Made In The Shade

[jojo]

Anyone ever made one of these? I'm interested in making one for my own house.



What kind of math do you use to get the hollow on the sides...or would you just eyeball it?

Also, what would you buy to use as a post?

Thanks guys!

[gene]

I considered putting one in my backyard last year. Didn't do it.

sailrite.com has a video on how to make them. They also sell the hardware.


gene

[byhammerandhand]

Hyperbolic paraboloid.     AKA  "Pringles"

z/c = y^2 / b^2  -  x^2 / a^2
   

But all you really need is four anchor points at different levels -- two lower and two higher on opposite diagonals.





Keith  
B.S. Math
M.S. Math

[jojo]

Wow Keith; that's more thinking than I've done in years. I get that it's mounted that way, but there are also curves on the sides, aren't there?
Also, could I use a post that you'd use for chain link fencing?

[byhammerandhand]

Just draw a gentle curve for the edge hems.   The woodworker's way to do this is to get a thin piece of material (metal, wood, plastic, etc.), pin the ends to the corners, pull the center to get the shape you want (or run a cord between the ends) and trace out the curve.
This, http://www.leevalley.com/US/wood/page.aspx?p=44631&cat=1,42936,50298 , on a larger scale.

Sailrite's video (below, recommends a 4-6% "hollow" (depth of the arc / chord length)


Being 6'5"  (195 cm), I'd want it high enough that I didn't have to duck to get out from under it.

Gene's reference: http://www.sailrite.com/Building-Structural-Awning-Online-Streaming-Video

[Mojo]

JoJo:

Please excuse me for hijacking your thread for a second but really...........who the hell in their right mind goes and spends 5 years getting a degree in math ? Are these people nuts ? I hated math in school and did just enough to get by and graduate the 6th grade along with Jethro Bodine .

Then you have people like Keith and my wife that get masters degrees in this crap. My wife got a BS at the University of Sydney, Australia with dual majors in analytical chemistry and applied math and then went on and got a masters in math education.

This should have been my first warning. I married the geek anyways. :) She now chairs the math department at a private catholic high school and teaches the upper level maths ( Calculus/Calculus AP ). And she kloves it. She gets all giddy like a little kid over math.

If you think algebra is wacked you should see the " Theory " maths that her and Keith had to take. It is what I call the long hair math. None of it makes sense.

I cannot speak for Keith but can easily say my wife, while grounded and a loving person, is, shall we say,  different. Most math majors are. They see the world in numbers which makes them weird.............lol....... Don't get me wrong, I do love my wife. She makes things interesting at home. :)

OK, back to the topic. Just had to bust Keith's chops. I never let a moment go by without harassing a math major. They deserve it. :)

Chris

[byhammerandhand]

Calculus was what got me interested but abstract algebra was what I really liked.   Number theory, linear algebra, group theory, Galois theory, etc.   I was having a discussion last week with my 8 year old grandsons regarding number bases (they brought it up) so we discussed base 2, base 8, base 12, and base 16 number systems.  Their mom has a masters in industrial engineering with emphasis in stats, and papa has a bachelor's in physics with a PhD in mechanical engineering (rocket science).   They don't stand a chance with both parents and 3 of 4 grandparents in STEM.

[Mojo]

Good gawd. That is alot of education. I always wanted to be a surgeon and had the brains but no the drive. Maybe if I didn't major in cheerleaders, gym and lunch I would have made it to med school. :)

Chris

[JuneC]

But fractal geometry is so much fun!  Hated algebra and its variants, aced trig.  Calculus was fun but challenging.  Theoretical stuff is just too.... theoretical.  I'm visual. 

Anyhoo, Jojo, those are a knit fabric.  The arc is caused by the elastic effect.  Frankly, I'd never put anything knit/elastic outdoors because in a year it would be finished.  Costco has them for a very good price.  Trivantage sells the knit shade fabric.  But I don't ever make anything for myself that I can buy good quality for way less - for instance, my bbq grill cover came from Home Depot.  I could replace it 3 times over versus making from scratch. 

June

[Mike]

   Number theory, linear algebra, group theory,.................. Galois theory we discussed base 2, base 8, base 12, and base 16 number systems.  ..

you all are talking way over my head  I like to eye ball it ;
but I was a band major

[baileyuph]

So, the thinking is those arcs along the edge of the shade (the canopy or whatever) are a result of the tensions on it?

