. One of the compelling reasons for pulling the plug during the month of August is that every year I have gotten into some toxin during that month that has landed me in the hospital 3 out of the last 4 years. Last year, I almost lost both arms and the hormone treatments needed to knock it down were undoubtedly the source of my current diabetes. So why tempt fate? Aluminum and stainless steel are pretty durable even if people are not! So far no sign of the Boogeyman, but we are keeping our eyes peeled.

 

The Plan-Or, how did they build the pyramids??

I used an old Indian snare secret as a force amplifier to raise the 200 lb ridgepole with a 5 lb bucket of paint. Worked beautifully, I can now raise a 50 ton pyramid block or an Easter Island statue by myself and without breaking a sweat and without a pulley, cool!!

The physics are interesting and the rough calculations look like those in a hydraulics book for burst pressure. Each time you wrap the top pole one turn you create a huge amount of friction (actually stiction). This allows a small mass to hold a very large mass in check. In a snare, you create a two stage amplifier, in the first stage you wrap string or twine around a branch, with the bait and release on one end. The other end goes to a rope, wrapped around a branch, the second stage, that holds a huge rock or bent sapling in check attached to a noose. The animal takes the bait, the string unwraps, that releases the second loop to the rock which then activates the noose. You can easily cut a small animal in half, and as a former assistant Boy Scout leader, I made the mistake of showing this to the scouts. The lesson came to a sudden end when one of the boys accidentally triggered his own trap but not before several unfortunate critter deaths!

Each time I levered the support beam for my greenhouse upward, the rope relaxed allowing the bucket to drop. After several minutes the beam was 10' up and the bucket was on the ground... Did I forget to mention that stored energy has a tendency to get loose, in this case about 2000 foot-pounds, hence my concern, a shotgun shell is about 60 foot-pounds as I remember. Good news, job is done! Understand this can become an odd sort of deadly trebuchet if you slip. Here is a program in Visual Basic to calculate the required counterweight (cw.zip).

Well, you don't want to stand under the object, and work still equals force times distance. But yep, you can raise the dead with a 5 lb bucket! And I can reduce the power needed (energy per unit time-E/t) to near zero. This is especially important if you have a labrador retriever and are diabetic :-) 

Actual Data: Proving that I love to exaggerate and am afraid of dying (who knew?):

Beam Weights Counterweight #Wraps
Beam #1 Weight 65.5 lbs /2 22.8 lbs 2
Beam #2 Weight 43.42 lbs/2 9.8 lbs 2


The first glazing appears. Can we get it caulked before winter sets in ???

Part15.html
This page created by Edward A. Kimble
Last modified 09/18/2010