I was thinking that it was cut that way, of course It never crossed my mind that the shade is actually a screen shade either, much less stretches.

Whatever, it has a neat look.  I envisioned plane geometry; radius of the circle passing though the ground position of two poles on each side, then a straight line connecing the poles representing the cord of that arc circle.  then the perpendicular bisector of the cord represents where the circle arc radius passes from circle center point, through the center of the cord, and then the center of the arc (BTW, that determines the arc height).  If the shade is a rectangle,but not square, all this computed twice, once for opposite sides will give an arc height with symmetry like the requestor wants.  It can be laid out on the ground, very visual.

Oh well, all that and about $1.50 with a coupon, or senior discount will get you a cup of coffee at McDonalds.  LOL.  But, the material stretches to an arc symmetricaly on all sides.  I didn't learn that in college.  LOL.

Now, I know the short answer if a customer like that comes along.

Doyle

[byhammerandhand]

Stretching the "hollows" was my first thought, assuming the fabric has two-way stretch?    From the Sailrite video, they cut them.

Of course, there's June's point: http://www.leevalley.com/US/garden/page.aspx?cat=2,42194&p=70744

Senior McCoffee is 99 cents around here.   I made the mistake of getting the grandkids a soft drink at McDonald's on a trip last week.   They gave me large cups because they're all $1 this summer.   They wanted root beer, but ended up with Cokes.    12 hours later, they were still hyped up on caffeine.

So, the thinking is those arcs along the edge of the shade (the canopy or whatever) are a result of the tensions on it?

Oh well, all that and about $1.50 with a coupon, or senior discount will get you a cup of coffee at McDonalds.  LOL.  But, the material stretches to an arc symmetricaly on all sides.  I didn't learn that in college.  LOL.

Now, I know the short answer if a customer like that comes along.

Doyle

My middle daughter got turned off to math in Jr. High.   Before I realized what a lousy teacher she had it was a couple months in, then we spent time every evening trying to teach what the teacher couldn't.   New book that the teacher didn't understand and going through a divorce.    For a project my daughter had to do, we got a program on mapping fractals.  We printed the Mandelbrot fractal on page size.    Then zoomed in so the major diameter was the size of Saturn's orbit and printed off the page-sized view, that looked pretty much the same.    The teacher was dumbfounded.  She'd never heard of fractals.

[Mojo]

It is very hard finding qualified math teachers. Most do not have math backgrounds and my wife has seen history teachers pulled in to teach basic level math because of the shortage of these teachers. It is a rarity for someone like my wife who has a masters in math education to teach high school. Most have taken their degree and put it to use in the private sector working for a scientific type company. Many have gone on to be accountants.

Good chemistry and math teachers are hard to find. Highly degreed people in these subject areas fled the coop and are hiding out in the private sector making twice what they would as a teacher with alot less headaches.

Chris

[byhammerandhand]

That would be my wife.   When she tried to go back to secondary school after getting our kids into school while being adjunct at a couple of local universities, she said it had changed too much.   Got her CPA.

Doesn't really excuse people who are inept or apathetic in their jobs.   Youngest daughter sees this every day as a school psychologist.  I have a friend who retired as a master teacher in local public schools.  Her comment was if you keep yourself out of trouble, you are pretty much left alone, regardless of how well you perform your job.

I have a niece who's an elementary school teacher and she's always whining that she has to go back to work after holidays and summer.   She apparently does not realize most people have to work more than 180 days a year.

It is very hard finding qualified math teachers. ... Many have gone on to be accountants.

Good chemistry and math teachers are hard to find. Highly degreed people in these subject areas fled the coop and are hiding out in the private sector making twice what they would as a teacher with alot less headaches.

Chris

[gene]

A man walks into a bar and orders 10 times more drinks than everyone else.
The bartender says, "Now that's an order of magnitude!"

Why is six afraid of seven? Because Seven Eight (ATE) Nine.

How do you make 7 even? Remove the "S".

What did the number zero say to the number eight? "Nice belt."

Did you hear about the constipated mathematician? He worked it out with a pencil.

:)